Integrated database and analysis system for the evaluation of freeway corridors for potential ramp signaling : [summary].

DOT National Transportation Integrated Search

2011-01-01

Ramp signaling is the installation of traffic signals on freeway on-ramps. Studies have shown that in many locations, ramp signaling helped alleviate traffic congestion and improve safety. However, not all freeway locations are suitable for ramp sign...

Cellular automata model for use with real freeway data

DOT National Transportation Integrated Search

2002-01-01

The exponential rate of increase in freeway traffic is expanding the need for accurate and : realistic methods to model and predict traffic flow. Traffic modeling and simulation facilitates an : examination of both microscopic and macroscopic views o...

Development of an Analysis Tool for Evaluation of Marginal Impacts of Freeway Incidents in the Las Vegas Area Using FAST’s Dashboard Freeway Data.

DOT National Transportation Integrated Search

2014-01-21

Incidents are a major source of non-recurring congestion on freeways. In addition to costing millions of dollars in the loss of life, injuries and property damage, traffic incidents also cause additional losses due to the resulting traffic congestion...

Mining vehicle classifications from the Columbus Metropolitan Freeway Management System.

DOT National Transportation Integrated Search

2015-01-01

Vehicle classification data are used in many transportation applications, including: pavement design, : environmental impact studies, traffic control, and traffic safety. Ohio has over 200 permanent count stations, : supplemented by many more short-t...

Neural network model for automatic traffic incident detection : executive summary.

DOT National Transportation Integrated Search

2001-04-01

Automatic freeway incident detection is an important component of advanced transportation management systems (ATMS) that provides information for emergency relief and traffic control and management purposes. In this research, a multi-paradigm intelli...

Estimation of traffic recovery time for different flow regimes on freeways.

DOT National Transportation Integrated Search

2008-06-01

This study attempts to estimate post-incident traffic recovery time along a freeway using Monte Carlo simulation techniques. It has been found that there is a linear relationship between post-incident traffic recovery time, and incident time and traf...

Macroscopic modeling of freeway traffic using an artificial neural network

DOT National Transportation Integrated Search

1997-01-01

Traffic flow on freeways is a complex process that often is described by a set of highly nonlinear, dynamic equations in the form of a macroscopic traffic flow model. However, some of the existing macroscopic models have been found to exhibit instabi...

Neural network model for automatic traffic incident detection : final report, August 2001.

DOT National Transportation Integrated Search

2001-08-01

Automatic freeway incident detection is an important component of advanced transportation management systems (ATMS) that provides information for emergency relief and traffic control and management purposes. In this research, a multi-paradigm intelli...

Mining vehicle classifications from the Columbus Metropolitan Freeway Management System : [summary].

DOT National Transportation Integrated Search

2015-01-01

Vehicle classification data are used in many transportation applications, including: pavement design, : environmental impact studies, traffic control, and traffic safety. Ohio has over 200 permanent count : stations, supplemented by many more short-t...

Low Cost Wireless Network Camera Sensors for Traffic Monitoring

DOT National Transportation Integrated Search

2012-07-01

Many freeways and arterials in major cities in Texas are presently equipped with video detection cameras to : collect data and help in traffic/incident management. In this study, carefully controlled experiments determined : the throughput and output...

Quantifying the impact of new freeway segments.

DOT National Transportation Integrated Search

2013-05-01

Many freeway users complain that new freeway segments immediately fill up with traffic after they are constructed. This : diminishes the advantages of reduced costs and reduced driving time that would make freeways theoretically superior to : arteria...

Traffic behavior at freeway bottlenecks.

DOT National Transportation Integrated Search

2014-09-01

This study examines traffic behavior in the vicinity of a freeway bottleneck, revisiting commonly held : assumptions and uncovering systematic biases that likely have distorted empirical studies of bottleneck : formation, capacity drop, and the funda...

Reevaluation of Ramp Design Speed Criteria

DOT National Transportation Integrated Search

1999-12-01

Current freeway entry ramp design speed criteria were evaluated through observations of twenty ramps in four Texas cities. Field observations of ramp and freeway traffic speed-distance relationships were made using videotaping methods. Traffic operat...

RHODES-ITMS-MILOS : ramp metering system test

DOT National Transportation Integrated Search

2002-04-01

The RHODES-Integrated Traffic Management System Program addresses the design and development of a real-time traffic adaptive control system for an integrated system of freeways and arterial roads. The goals of this project were to test coordinated, a...

Evaluating the benefits of dynamic message signs on Missouri's rural corridors.

DOT National Transportation Integrated Search

2011-12-01

Dynamic message signs (DMSs) are traffic control devices that provide real-time traveler information and are used for traffic warning, regulation, routing and management. DMSs on freeways in rural areas in southeast Missouri were evaluated. First, mo...

Connected vehicle enabled freeway merge management - field test.

DOT National Transportation Integrated Search

2016-01-01

Freeway congestion is a major problem of the transportation system, resulting in major economic : loss in terms of traffic delays and fuel costs. With connected vehicle (CV) technologies, more : proactive traffic management strategies are possible. T...

Quantifying incident-induced travel delays on freeways using traffic sensor data : phase II

DOT National Transportation Integrated Search

2010-12-01

Traffic incidents cause approximately 50 percent of freeway congestion in metropolitan areas, resulting in extra travel time and fuel cost. Quantifying incident-induced delay (IID) will help people better understand the real costs of incidents, maxim...

Modeling hurricane evacuation traffic : evaluation of freeway contraflow evacuation initiation and termination point configurations.

DOT National Transportation Integrated Search

2010-06-01

Over the last five years, the departments of transportation in 12 coastal states threatened by hurricanes have developed plans for the implementation of contraflow traffic operations on freeways during evacuations. Contraflow involves the use of one ...

Use of Intermodal Performance Measures by State Departments of Transportation

DOT National Transportation Integrated Search

1974-01-01

The traffic-density buildup following a lane blockage on a four-lane freeway carrying low-density traffic is determined for several different densities (0.0065, 0.0100, and 0.0106 vehicles per foot) characterizing the freeway. The time for the traffi...

Safe and effective speed reductions for freeway work zones phase 2.

DOT National Transportation Integrated Search

2014-09-01

Freeway preservation projects typically require construction workers to conduct their : work in close proximity to ongoing traffic and often reduce traffic flow to a single lane while work is : undertaken in an adjacent lane. Due to the short-term na...

Freeway travel time estimation using existing fixed traffic sensors : phase 2.

DOT National Transportation Integrated Search

2015-03-01

Travel time, one of the most important freeway performance metrics, can be easily estimated using the : data collected from fixed traffic sensors, avoiding the need to install additional travel time data collectors. : This project is aimed at fully u...

Freeway travel time estimation using existing fixed traffic sensors : phase 1.

DOT National Transportation Integrated Search

2013-08-01

Freeway travel time is one of the most useful pieces of information for road users and an : important measure of effectiveness (MOE) for traffic engineers and policy makers. In the Greater : St. Louis area, Gateway Guide, the St. Louis Transportation...

Modeling hurricane evacuation traffic : evaluation of freeway contraflow evacuation initiation and termination point configurations.

DOT National Transportation Integrated Search

2006-06-01

Over the last 5 years, the Departments of Transportation in 12 coastal states threatened by hurricanes have developed plans for the implementation of contraflow traffic operations on freeways during evacuations. Contraflow involves the use of one or ...

Making the Traffic Operations Case for Congestion Pricing: Operational Impacts of Congestion Pricing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chin, Shih-Miao; Hu, Patricia S; Davidson, Diane

2011-02-01

Congestion begins when an excess of vehicles on a segment of roadway at a given time, resulting in speeds that are significantly slower than normal or 'free flow' speeds. Congestion often means stop-and-go traffic. The transition occurs when vehicle density (the number of vehicles per mile in a lane) exceeds a critical level. Once traffic enters a state of congestion, recovery or time to return to a free-flow state is lengthy; and during the recovery process, delay continues to accumulate. The breakdown in speed and flow greatly impedes the efficient operation of the freeway system, resulting in economic, mobility, environmentalmore » and safety problems. Freeways are designed to function as access-controlled highways characterized by uninterrupted traffic flow so references to freeway performance relate primarily to the quality of traffic flow or traffic conditions as experienced by users of the freeway. The maximum flow or capacity of a freeway segment is reached while traffic is moving freely. As a result, freeways are most productive when they carry capacity flows at 60 mph, whereas lower speeds impose freeway delay, resulting in bottlenecks. Bottlenecks may be caused by physical disruptions, such as a reduced number of lanes, a change in grade, or an on-ramp with a short merge lane. This type of bottleneck occurs on a predictable or 'recurrent' basis at the same time of day and same day of week. Recurrent congestion totals 45% of congestion and is primarily from bottlenecks (40%) as well as inadequate signal timing (5%). Nonrecurring bottlenecks result from crashes, work zone disruptions, adverse weather conditions, and special events that create surges in demand and that account for over 55% of experienced congestion. Figure 1.1 shows that nonrecurring congestion is composed of traffic incidents (25%), severe weather (15%), work zones, (10%), and special events (5%). Between 1995 and 2005, the average percentage change in increased peak traveler delay, based on hours spent in traffic in a year, grew by 22% as the national average of hours spent in delay grew from 36 hours to 44 hours. Peak delay per traveler grew one-third in medium-size urban areas over the 10 year period. The traffic engineering community has developed an arsenal of integrated tools to mitigate the impacts of congestion on freeway throughput and performance, including pricing of capacity to manage demand for travel. Congestion pricing is a strategy which dynamically matches demand with available capacity. A congestion price is a user fee equal to the added cost imposed on other travelers as a result of the last traveler's entry into the highway network. The concept is based on the idea that motorists should pay for the additional congestion they create when entering a congested road. The concept calls for fees to vary according to the level of congestion with the price mechanism applied to make travelers more fully aware of the congestion externality they impose on other travelers and the system itself. The operational rationales for the institution of pricing strategies are to improve the efficiency of operations in a corridor and/or to better manage congestion. To this end, the objectives of this project were to: (1) Better understand and quantify the impacts of congestion pricing strategies on traffic operations through the study of actual projects, and (2) Better understand and quantify the impacts of congestion pricing strategies on traffic operations through the use of modeling and other analytical methods. Specifically, the project was to identify credible analytical procedures that FHWA can use to quantify the impacts of various congestion pricing strategies on traffic flow (throughput) and congestion.« less

Characteristics of transitions in freeway traffic : final report, OTREC-RR-10-12 September 2010.

DOT National Transportation Integrated Search

2010-09-01

This research seeks to understand the characteristics of transitions as freeway traffic changes from one state to another. This study addresses the features of two types of transitions; transitions near a merge and transitions along shock waves durin...

Simulation-Based Testbed Development for Analyzing Toll Impacts on Freeway Travel

DOT National Transportation Integrated Search

2012-06-01

Traffic congestion has been a world-wide problem in metropolitan areas all over the world. Toll-based traffic management is one of the most applicable solutions against freeway congestion. This research chooses two toll roads, the SR-167 HOT Lane and...

Effect of flaggers and spotters in directing work zone traffic for Illinois expressways and freeways.

DOT National Transportation Integrated Search

2014-01-01

This research project focused on assessing the effectiveness and essential role of flaggers and spotters in : directing traffic for expressway and freeway work zones in Illinois with a posted speed limit greater than 40 mph. : The objectives of this ...

Development of a prototype vehicle-infrastructure integration system for real-time traffic management.

DOT National Transportation Integrated Search

2008-08-01

Freeway congestion is a major problem in many urban areas. It has been estimated that freeway incidents (events that impede the flow of traffic: accidents, disabled vehicles, etc.) account for one-half to three-fourths of the total congestion on metr...

Proactive assessment of accident risk to improve safety on a system of freeways : [research brief].

DOT National Transportation Integrated Search

2012-05-01

As traffic safety on freeways continues to be a growing concern, much progress has been made in shifting from reactive (incident detection) to proactive (real-time crash risk assessment) traffic strategies. Reliable models that can take in real-time ...

Heavy vehicle performance during recovery from forced-flow urban freeway conditions due to incidents, work zones and recurring congestion.

DOT National Transportation Integrated Search

2013-12-01

Information contained in the Highway Capacity Manual on the influence heavy vehicles have on freeway traffic : operations has been based on few field data collection efforts and relied mostly on traffic simulation efforts. In the : 2010 Manual heavy ...

Assessing segment- and corridor-based travel-time reliability on urban freeways : final report.

DOT National Transportation Integrated Search

2016-09-01

Travel time and its reliability are intuitive performance measures for freeway traffic operations. The objective of this project was to quantify segment-based and corridor-based travel time reliability measures on urban freeways. To achieve this obje...

Lane Blockage Effects on Freeway Traffic Flow

DOT National Transportation Integrated Search

1996-09-01

Intelligent Transportation Systems (ITS) apply advanced and emerging technologies in such fields as information processing, communications, control, and electronics to surface transportation needs. ITS encompasses a number of diverse program areas in...

New framework and decision support tool to warrant detour operations during freeway corridor incident management.

DOT National Transportation Integrated Search

2013-05-01

Up to 60% of freeway delays are due to non-recurrent congestion caused by reduced capacity on a freeway section coupled with long incident : durations. In such conditions, if proper detour strategies could be implemented in time, traffic could circum...

Design of lane merges at rural freeway construction work zones.

DOT National Transportation Integrated Search

2012-10-01

Practices for the design and control of work zone traffic control configurations have evolved over time : to reflect safer and more efficient management practices. However, they are also recognized as areas : of frequent vehicle conflicts that can ca...

Applying systems engineering principles to the development of transportation communication standards.

DOT National Transportation Integrated Search

2011-04-22

Using traffic control devices and communications equipment to monitor and control arterials and freeways has brought with it new challenges and a demand for new skills to the transportation industry. Some of the challenges include integrating informa...

Evaluating the effectiveness of active vehicle safety systems.

PubMed

Jeong, Eunbi; Oh, Cheol

2017-03-01

Advanced vehicle safety systems have been widely introduced in transportation systems and are expected to enhance traffic safety. However, these technologies mainly focus on assisting individual vehicles that are equipped with them, and less effort has been made to identify the effect of vehicular technologies on the traffic stream. This study proposed a methodology to assess the effectiveness of active vehicle safety systems (AVSSs), which represent a promising technology to prevent traffic crashes and mitigate injury severity. The proposed AVSS consists of longitudinal and lateral vehicle control systems, which corresponds to the Level 2 vehicle automation presented by the National Highway Safety Administration (NHTSA). The effectiveness evaluation for the proposed technology was conducted in terms of crash potential reduction and congestion mitigation. A microscopic traffic simulator, VISSIM, was used to simulate freeway traffic stream and collect vehicle-maneuvering data. In addition, an external application program interface, VISSIM's COM-interface, was used to implement the AVSS. A surrogate safety assessment model (SSAM) was used to derive indirect safety measures to evaluate the effectiveness of the AVSS. A 16.7-km freeway stretch between the Nakdong and Seonsan interchanges on Korean freeway 45 was selected for the simulation experiments to evaluate the effectiveness of AVSS. A total of five simulation runs for each evaluation scenario were conducted. For the non-incident conditions, the rear-end and lane-change conflicts were reduced by 78.8% and 17.3%, respectively, under the level of service (LOS) D traffic conditions. In addition, the average delay was reduced by 55.5%. However, the system's effectiveness was weakened in the LOS A-C categories. Under incident traffic conditions, the number of rear-end conflicts was reduced by approximately 9.7%. Vehicle delays were reduced by approximately 43.9% with 100% of market penetration rate (MPR). These results imply that from the perspective of traffic operations and control to address the safety and congestion issues of a traffic stream, smarter management strategies that consider both traffic conditions and MPR are required to fully exploit the effectiveness of the AVSS in the field. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modeling and Density Estimation of an Urban Freeway Network Based on Dynamic Graph Hybrid Automata

PubMed Central

Chen, Yangzhou; Guo, Yuqi; Wang, Ying

2017-01-01

In this paper, in order to describe complex network systems, we firstly propose a general modeling framework by combining a dynamic graph with hybrid automata and thus name it Dynamic Graph Hybrid Automata (DGHA). Then we apply this framework to model traffic flow over an urban freeway network by embedding the Cell Transmission Model (CTM) into the DGHA. With a modeling procedure, we adopt a dual digraph of road network structure to describe the road topology, use linear hybrid automata to describe multi-modes of dynamic densities in road segments and transform the nonlinear expressions of the transmitted traffic flow between two road segments into piecewise linear functions in terms of multi-mode switchings. This modeling procedure is modularized and rule-based, and thus is easily-extensible with the help of a combination algorithm for the dynamics of traffic flow. It can describe the dynamics of traffic flow over an urban freeway network with arbitrary topology structures and sizes. Next we analyze mode types and number in the model of the whole freeway network, and deduce a Piecewise Affine Linear System (PWALS) model. Furthermore, based on the PWALS model, a multi-mode switched state observer is designed to estimate the traffic densities of the freeway network, where a set of observer gain matrices are computed by using the Lyapunov function approach. As an example, we utilize the PWALS model and the corresponding switched state observer to traffic flow over Beijing third ring road. In order to clearly interpret the principle of the proposed method and avoid computational complexity, we adopt a simplified version of Beijing third ring road. Practical application for a large-scale road network will be implemented by decentralized modeling approach and distributed observer designing in the future research. PMID:28353664

Modeling and Density Estimation of an Urban Freeway Network Based on Dynamic Graph Hybrid Automata.

PubMed

Chen, Yangzhou; Guo, Yuqi; Wang, Ying

2017-03-29

In this paper, in order to describe complex network systems, we firstly propose a general modeling framework by combining a dynamic graph with hybrid automata and thus name it Dynamic Graph Hybrid Automata (DGHA). Then we apply this framework to model traffic flow over an urban freeway network by embedding the Cell Transmission Model (CTM) into the DGHA. With a modeling procedure, we adopt a dual digraph of road network structure to describe the road topology, use linear hybrid automata to describe multi-modes of dynamic densities in road segments and transform the nonlinear expressions of the transmitted traffic flow between two road segments into piecewise linear functions in terms of multi-mode switchings. This modeling procedure is modularized and rule-based, and thus is easily-extensible with the help of a combination algorithm for the dynamics of traffic flow. It can describe the dynamics of traffic flow over an urban freeway network with arbitrary topology structures and sizes. Next we analyze mode types and number in the model of the whole freeway network, and deduce a Piecewise Affine Linear System (PWALS) model. Furthermore, based on the PWALS model, a multi-mode switched state observer is designed to estimate the traffic densities of the freeway network, where a set of observer gain matrices are computed by using the Lyapunov function approach. As an example, we utilize the PWALS model and the corresponding switched state observer to traffic flow over Beijing third ring road. In order to clearly interpret the principle of the proposed method and avoid computational complexity, we adopt a simplified version of Beijing third ring road. Practical application for a large-scale road network will be implemented by decentralized modeling approach and distributed observer designing in the future research.

Traffic Monitor

NASA Technical Reports Server (NTRS)

1992-01-01

Mestech's X-15 "Eye in the Sky," a traffic monitoring system, incorporates NASA imaging and robotic vision technology. A camera or "sensor box" is mounted in a housing. The sensor detects vehicles approaching an intersection and sends the information to a computer, which controls the traffic light according to the traffic rate. Jet Propulsion Laboratory technical support packages aided in the company's development of the system. The X-15's "smart highway" can also be used to count vehicles on a highway and compute the number in each lane and their speeds, important information for freeway control engineers. Additional applications are in airport and railroad operations. The system is intended to replace loop-type traffic detectors.

Integrated CCTV.

DOT National Transportation Integrated Search

2004-01-01

The Virginia Department of Transportation (VDOT) has invested in extensive closed-circuit television (CCTV) systems to monitor freeways in urban areas. Generally, these devices are installed as part of freeway management systems (Smart Traffic Center...

Development of criteria and guidelines for installing, operating, and removing TxDOT ramp control signals.

DOT National Transportation Integrated Search

2009-05-01

The Texas Department of Transportation (TxDOT) uses ramp control signals (also called ramp meters or : flow signals) to control the rate at which vehicles enter the freeway. This helps TxDOT (1) promote a more : consistent and uniform flow of traffic...

Dynamic Stochastic Control of Freeway Corridor Systems : Summary and Project Overview

DOT National Transportation Integrated Search

1978-12-01

Systematic methodological approaches to overall traffic management from both short-term (real-time) and long-term (planning) perspectives have been developed. The approach embodies formulation and solution of interrelated mathematical problems from o...

Freeway ramp management in Pennsylvania.

DOT National Transportation Integrated Search

2011-03-31

This research identified the opportunities to implement ramp management strategies on freeways in Pennsylvania. The research : explored the need to integrate local arterial traffic signal systems with ramp management strategies to reduce the impacts ...

The nuisance due to the noise of automobile traffic: An investigation in the neighborhoods of freeways

NASA Technical Reports Server (NTRS)

Lamure, C.; Bacelon, M.

1980-01-01

An inquiry was held among 400 people living near freeways in an attempt to determine the characteristics of traffic noise nuisance. A nuisance index was compiled, based on the answers to a questionnaire. Nuisance expressed in these terms was then compared with the noise level measured on the most exposed side of each building. Correlation between the nuisance indexes and the average noise levels is quite good for dwellings with facades parallel to the freeway. At equal noise levels on the most exposed side, the nuisance given for these latter dwellings is lower than for others.

78 FR 68135 - Environmental Impact Statement: Los Angeles County, California

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-13

... part of 2014. FOR FURTHER INFORMATION CONTACT: Tami Podesta, California Department of Transportation... no access control. SR-138 Northwest Corridor Improvement Project proposes to improve the highway as a freeway, expressway with access control and/or traffic system/multi- modal facility. The SR-138 currently...

Phase III Autotrack : integrated CCTV.

DOT National Transportation Integrated Search

2005-01-01

The Virginia Department of Transportation (VDOT) has invested in extensive closed circuit television (CCTV) systems to monitor freeways in urban areas. Generally, these devices are installed as part of freeway management systems (Smart Traffic Center...

Evaluating the safety impact of adaptive cruise control in traffic oscillations on freeways.

PubMed

Li, Ye; Li, Zhibin; Wang, Hao; Wang, Wei; Xing, Lu

2017-07-01

Adaptive cruise control (ACC) has been considered one of the critical components of automated driving. ACC adjusts vehicle speeds automatically by measuring the status of the ego-vehicle and leading vehicle. Current commercial ACCs are designed to be comfortable and convenient driving systems. Little attention is paid to the safety impacts of ACC, especially in traffic oscillations when crash risks are the highest. The primary objective of this study was to evaluate the impacts of ACC parameter settings on rear-end collisions on freeways. First, the occurrence of a rear-end collision in a stop-and-go wave was analyzed. A car-following model in an integrated ACC was developed for a simulation analysis. The time-to-collision based factors were calculated as surrogate safety measures of the collision risk. We also evaluated different market penetration rates considering that the application of ACC will be a gradual process. The results showed that the safety impacts of ACC were largely affected by the parameters. Smaller time delays and larger time gaps improved safety performance, but inappropriate parameter settings increased the collision risks and caused traffic disturbances. A higher reduction of the collision risk was achieved as the ACC vehicle penetration rate increased, especially in the initial stage with penetration rates of less than 30%. This study also showed that in the initial stage, the combination of ACC and a variable speed limit achieved better safety improvements on congested freeways than each single technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

Validation of Variations in Mental Workload as a Function of Scenario Difficulty: Traffic Density and Visibility

NASA Technical Reports Server (NTRS)

2003-01-01

Fluctuations in mental workload can be expected as a function of traffic density and visibility. The aim of the current investigation was to establish simulation scenarios that differed in attentional processing requirements. Four scenarios were created and tested representing two levels of traffic density (urban versus freeway) and two levels of visibility (clear versus foggy). An array of mental workload assessment measures were used to exam changes in attentional processing requirements in each scenario. The assessment array consisted of physiological (P300 amplitude and latency) and behavioral (RT and accuracy) indices. Preliminary results indicate that workload differs significantly as a function of traffic density in rural versus freeway scenarios. Workload also differs significantly in rural versus freeway scenarios as a function of visibility as observed by a significant interaction between the two variables of interest. Results are discussed in terms of their application for validating the difficulty level of simulation scenarios as a format for examining mental workload.

Ramp meter design manual

DOT National Transportation Integrated Search

2000-01-01

Caltrans is committed to using ramp metering as an effective traffic management strategy to maintain an efficient freeway system and protect the investment made in constructing freeways by keeping them operating at or near capacity. Ramp Metering is ...

Freeway geometric design for active traffic management in Europe

DOT National Transportation Integrated Search

2011-03-01

Continued growth in travel on congested urban freeway corridors exceeds the ability of agencies to provide sufficient solutions and alternatives based on traditional roadway expansion and improvement projects. Several countries are implementing manag...

The role of traffic noise on the association between air pollution and children's lung function.

PubMed

Franklin, Meredith; Fruin, Scott

2017-08-01

Although it has been shown that traffic-related air pollution adversely affects children's lung function, few studies have examined the influence of traffic noise on this association, despite both sharing a common source. Estimates of noise exposure (L dn, dB), and freeway and non-freeway emission concentrations of oxides of nitrogen (NO x , ppb) were spatially assigned to children in Southern California who were tested for forced vital capacity (FVC, n=1345), forced expiratory volume in 1s, (FEV 1, n=1332), and asthma. The associations between traffic-related NO x and these outcomes, with and without adjustment for noise, were examined using mixed effects models. Adjustment for noise strengthened the association between NO x and reduced lung function. A 14.5mL (95% CI -40.0, 11.0mL) decrease in FVC per interquartile range (13.6 ppb) in freeway NO x was strengthened to a 34.6mL decrease after including a non-linear function of noise (95% CI -66.3, -2.78mL). Similarly, a 6.54mL decrease in FEV 1 (95% CI -28.3, 15.3mL) was strengthened to a 21.1mL decrease (95% CI -47.6, 5.51) per interquartile range in freeway NO x . Our results indicate that where possible, noise should be included in epidemiological studies of the association between traffic-related air pollution on lung function. Without taking noise into account, the detrimental effects of traffic-related pollution may be underestimated. Copyright © 2017 Elsevier Inc. All rights reserved.

Improving truck and speed data using paired video and single-loop sensors

DOT National Transportation Integrated Search

2006-12-01

Real-time speed and truck data are important inputs for modern freeway traffic control and : management systems. However, these data are not directly measurable by single-loop detectors. : Although dual-loop detectors provide speeds and classified ve...

Development of a statewide online system for traffic data quality control and sharing.

DOT National Transportation Integrated Search

2009-12-01

The Washington State Department of Transportation (WSDOT) operates thousands of Inductive Loop : Detectors (ILDs) on the freeways and highways of Washington State. The collection and disbursement of : this data is handled at the regional level, which...

Data mining of tree-based models to analyze freeway accident frequency.

PubMed

Chang, Li-Yen; Chen, Wen-Chieh

2005-01-01

Statistical models, such as Poisson or negative binomial regression models, have been employed to analyze vehicle accident frequency for many years. However, these models have their own model assumptions and pre-defined underlying relationship between dependent and independent variables. If these assumptions are violated, the model could lead to erroneous estimation of accident likelihood. Classification and Regression Tree (CART), one of the most widely applied data mining techniques, has been commonly employed in business administration, industry, and engineering. CART does not require any pre-defined underlying relationship between target (dependent) variable and predictors (independent variables) and has been shown to be a powerful tool, particularly for dealing with prediction and classification problems. This study collected the 2001-2002 accident data of National Freeway 1 in Taiwan. A CART model and a negative binomial regression model were developed to establish the empirical relationship between traffic accidents and highway geometric variables, traffic characteristics, and environmental factors. The CART findings indicated that the average daily traffic volume and precipitation variables were the key determinants for freeway accident frequencies. By comparing the prediction performance between the CART and the negative binomial regression models, this study demonstrates that CART is a good alternative method for analyzing freeway accident frequencies. By comparing the prediction performance between the CART and the negative binomial regression models, this study demonstrates that CART is a good alternative method for analyzing freeway accident frequencies.

Field Test of Slow Moving Traffic Alerting System on Freeways in Las Vegas, Nevada : Assessment of the Effectiveness of the Dynamic Message Signs on the Freeways in Las Vegas, Nevada.

DOT National Transportation Integrated Search

2015-10-17

It has been perceived that the travelers do not respond to the incident messages on the dynamic message signs in the Las Vegas area in Nevada. The objective of the study is to evaluate whether dynamic message signs (DMS) in the Las Vegas freeway syst...

Impact Of Rapid Incident Detection On Freeway Accident Fatalities

DOT National Transportation Integrated Search

1996-06-01

Heavily congested urban highways in the United States have spurred the development of Freeway Management Systems (FMS). Among the goals of these systems is the improvement of traffic management and the facilitation of more rapid incident detection an...

Forecasting the clearance time of freeway accidents

DOT National Transportation Integrated Search

2002-01-01

Freeway congestion is a major and costly problem in many U.S. metropolitan areas. From a traveler's perspective, congestion has costs in terms of longer travel times and lost productivity. From the traffic manager's perspective, congestion causes a f...

Freeway travel-time estimation and forecasting.

DOT National Transportation Integrated Search

2013-03-01

Real-time traffic information provided by GDOT has proven invaluable for commuters in the : Georgia freeway network. The increasing number of Variable Message Signs, addition of : services such as My-NaviGAtor, NaviGAtor-to-go etc. and the advancemen...

Real time freeway incident detection.

DOT National Transportation Integrated Search

2014-04-01

The US Department of Transportation (US-DOT) estimates that over half of all congestion : events are caused by highway incidents rather than by rush-hour traffic in big cities. Real-time : incident detection on freeways is an important part of any mo...

Evaluation of the effectiveness of ATM messages used during incidents : final report.

DOT National Transportation Integrated Search

2016-01-01

This project investigated the use of Intelligent Lane Control Signs based Active Traffic Management for : Incident Management on a heavily traveled urban freeway. The subject of the research was the ILCS : system on I-94 westbound in downtown Minneap...

Contribution of highway capital to industry and national productivity growth

DOT National Transportation Integrated Search

1973-10-01

The report contains the authors initial efforts aimed at extending the steady state freeway model for optimizing freeway traffic flow to a non-steady state model. The steady-state model does not allow reaction to continuously changing conditions whic...

Pueblo Freeway Management System (FMS) : final report

DOT National Transportation Integrated Search

2005-05-16

The Pueblo Freeway Management System (FMS) was a FY00 earmarked project. The objective of the project was to enable the Colorado State Patrol (CSP), the City of Pueblo Police Department (PPD), and CDOT (both Region 2 and Colorado Traffic Management C...

Highway traffic operations and freeway management : state-of-the-practice

DOT National Transportation Integrated Search

2003-03-01

This paper focuses on the proactive management of freeway facilities to balance the capacity of the transportation system and the prevailing demands and to respond to out-of-the-ordinary conditions (e.g., incidents, adverse weather, work zones, speci...

Criteria for implementing full-width/depth shoulders to accommodate hard shoulder running.

DOT National Transportation Integrated Search

2011-08-22

"WisDOT is considering constructing full-width/depth shoulders along certain freeway segments to carry traffic : during future freeway resurfacing or construction projects. The goal of this measure is to minimize lane closures and : congestion. WisDO...

Living near a Freeway is Associated with Lower Bone Mineral Density among Mexican Americans

PubMed Central

Chen, Zhanghua; Salam, Muhammad T.; Karim, Roksana; Toledo-Corral, Claudia M.; Watanabe, Richard M.; Xiang, Anny H.; Buchanan, Thomas A.; Habre, Rima; Bastain, Theresa M.; Lurmann, Fred; Taher, Maryam; Wilson, John P.; Trigo, Enrique; Gilliland, Frank D.

2015-01-01

Purpose Adults residing in rural areas have been linked with higher bone mineral density (BMD). We aimed to determine if this difference is due in part to air pollution by examining the relationships between traffic metrics and ambient air pollution with total body and pelvic BMD. Methods Mexican-American adults (n=1,175; mean 34 years; 72% female) who had participated in the BetaGene study of air pollution, obesity and insulin resistance were included in this analysis. Total body and pelvic BMD were estimated using dual-energy X-ray absorptiometry. Traffic and ambient air pollutant exposures were estimated at residences using location and ambient monitoring data. Variance component models were used to analyze the associations between residential distance to the nearest freeway and ambient air pollutants with BMD. Results Residential proximity to a freeway was associated with lower total body BMD (p-trend=0.01) and pelvic BMD (p-trend=0.03) after adjustment for age, sex, weight and height. The adjusted mean total body and pelvic BMD in participants living within 500m of a freeway were 0.02 g/cm2 and 0.03 g/cm2 lower than participants living greater than 1,500m from a freeway. These associations did not differ significantly by age, sex or obesity status. Results were similar after further adjustment for body fat and weekly physical activity minutes. Ambient air pollutants (NO2, O3 and PM2.5) were not significantly associated with BMD. Conclusions Traffic-related exposures in overweight and obese Mexican-Americans may adversely affect BMD. Our findings indicate that long-term exposures to traffic may contribute to the occurrence of osteoporosis and its consequences. PMID:25677718

Traffic detector handbook : third edition. Volume II

DOT National Transportation Integrated Search

2006-10-01

The objective of this Handbook is to provide a comprehensive resource for selecting, designing, installing, and maintaining traffic sensors for signalized intersections and freeways. It is intended for use by traffic engineers and technicians having ...

Enhancement of freeway incident traffic management and resulting benefits.

DOT National Transportation Integrated Search

2012-04-01

To improve traffic conditions on major highways plagued by non-recurrent congestion, most : highway agencies have invested their resources in two principal operational programs: incident response : and clearance, and traffic impact management. Howeve...

Traffic detector handbook : third edition. Volume I

DOT National Transportation Integrated Search

2006-10-01

The objective of this Handbook is to provide a comprehensive resource for selecting, designing, installing, and maintaining traffic sensors for signalized intersections and freeways. It is intended for use by traffic engineers and technicians having ...

Wrong-way vehicle detection : proof of concept.

DOT National Transportation Integrated Search

2013-03-01

Vehicles that enter freeway exit ramps going the wrong way present one of the most serious traffic hazards on : Arizonas urban freeways. Moler cites a study that finds on average 350 people are killed annually in the United : States as a result of...

User-friendly traffic incident management (TIM) program benefit-cost estimation tool, Version 1.2

DOT National Transportation Integrated Search

2016-01-01

Traffic incidents contribute significantly to the deterioration of the level of service of both freeways and arterials. Traffic Incident Management (TIM) programs have been introduced worldwide with the aim of mitigating the impact of traffic inciden...

Network origin-destination demand estimation using limited link traffic counts : strategic deployment of vehicle detectors through an integrated corridor management framework.

DOT National Transportation Integrated Search

2009-10-15

In typical road traffic corridors, freeway systems are generally well-equipped with traffic surveillance systems such as vehicle detector (VD) and/or closed circuit television (CCTV) systems in order to gather timely traffic information for traffic c...

Traffic prediction using wireless cellular networks : final report.

DOT National Transportation Integrated Search

2016-03-01

The major objective of this project is to obtain traffic information from existing wireless : infrastructure. : In this project freeway traffic is identified and modeled using data obtained from existing : wireless cellular networks. Most of the prev...

Assessment and validation of managed lanes weaving and access guidelines.

DOT National Transportation Integrated Search

2010-06-01

The goal of this project was to establish spacing requirements for access points to managed lanes : with respect to the location of entrance and exit ramps on the general purpose lanes of the freeway. Traffic : entering the freeway destined for the m...

Economic and quality of life impacts of route 21 freeway construction : final report, October 2009.

DOT National Transportation Integrated Search

2009-10-01

Opened to traffic in December 2000, the missing section of the Route 21 Freeway in Clifton : and Passaic (Hope Ave. to the Route 46 Interchange) was designed utilizing the equivalent to : the Context Sensitive Solutions (CSS) approach at ...

Incorporating ITS into transportation planning : phase 1 final report

DOT National Transportation Integrated Search

2000-04-01

Incident management is the process of managing multi-agency, multi-jurisdictional responses to highway traffic disruptions. Traffic incidents are a major cause of congestion on the nation?s highway network. More than half of all freeway traffic conge...

Traffic flow simulation for an urban freeway corridor

DOT National Transportation Integrated Search

1998-01-01

The objective of this paper is to develop a realistic and operational macroscopic traffic flow simulation model which requires relatively less data collection efforts. Such a model should be capable of delineating the dynamics of traffic flow created...

Modeling secondary accidents identified by traffic shock waves.

PubMed

Junhua, Wang; Boya, Liu; Lanfang, Zhang; Ragland, David R

2016-02-01

The high potential for occurrence and the negative consequences of secondary accidents make them an issue of great concern affecting freeway safety. Using accident records from a three-year period together with California interstate freeway loop data, a dynamic method for more accurate classification based on the traffic shock wave detecting method was used to identify secondary accidents. Spatio-temporal gaps between the primary and secondary accident were proven be fit via a mixture of Weibull and normal distribution. A logistic regression model was developed to investigate major factors contributing to secondary accident occurrence. Traffic shock wave speed and volume at the occurrence of a primary accident were explicitly considered in the model, as a secondary accident is defined as an accident that occurs within the spatio-temporal impact scope of the primary accident. Results show that the shock waves originating in the wake of a primary accident have a more significant impact on the likelihood of a secondary accident occurrence than the effects of traffic volume. Primary accidents with long durations can significantly increase the possibility of secondary accidents. Unsafe speed and weather are other factors contributing to secondary crash occurrence. It is strongly suggested that when police or rescue personnel arrive at the scene of an accident, they should not suddenly block, decrease, or unblock the traffic flow, but instead endeavor to control traffic in a smooth and controlled manner. Also it is important to reduce accident processing time to reduce the risk of secondary accident. Copyright © 2015 Elsevier Ltd. All rights reserved.

Concept of operations and policy implications for unmanned aircraft systems use for traffic incident management (UAS-TIM) : final report.

DOT National Transportation Integrated Search

2017-03-01

Texas freeways experience considerable traffic congestionsome from high traffic volumes and some from traffic incidents, both minor (e.g., crashes, stalls, and road debris) and major (e.g., vehicle rollovers, chemical spills, flooding, and hurrica...

Development of a Traffic Management Decision Support Tool for Freeway Incident Traffic Management (FITM) Plan Deployment : Research Summary

DOT National Transportation Integrated Search

2017-12-01

In designing an effective traffic management plan for non-recurrent congestion, it is critical for responsible highway agencies to have some vital information, such as estimated incident duration, resulting traffic queues, and the expected delays. Ov...

Development of a queue warning system utilizing ATM infrastructure system development and field-testing : final report.

DOT National Transportation Integrated Search

2017-06-13

MnDOT has already deployed an extensive infrastructure for Active Traffic Management (ATM) on I-35W and I-94 with plans to expand on other segments of the Twin Cities freeway network. The ATM system includes intelligent lane control signals (ILCS) sp...

Simulation-based decision-making tool for adaptive traffic signal control on Tarrytown Road in the City of White Plains.

DOT National Transportation Integrated Search

2013-01-01

Transportation corridors are vital for our region and even the nations economy and quality of life. A corridor is usually a complicated system that may span multi-jurisdictions, contains multiple modes, include both freeways and local arterials, a...

Public opinion and understanding of advance warning arrow displays used in short-term, mobile, and moving work zones.

DOT National Transportation Integrated Search

2008-03-01

"In long-term work zones on multilane highways and/or freeways, the Federal Highway Administration has interpreted the : Manual on Uniform Traffic Control Devices to mean that only one advance warning arrow displays can be used to denote : the closur...

Effects of roadside memorials on traffic flow.

PubMed

Tay, Richard; Churchill, Anthony; de Barros, Alexandre G

2011-01-01

Despite their growing popularity in North America, little research has been conducted on understanding the effects of roadside memorials on drivers' behaviour. In this study, we examined the short-term effects of roadside memorials on traffic speed and headways on a high speed intercity freeway as well as its long-term effect on traffic speed on a high speed urban freeway. Our study found that the placement of roadside memorials did not have any significant effect on traffic speeds or headways, either in the short or long term. Therefore, concerns about the negative effects on driver behaviour were not supported by this research, at least with regards to speeding and following too closely. However, no positive effects on safety were found either. Copyright © 2010 Elsevier Ltd. All rights reserved.

Analysis of factors associated with traffic injury severity on rural roads in Iran.

PubMed

Kashani, Ali Tavakoli; Shariat-Mohaymany, Afshin; Ranjbari, Andishe

2012-01-01

Iran is a country with one of the highest rates of traffic crash fatality and injury, and seventy percent of these fatalities happen on rural roads. The objective of this study is to identify the significant factors influencing injury severity among drivers involved in crashes on two kinds of major rural roads in Iran: two-lane, two-way roads and freeways. According to the dataset, 213569 drivers were involved in rural road crashes in Iran, over the 3 years from 2006 to 2008. The Classification And Regression Tree method (CART) was applied for 13 independent variables, and one target variable of injury severity with 3 classes of no-injury, injury and fatality. Some of the independent variables were cause of crash, collision type, weather conditions, road surface conditions, driver's age and gender and seat belt usage. The CART model was trained by 70% of these data, and tested with the rest. It was indicated that seat belt use is the most important safety factor for two-lane, two-way rural roads, but on freeways, the importance of this variable is less. Cause of crash, also turned out to be the next most important variable. The results showed that for two-lane, two-way rural roads, "improper overtaking" and "speeding", and for rural freeways, "inattention to traffic ahead", "vehicle defect", and "movement of pedestrians, livestock and unauthorized vehicles on freeways" are the most serious causes of increasing injury severity. The analysis results revealed seat belt use, cause of crash and collision type as the most important variables influencing the injury severity of traffic crashes. To deal with these problems, intensifying police enforcement by means of mobile patrol vehicles, constructing overtaking lanes where necessary, and prohibiting the crossing of pedestrians and livestock and the driving of unauthorized vehicles on freeways are necessary. Moreover, creating a rumble strip on the two edges of roads, and paying attention to the design consistency of roads can be a helpful factor in order to prevent events such as "overturning" and improve the overall safety of freeways.

Bus--carpool FWY lanes in San Francisco area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Newman, L.

1976-11-01

The California Department of Transportation is studying ways to increase the use of the urban freeway systems that will accommodate the maximum number of people with the least delay and the maximum possible safety in a cost-effective way. This paper describes operational features of four different projects under way, namely: a contraflow bus lane; a part-time bus lane in the same direction and unseparated from normal traffic; a bus-carpool lane also in the same direction and unseparated from normal traffic; and a preferential access to a metered freeway. (MCW)

An analysis on the impact of rubbernecking on urban freeway traffic.

DOT National Transportation Integrated Search

2004-08-01

An incident influences traffic not only in the incident direction but also in the : opposite direction. There has been research on the influence of incidents on the traffic in : the incident direction. However, research relating to the influence on t...

Empirical observation of the impact of traffic oscillations on freeway safety : final report, OTREC-RR-10-13, September 2010.

DOT National Transportation Integrated Search

2010-09-01

Traffic oscillations are typical features of congested traffic flow that are characterized by recurring decelerations : followed by accelerations (stop-and-go driving). The negative environmental impacts of these oscillations are widely : accepted, b...

Development of active traffic management strategies for Minnesota freeway corridors : final report.

DOT National Transportation Integrated Search

2015-06-01

In this study, the effectiveness of the I-35W variable advisory speed limit system on the improvement of the traffic : flow was evaluated with the real traffic data. The analysis results indicate there was significant reduction in the : average maxim...

Traveling waves in an optimal velocity model of freeway traffic.

PubMed

Berg, P; Woods, A

2001-03-01

Car-following models provide both a tool to describe traffic flow and algorithms for autonomous cruise control systems. Recently developed optimal velocity models contain a relaxation term that assigns a desirable speed to each headway and a response time over which drivers adjust to optimal velocity conditions. These models predict traffic breakdown phenomena analogous to real traffic instabilities. In order to deepen our understanding of these models, in this paper, we examine the transition from a linear stable stream of cars of one headway into a linear stable stream of a second headway. Numerical results of the governing equations identify a range of transition phenomena, including monotonic and oscillating travelling waves and a time- dependent dispersive adjustment wave. However, for certain conditions, we find that the adjustment takes the form of a nonlinear traveling wave from the upstream headway to a third, intermediate headway, followed by either another traveling wave or a dispersive wave further downstream matching the downstream headway. This intermediate value of the headway is selected such that the nonlinear traveling wave is the fastest stable traveling wave which is observed to develop in the numerical calculations. The development of these nonlinear waves, connecting linear stable flows of two different headways, is somewhat reminiscent of stop-start waves in congested flow on freeways. The different types of adjustments are classified in a phase diagram depending on the upstream and downstream headway and the response time of the model. The results have profound consequences for autonomous cruise control systems. For an autocade of both identical and different vehicles, the control system itself may trigger formations of nonlinear, steep wave transitions. Further information is available [Y. Sugiyama, Traffic and Granular Flow (World Scientific, Singapore, 1995), p. 137].

Traveling waves in an optimal velocity model of freeway traffic

NASA Astrophysics Data System (ADS)

Berg, Peter; Woods, Andrew

2001-03-01

Car-following models provide both a tool to describe traffic flow and algorithms for autonomous cruise control systems. Recently developed optimal velocity models contain a relaxation term that assigns a desirable speed to each headway and a response time over which drivers adjust to optimal velocity conditions. These models predict traffic breakdown phenomena analogous to real traffic instabilities. In order to deepen our understanding of these models, in this paper, we examine the transition from a linear stable stream of cars of one headway into a linear stable stream of a second headway. Numerical results of the governing equations identify a range of transition phenomena, including monotonic and oscillating travelling waves and a time- dependent dispersive adjustment wave. However, for certain conditions, we find that the adjustment takes the form of a nonlinear traveling wave from the upstream headway to a third, intermediate headway, followed by either another traveling wave or a dispersive wave further downstream matching the downstream headway. This intermediate value of the headway is selected such that the nonlinear traveling wave is the fastest stable traveling wave which is observed to develop in the numerical calculations. The development of these nonlinear waves, connecting linear stable flows of two different headways, is somewhat reminiscent of stop-start waves in congested flow on freeways. The different types of adjustments are classified in a phase diagram depending on the upstream and downstream headway and the response time of the model. The results have profound consequences for autonomous cruise control systems. For an autocade of both identical and different vehicles, the control system itself may trigger formations of nonlinear, steep wave transitions. Further information is available [Y. Sugiyama, Traffic and Granular Flow (World Scientific, Singapore, 1995), p. 137].

Is vehicle automation enough to prevent crashes? Role of traffic operations in automated driving environments for traffic safety.

PubMed

Jeong, Eunbi; Oh, Cheol; Lee, Seolyoung

2017-07-01

Automated driving systems (ADSs) are expected to prevent traffic accidents caused by driver carelessness on freeways. There is no doubt regarding this safety benefit if all vehicles in the transportation system were equipped with ADSs; however, it is implausible to expect that ADSs will reach 100% market penetration rate (MPR) in the near future. Therefore, the following question arises: 'Can ADSs, which consider only situations in the vicinity of an equipped vehicle, really contribute to a significant reduction in traffic accidents?' To address this issue, the interactions between equipped and unequipped vehicles must be investigated, which is the purpose of this study. This study evaluated traffic safety at different MPRs based on a proposed index to represent the overall rear-end crash risk of the traffic stream. Two approaches were evaluated for adjusting longitudinal vehicle maneuvers: vehicle safety-based maneuvering (VSM), which considers the crash risk of an equipped vehicle and its neighboring vehicles, and traffic safety-based maneuvering (TSM), which considers the overall crash risk in the traffic stream. TSM assumes that traffic operational agencies are able to monitor all the vehicles and to intervene in vehicle maneuvering. An optimization process, which attempts to obtain vehicle maneuvering control parameters to minimize the overall crash risk, is integrated into the proposed evaluation framework. The main purpose of employing the optimization process for vehicle maneuvering in this study is to identify opportunities to improve traffic safety through effective traffic management rather than developing a vehicle control algorithm that can be implemented in practice. The microscopic traffic simulator VISSIM was used to simulate the freeway traffic stream and to conduct systematic evaluations based on the proposed methodology. Both TSM and VSM achieved significant reductions in the potential for rear-end crashes. However, TSM obtained much greater reductions when the MPR was greater than 50%. This study should inspire transportation researchers and engineers to develop effective traffic operations strategies for automated driving environments. Copyright © 2017. Published by Elsevier Ltd.

Development of a Traffic Management Decision Support Tool for Freeway Incident Traffic Management (FITM) Plan Deployment

DOT National Transportation Integrated Search

2017-12-01

Traffic incidents have long been recognized as the main contributor to congestion in highway networks. Thus, contending with non-recurrent congestion has been a priority task for most highway agencies over the past decades. Under most incident scenar...

Development of prototype decision support systems for real-time freeway traffic routing. Volume I.

DOT National Transportation Integrated Search

1998-01-01

For a traffic management system (TMS) to improve traffic flow, TMS operators must develop effective routing strategies based on the data collected by the system. The purpose of this research was to build prototype decision support systems (DSS) for t...

Modeling vehicle interior noise exposure dose on freeways: Considering weaving segment designs and engine operation.

PubMed

Li, Qing; Qiao, Fengxiang; Yu, Lei; Shi, Junqing

2018-06-01

Vehicle interior noise functions at the dominant frequencies of 500 Hz below and around 800 Hz, which fall into the bands that may impair hearing. Recent studies demonstrated that freeway commuters are chronically exposed to vehicle interior noise, bearing the risk of hearing impairment. The interior noise evaluation process is mostly conducted in a laboratory environment. The test results and the developed noise models may underestimate or ignore the noise effects from dynamic traffic and road conditions and configuration. However, the interior noise is highly associated with vehicle maneuvering. The vehicle maneuvering on a freeway weaving segment is more complex because of its nature of conflicting areas. This research is intended to explore the risk of the interior noise exposure on freeway weaving segments for freeway commuters and to improve the interior noise estimation by constructing a decision tree learning-based noise exposure dose (NED) model, considering weaving segment designs and engine operation. On-road driving tests were conducted on 12 subjects on State Highway 288 in Houston, Texas. On-board Diagnosis (OBD) II, a smartphone-based roughness app, and a digital sound meter were used to collect vehicle maneuvering and engine information, International Roughness Index, and interior noise levels, respectively. Eleven variables were obtainable from the driving tests, including the length and type of a weaving segment, serving as predictors. The importance of the predictors was estimated by their out-of-bag-permuted predictor delta errors. The hazardous exposure level of the interior noise on weaving segments was quantified to hazard quotient, NED, and daily noise exposure level, respectively. Results showed that the risk of hearing impairment on freeway is acceptable; the interior noise level is the most sensitive to the pavement roughness and is subject to freeway configuration and traffic conditions. The constructed NED model shows high predictive power (R = 0.93, normalized root-mean-square error [NRMSE] < 6.7%). Vehicle interior noise is usually ignored in the public, and its modeling and evaluation are generally conducted in a laboratory environment, regardless of the interior noise effects from dynamic traffic, road conditions, and road configuration. This study quantified the interior exposure dose on freeway weaving segments, which provides freeway commuters with a sense of interior noise exposure risk. In addition, a bagged decision tree-based interior noise exposure dose model was constructed, considering vehicle maneuvering, vehicle engine operational information, pavement roughness, and weaving segment configuration. The constructed model could significantly improve the interior noise estimation for road engineers and vehicle manufactures.

Guidelines for freeway lighting curfews.

DOT National Transportation Integrated Search

2012-10-01

Roadway lighting is provided on selected highways to improve the visibility of the nighttime environment. : Roadway lighting is typically warranted on the basis of the daily traffic volume. However, in the earlymorning : hours, the traffic volumes ma...

Freeway travel speed calculation model based on ETC transaction data.

PubMed

Weng, Jiancheng; Yuan, Rongliang; Wang, Ru; Wang, Chang

2014-01-01

Real-time traffic flow operation condition of freeway gradually becomes the critical information for the freeway users and managers. In fact, electronic toll collection (ETC) transaction data effectively records operational information of vehicles on freeway, which provides a new method to estimate the travel speed of freeway. First, the paper analyzed the structure of ETC transaction data and presented the data preprocess procedure. Then, a dual-level travel speed calculation model was established under different levels of sample sizes. In order to ensure a sufficient sample size, ETC data of different enter-leave toll plazas pairs which contain more than one road segment were used to calculate the travel speed of every road segment. The reduction coefficient α and reliable weight θ for sample vehicle speed were introduced in the model. Finally, the model was verified by the special designed field experiments which were conducted on several freeways in Beijing at different time periods. The experiments results demonstrated that the average relative error was about 6.5% which means that the freeway travel speed could be estimated by the proposed model accurately. The proposed model is helpful to promote the level of the freeway operation monitoring and the freeway management, as well as to provide useful information for the freeway travelers.

What have we learned about intelligent transportation systems? Chapter 6, What have we learned about ITS for commercial vehicle operations? Status, challenges, and benefits of CVISN level 1 deployment

DOT National Transportation Integrated Search

2006-01-01

This handbook provides guidance and recommended practices on managing and controlling traffic on ramps with freeway facilities. The use or application of the guidance and recommendations provided will in time serve to enhance the use and effectivenes...

Speed harmonization and peak-period shoulder use to manage urban freeway congestion.

DOT National Transportation Integrated Search

2009-10-01

Traffic congestion is an increasing problem in the nations urban areas, leading to personal inconvenience, : increased pollution, hampered economic productivity, and reduced quality of life. While traffic congestion tends : to continuously increas...

Inspections of Interstate Commercial Vehicles 1994

DOT National Transportation Integrated Search

1974-01-01

The objective of this effort was to complete the development of the computer simulation model SCOT (Simulation of Corridor Traffic) designed to represent traffic flow on an urban grid-freeway integrated highway system by simulating an existing system...

Assessing the performance of the SpeedInfo sensor.

DOT National Transportation Integrated Search

2013-12-01

Until recently freeway traffic operations data were collected in house by the Ohio Department of : Transportation (ODOT) using loop detectors. In recent years several private companies have emerged with a : viable opportunity to outsource traffic dat...

Assessing rear-end collision risk of cars and heavy vehicles on freeways using a surrogate safety measure.

PubMed

Zhao, Peibo; Lee, Chris

2018-04-01

This study analyzes rear-end collision risk of cars and heavy vehicles on freeways using a surrogate safety measure. The crash potential index (CPI) was modified to reflect driver's reaction time and estimated by types of lead and following vehicles (car or heavy vehicle). CPIs were estimated using the individual vehicle trajectory data from a segment of the US-101 freeway in Los Angeles, U.S.A. It was found that the CPI was generally higher for the following heavy vehicle than the following car due to heavy vehicle's lower braking capability. This study also validates the CPI using the simulated traffic data which replicate the observed traffic conditions a few minutes before the crash time upstream and downstream of the crash locations. The observed data were obtained from crash records and loop detectors on a section of the Gardiner Expressway in Toronto, Canada. The result shows that the values of CPI were consistently higher during the traffic conditions immediately before the crash time (crash case) than the normal traffic conditions (non-crash case). This demonstrates that the CPI can be used to capture rear-end collision risk during car-following maneuver on freeways. The result also shows that rear-end collision risk is lower for heavy vehicles than cars in the crash case due to their shorter reaction time and lower speed when spacing is shorter. Thus, it is important to reflect the differences in driver behavior and vehicle performance characteristics between cars and heavy vehicles in estimating surrogate safety measures. Lastly, it was found that the CPI-based crash prediction model can correctly identify the crash and non-crash cases at higher accuracy than the other crash prediction models based on detectors. Copyright © 2018 Elsevier Ltd. All rights reserved.

Using temporal detrending to observe the spatial correlation of traffic.

PubMed

Ermagun, Alireza; Chatterjee, Snigdhansu; Levinson, David

2017-01-01

This empirical study sheds light on the spatial correlation of traffic links under different traffic regimes. We mimic the behavior of real traffic by pinpointing the spatial correlation between 140 freeway traffic links in a major sub-network of the Minneapolis-St. Paul freeway system with a grid-like network topology. This topology enables us to juxtapose the positive and negative correlation between links, which has been overlooked in short-term traffic forecasting models. To accurately and reliably measure the correlation between traffic links, we develop an algorithm that eliminates temporal trends in three dimensions: (1) hourly dimension, (2) weekly dimension, and (3) system dimension for each link. The spatial correlation of traffic links exhibits a stronger negative correlation in rush hours, when congestion affects route choice. Although this correlation occurs mostly in parallel links, it is also observed upstream, where travelers receive information and are able to switch to substitute paths. Irrespective of the time-of-day and day-of-week, a strong positive correlation is witnessed between upstream and downstream links. This correlation is stronger in uncongested regimes, as traffic flow passes through consecutive links more quickly and there is no congestion effect to shift or stall traffic. The extracted spatial correlation structure can augment the accuracy of short-term traffic forecasting models.

Using temporal detrending to observe the spatial correlation of traffic

PubMed Central

2017-01-01

This empirical study sheds light on the spatial correlation of traffic links under different traffic regimes. We mimic the behavior of real traffic by pinpointing the spatial correlation between 140 freeway traffic links in a major sub-network of the Minneapolis—St. Paul freeway system with a grid-like network topology. This topology enables us to juxtapose the positive and negative correlation between links, which has been overlooked in short-term traffic forecasting models. To accurately and reliably measure the correlation between traffic links, we develop an algorithm that eliminates temporal trends in three dimensions: (1) hourly dimension, (2) weekly dimension, and (3) system dimension for each link. The spatial correlation of traffic links exhibits a stronger negative correlation in rush hours, when congestion affects route choice. Although this correlation occurs mostly in parallel links, it is also observed upstream, where travelers receive information and are able to switch to substitute paths. Irrespective of the time-of-day and day-of-week, a strong positive correlation is witnessed between upstream and downstream links. This correlation is stronger in uncongested regimes, as traffic flow passes through consecutive links more quickly and there is no congestion effect to shift or stall traffic. The extracted spatial correlation structure can augment the accuracy of short-term traffic forecasting models. PMID:28472093

Alternative approaches to condition monitoring in freeway management systems.

DOT National Transportation Integrated Search

2002-01-01

In response to growing concerns over traffic congestion, traffic management systems have been built in large urban areas in an effort to improve the efficiency and safety of the transportation network. This research effort developed an automated cond...

Estimation of Traffic Variables Using Point Processing Techniques

DOT National Transportation Integrated Search

1978-05-01

An alternative approach to estimating aggregate traffic variables on freeways--spatial mean velocity and density--is presented. Vehicle arrival times at a given location on a roadway, typically a presence detector, are regarded as a point or counting...

Propagation of Disturbances in Traffic Flow

DOT National Transportation Integrated Search

1977-09-01

The system-optimized static traffic-assignment problem in a freeway corridor network is the problem of choosing a distribution of vehicles in the network to minimize average travel time. It is of interest to know how sensitive the optimal steady-stat...

Wide area detection system: Conceptual design study. [using television and microelectronic technology

NASA Technical Reports Server (NTRS)

Hilbert, E. E.; Carl, C.; Goss, W.; Hansen, G. R.; Olsasky, M. J.; Johnston, A. R.

1978-01-01

An integrated sensor for traffic surveillance on mainline sections of urban freeways is described. Applicable imaging and processor technology is surveyed and the functional requirements for the sensors and the conceptual design of the breadboard sensors are given. Parameters measured by the sensors include lane density, speed, and volume. The freeway image is also used for incident diagnosis.

Information on estimating local government highway bonds

DOT National Transportation Integrated Search

1973-06-01

The theory of traffic flow following a lane blockage on a multi-lane freeway has been developed. Numerical results have been obtained and are presented both for the steady state case where the traffic density remains constant and the non-steady state...

Evaluating Environmental Impact of Traffic Congestion in Real Time Based on Sparse Mobile Crowd-sourced Data

DOT National Transportation Integrated Search

2018-02-02

Traffic congestion at arterial intersections and freeway bottlenecks degrades the air quality and threatens the public health. Conventionally, air pollutants are monitored by sparsely-distributed Quality Assurance Air Monitoring Sites. Sparse mobile ...

Development of decision support systems for real-time freeway traffic routing : volume II.

DOT National Transportation Integrated Search

1998-01-01

Real-time traffic flow routing is a promising approach to alleviating congestion. Existing approaches to developing real-time routing strategies, however, have limitations. This study explored the potential for using case-based reasoning (CBR), an em...

Impacts of freeway traffic conditions on in-vehicle exposure to ultrafine particulate matter

NASA Astrophysics Data System (ADS)

Bigazzi, Alexander Y.; Figliozzi, Miguel A.

2012-12-01

There is evidence of adverse health impacts from human exposure to traffic-related ultrafine particulate matter pollution. As more commuters are spending a significant portion of their daily routine inside vehicles, it is increasingly relevant to study exposure levels to harmful pollutants inside the vehicle microenvironment. This study is one of the first research efforts to combine detailed freeway traffic data (at 20 s intervals) and in-vehicle ultrafine particulate (UFP) exposure data under varying vehicle ventilation conditions. Results show that due to negative correlation between traffic speed and density, traffic states have a small but significant impact on in-vehicle UFP concentrations, highest in high traffic flow-high speed conditions or in high traffic density-low speed conditions. Vehicle cabin barrier effects are the primary determinant of in-vehicle exposure concentrations, providing 15% protection with the windows down, 47% protection with the windows up and the vent open, and 83-90% protection with the windows up and the vent closed (more with the air conditioning on). Unique results from this study include the dominance of ventilation over traffic effects on UFP and the non-linear relationships between traffic variables and UFP concentrations. The results of this research have important implications for exposure modeling and potential exposure mitigation strategies.

Development of a guideline for work zone diversion rate and capacity reduction.

DOT National Transportation Integrated Search

2016-03-01

This study develops a comprehensive guideline to estimate the traffic diversion rates and capacity reduction for : work zones. The analysis of the traffic diversion patterns with data from past work zones in the metro freeway : network in Minnesota r...

Examination of fundamental traffic characteristics and implications to ITS

DOT National Transportation Integrated Search

1998-01-01

The purpose of this paper is to study and analyze the essential traffic characteristics of a 5.4-mile stretch of I-64-40 located within the St. Louis metropolitan area. The freeway experiences heavy congestion during peak periods attributed to factor...

Examining the speed-flow-delay paradox in the Washington, DC region : potential impacts of reduced traffic on congestion delay and potential for reductions in discretionary travel during peak periods.

DOT National Transportation Integrated Search

2008-12-01

Traffic congestion in the Washington, DC area, especially congestion on our freeways, costs our residents every day : in terms of wasted time, fuel, and increased air pollution. Highway studies have determined that once traffic volumes : exceed the c...

Transferability and robustness of real-time freeway crash risk assessment.

PubMed

Shew, Cameron; Pande, Anurag; Nuworsoo, Cornelius

2013-09-01

This study examines the data from single loop detectors on northbound (NB) US-101 in San Jose, California to estimate real-time crash risk assessment models. The classification tree and neural network based crash risk assessment models developed with data from NB US-101 are applied to data from the same freeway, as well as to the data from nearby segments of the SB US-101, NB I-880, and SB I-880 corridors. The performance of crash risk assessment models on these nearby segments is the focus of this research. The model applications show that it is in fact possible to use the same model for multiple freeways, as the underlying relationships between traffic data and crash risk remain similar. The framework provided here may be helpful to authorities for freeway segments with newly installed traffic surveillance apparatuses, since the real-time crash risk assessment models from nearby freeways with existing infrastructure would be able to provide a reasonable estimate of crash risk. The robustness of the model output is also assessed by location, time of day, and day of week. The analysis shows that on some locations the models may require further learning due to higher than expected false positive (e.g., the I-680/I-280 interchange on US-101 NB) or false negative rates. The approach for post-processing the results from the model provides ideas to refine the model prior to or during the implementation. Copyright © 2013 National Safety Council and Elsevier Ltd. All rights reserved.

Optimal signal timing design for urban street networks under user equilibrium based traffic conditions : final report.

DOT National Transportation Integrated Search

2016-09-20

In the ever-growing travel demand, traffic congestion on freeways and expressways : recurs more frequently at a higher number of locations and for longer durations with : added severity. This becomes especially true in large metropolitan areas. Parti...

Assessing segment- and corridor-based travel-time reliability on urban freeways tech transfer summary : tech transfer summary.

DOT National Transportation Integrated Search

2016-09-01

Travel time and travel-time reliability have been used as performance : measures to evaluate traffic system conditions and develop advanced : traveler information and traffic management systems. The objectives of this research were to: : - Quantify s...

The Santa Monica freeway diamond lanes. Volume I. Summary. Final report, March 1976-August 1976

DOE Office of Scientific and Technical Information (OSTI.GOV)

Billheimer, J.W.; Bullemer, R.J.; Fratessa, C.

1977-09-01

The Santa Monica Freeway Diamond Lanes, a pair of concurrent-flow preferential lanes for buses and carpools linking the City of Santa Monica, California, with the Los Angeles CBD, opened on March 16, 1976 and operated amid much controversy for 21 weeks until the U.S. District Court halted the project. The Diamond Lane project marked the first time preferential lanes had been created by taking busy freeway lanes out of existing service and dedicating them to the exclusive use of high-occupancy vehicles. This report summarizes the findings of the evaluation of the project. The report addresses a broad range of impactsmore » in the following major areas: Traffic speeds and travel times; traffic volumes and carpool information; bus operations and ridership; safety and enforcement; energy and air quality; and public attitudes and response. Analysis shows that the project succeeded in increasing carpool ridership by 65% and the increased bus service accompanying the Diamond Lanes caused bus ridership to more than triple. Nonetheless, energy savings and air quality improvements were insignificant, freeway accidents increased significantly, non-carpoolers lost far more time than carpoolers gained, and a heated public outcry developed which has delayed the implementation of other preferential treatment projects in S. California.« less

Life Times of Simulated Traffic Jams

NASA Astrophysics Data System (ADS)

Nagel, Kai

We study a model for freeway traffic which includes strong noise taking into account the fluctuations of individual driving behavior. The model shows emergent traffic jams with a self-similar appearance near the throughput maximum of the traffic. The lifetime distribution of these jams shows a short scaling regime, which gets considerably longer if one reduces the fluctuations when driving at maximum speed but leaves the fluctuations for slowing down or accelerating unchanged. The outflow from a traffic jam self-organizes into this state of maximum throughput.

Phase II, improved work zone design guidelines and enhanced model of traffic delays in work zones : final report, March 2009.

DOT National Transportation Integrated Search

2009-03-01

This project contains three major parts. In the first part a digital computer simulation model was developed with the aim to model the traffic through a freeway work zone situation. The model was based on the Arena simulation software and used cumula...

Phase II, improved work zone design guidelines and enhanced model of traffic delays in work zones : executive summary report.

DOT National Transportation Integrated Search

2009-03-01

This project contains three major parts. In the first part a digital computer simulation model was developed with the aim to model the traffic through a freeway work zone situation. The model was based on the Arena simulation software and used cumula...

Final report : federal earmark ITS-9851(003) : Virginia Department of Transportation : Northern Virginia smart traffic center video quality improvement program

DOT National Transportation Integrated Search

2005-08-01

Like many freeway traffic management systems around the country, the NOVA STC system was implemented in phases over a period of years. As a result, some field components had reached their maximum life cycle, including a portion of the CCTV subsystem....

Development of a real-time crash risk prediction model incorporating the various crash mechanisms across different traffic states.

PubMed

Xu, Chengcheng; Wang, Wei; Liu, Pan; Zhang, Fangwei

2015-01-01

This study aimed to identify the traffic flow variables contributing to crash risks under different traffic states and to develop a real-time crash risk model incorporating the varying crash mechanisms across different traffic states. The crash, traffic, and geometric data were collected on the I-880N freeway in California in 2008 and 2009. This study considered 4 different traffic states in Wu's 4-phase traffic theory. They are free fluid traffic, bunched fluid traffic, bunched congested traffic, and standing congested traffic. Several different statistical methods were used to accomplish the research objective. The preliminary analysis showed that traffic states significantly affected crash likelihood, collision type, and injury severity. Nonlinear canonical correlation analysis (NLCCA) was conducted to identify the underlying phenomena that made certain traffic states more hazardous than others. The results suggested that different traffic states were associated with various collision types and injury severities. The matching of traffic flow characteristics and crash characteristics in NLCCA revealed how traffic states affected traffic safety. The logistic regression analyses showed that the factors contributing to crash risks were quite different across various traffic states. To incorporate the varying crash mechanisms across different traffic states, random parameters logistic regression was used to develop a real-time crash risk model. Bayesian inference based on Markov chain Monte Carlo simulations was used for model estimation. The parameters of traffic flow variables in the model were allowed to vary across different traffic states. Compared with the standard logistic regression model, the proposed model significantly improved the goodness-of-fit and predictive performance. These results can promote a better understanding of the relationship between traffic flow characteristics and crash risks, which is valuable knowledge in the pursuit of improving traffic safety on freeways through the use of dynamic safety management systems.

Evaluation of the traffic safety benefits of a lower speed limit and restriction of trucks to use of right lane only on I-10 over the Atchafalaya Basin.

DOT National Transportation Integrated Search

2012-01-01

To improve traffic operation and safety, several states have implemented truck lane restriction and differential speed limit policies on freeways. In response to an 11-vehicle crash in September 2003, the Louisiana State Department of Transportation ...

Building the vision, a series of AZTech ITS model deployment success stories for the Phoenix metropolitan area : number three : well connected, linking U.S. highway 60 with the trailmaster system

DOT National Transportation Integrated Search

1998-01-01

The Arizona Department of Transportation's (ADOT) Trailmaster Freeway Management System is integral to AZTech. Trailmaster provides state-of-the-art traffic management through a variety of electronic means, such as collecting and distributing traffic...

Understanding characteristics in multivariate traffic flow time series from complex network structure

NASA Astrophysics Data System (ADS)

Yan, Ying; Zhang, Shen; Tang, Jinjun; Wang, Xiaofei

2017-07-01

Discovering dynamic characteristics in traffic flow is the significant step to design effective traffic managing and controlling strategy for relieving traffic congestion in urban cities. A new method based on complex network theory is proposed to study multivariate traffic flow time series. The data were collected from loop detectors on freeway during a year. In order to construct complex network from original traffic flow, a weighted Froenius norm is adopt to estimate similarity between multivariate time series, and Principal Component Analysis is implemented to determine the weights. We discuss how to select optimal critical threshold for networks at different hour in term of cumulative probability distribution of degree. Furthermore, two statistical properties of networks: normalized network structure entropy and cumulative probability of degree, are utilized to explore hourly variation in traffic flow. The results demonstrate these two statistical quantities express similar pattern to traffic flow parameters with morning and evening peak hours. Accordingly, we detect three traffic states: trough, peak and transitional hours, according to the correlation between two aforementioned properties. The classifying results of states can actually represent hourly fluctuation in traffic flow by analyzing annual average hourly values of traffic volume, occupancy and speed in corresponding hours.

Connected vehicle freeway speed harmonization systems.

DOT National Transportation Integrated Search

2016-03-15

The capacity drop phenomenon, which reduces the maximum bottleneck discharge rate following the onset of congestion, is a critical restriction in transportation networks that causes additional traffic congestion. Consequently, preventing or reducing ...

Reducing the risk of rear-end collisions with infrastructure-to-vehicle (I2V) integration of variable speed limit control and adaptive cruise control system.

PubMed

Li, Ye; Wang, Hao; Wang, Wei; Liu, Shanwen; Xiang, Yun

2016-08-17

Adaptive cruise control (ACC) has been investigated recently to explore ways to increase traffic capacity, stabilize traffic flow, and improve traffic safety. However, researchers seldom have studied the integration of ACC and roadside control methods such as the variable speed limit (VSL) to improve safety. The primary objective of this study was to develop an infrastructure-to-vehicle (I2V) integrated system that incorporated both ACC and VSL to reduce rear-end collision risks on freeways. The intelligent driver model was firstly modified to simulate ACC behavior and then the VSL strategy used in this article was introduced. Next, the I2V system was proposed to integrate the 2 advanced techniques, ACC and VSL. Four scenarios of no control, VSL only, ACC only, and the I2V system were tested in simulation experiments. Time exposed time to collision (TET) and time integrated time to collision (TIT), 2 surrogate safety measures derived from time to collision (TTC), were used to evaluate safety issues associated with rear-end collisions. The total travel times of each scenario were also compared. The simulation results indicated that both the VSL-only and ACC-only methods had a positive impact on reducing the TET and TIT values (reduced by 53.0 and 58.6% and 59.0 and 65.3%, respectively). The I2V system combined the advantages of both ACC and VSL to achieve the most safety benefits (reduced by 71.5 and 77.3%, respectively). Sensitivity analysis of the TTC threshold also showed that the I2V system obtained the largest safety benefits with all of the TTC threshold values. The impact of different market penetration rates of ACC vehicles in I2V system indicated that safety benefits increase with an increase in ACC proportions. Compared to VSL-only and ACC-only scenarios, this integrated I2V system is more effective in reducing rear-end collision risks. The findings of this study provide useful information for traffic agencies to implement novel techniques to improve safety on freeways.

Quantifying travel time variability in transportation networks.

DOT National Transportation Integrated Search

2010-03-01

Nonrecurring congestion creates significant delay on freeways in urban areas, lending importance : to the study of facility reliability. In locations where traffic detectors record and archive data, : approximate probability distributions for travel ...

Evidence for the accumulation of atmospheric lead by insects in areas of high traffic density

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giles, F.E.; Middleton, S.G.; Grau, J.G.

1973-04-01

This study followed the path of lead through an insect food chain. The site chosen was 4 km north of the city of Baltimore, adjacent to a major freeway. The lead content of various specimens was assayed. Higher concentrations of Pb found in wild carrot and evening primrose that grew near the freeway indicated that the conditions in the test area were similar to those of land adjacent to high density thoroughfares reported earlier. These plants were hosts for Japanese beetles. The damselfly collected showed higher concentrations in July, but less in August; therefore no significant differences. The most strikingmore » differences in lead concentration were exhibited by the European mantid. All freeway samples of the species showed significantly higher concentrations of lead than control samples, but nymphs collected on August 13 had higher concentrations than did samples of teneral images taken August 31. Lead might possibly be stored in the exoskeleton, which upon being shed would cause a lower lead reading. It was presumed that measurable amounts of atmospheric lead are being concentrated by insect predators, at least during the later part of the season. 5 references, 1 table.« less

HOV Lane Violation Study

DOT National Transportation Integrated Search

1990-01-01

In an attempt to cope with the traffic congestion caused by the rapid growth of : suburban populations and the relative decline in funds and space for additional : freeway construction, the California Department of Transportation (CALTRANS) has : int...

Traffic Games: Modeling Freeway Traffic with Game Theory

PubMed Central

Cortés-Berrueco, Luis E.; Gershenson, Carlos; Stephens, Christopher R.

2016-01-01

We apply game theory to a vehicular traffic model to study the effect of driver strategies on traffic flow. The resulting model inherits the realistic dynamics achieved by a two-lane traffic model and aims to incorporate phenomena caused by driver-driver interactions. To achieve this goal, a game-theoretic description of driver interaction was developed. This game-theoretic formalization allows one to model different lane-changing behaviors and to keep track of mobility performance. We simulate the evolution of cooperation, traffic flow, and mobility performance for different modeled behaviors. The analysis of these results indicates a mobility optimization process achieved by drivers’ interactions. PMID:27855176

Traffic Games: Modeling Freeway Traffic with Game Theory.

PubMed

Cortés-Berrueco, Luis E; Gershenson, Carlos; Stephens, Christopher R

2016-01-01

We apply game theory to a vehicular traffic model to study the effect of driver strategies on traffic flow. The resulting model inherits the realistic dynamics achieved by a two-lane traffic model and aims to incorporate phenomena caused by driver-driver interactions. To achieve this goal, a game-theoretic description of driver interaction was developed. This game-theoretic formalization allows one to model different lane-changing behaviors and to keep track of mobility performance. We simulate the evolution of cooperation, traffic flow, and mobility performance for different modeled behaviors. The analysis of these results indicates a mobility optimization process achieved by drivers' interactions.

Costs and benefits of MDOT intelligent transportation system deployments.

DOT National Transportation Integrated Search

2015-07-01

This report analyses costs and benefits of Intelligent Transportation Systems (ITS) deployed by : the Michigan Department of Transportation (MDOT). MDOT ITS focuses on traffic incident : management and also provide Freeway Courtesy Patrol services. A...

General guidelines for active traffic management deployment : interim report.

DOT National Transportation Integrated Search

2011-08-01

Continued growth in travel in congested freeway corridors and limited public funding for expansion and improvement projects are limiting agencies abilities to provide sufficient roadway capacity in major metropolitan areas. Focusing on trip reliab...

ITS data quality : assessment procedure for freeway point detectors.

DOT National Transportation Integrated Search

2003-01-01

The Virginia Department of Transportation (VDOT) has made significant investments in the traffic-monitoring infrastructure that supports intelligent transportation systems (ITS). The purpose of this infrastructure is to provide accurate, real-time in...

National Traffic Speeds Survey I : 2007

DOT National Transportation Integrated Search

2012-08-01

A field survey was conducted during spring and summer 2007 to measure travel speeds and prepare nationallyrepresentative : speed estimates for all types of motor vehicles on freeways, arterial highways, and collector roads : across the United States....

Acceleration lane design for higher truck volumes.

DOT National Transportation Integrated Search

2008-12-09

The research project examined attributes associated with tractor-trailer trucks accelerating on freeway entry ramps and : entering the main traffic lanes. Data for this project were collected at five commercial vehicle weigh stations in : Arkansas an...

Implementing active traffic management strategies in the U.S.

DOT National Transportation Integrated Search

2010-10-01

Limited public funding for roadway expansion and improvement projects, coupled with continued growth in travel along congested urban freeway corridors, creates a pressing need for innovative congestion management approaches. Strategies to address con...

Evaluation of Two Methods of Prompting Drivers to Use Specific Exits on Conflicts between Vehicles at the Critical Exit

ERIC Educational Resources Information Center

Van Houten, Ron; Malenfant, J. E. Louis; Zhao, Nan; Ko, Byungkon; Van Houten, Jonathan

2005-01-01

The Florida Department of Transportation used a series of changeable-message signs that functioned as freeway guide signs to divert traffic to Universal Theme Park via one of two eastbound exits based on traffic congestion at the first of the two exits. An examination of crashes along the entire route indicated a statistically significant increase…

Development of a lane change risk index using vehicle trajectory data.

PubMed

Park, Hyunjin; Oh, Cheol; Moon, Jaepil; Kim, Seongho

2018-01-01

Surrogate safety measures (SSMs) have been widely used to evaluate crash potential, which is fundamental for the development of effective safety countermeasures. Unlike existing SSMs, which are mainly focused on the evaluation of longitudinal vehicle maneuvering leading to rear-end crashes, this study proposes a new method for estimating crash risk while a subject vehicle changes lanes, referred to as the lane change risk index (LCRI). A novel feature of the proposed methodology is its incorporation of the amount of exposure time to potential crash and the expected crash severity level by applying a fault tree analysis (FTA) to the evaluation framework. Vehicle interactions between a subject vehicle and adjacent vehicles in the starting lane and the target lane are evaluated in terms of crash potential during lane change. Vehicle trajectory data obtained from a traffic stream, photographed using a drone flown over a freeway segment, is used to investigate the applicability of the proposed methodology. This study compares the characteristics of compulsory and discretionary lane changes observed in a work zone section and a general section of a freeway using the LCRI. It is expected that the outcome of this study will be valuable in evaluating the effectiveness of various traffic operations and control strategies in terms of lane change safety. Copyright © 2017 Elsevier Ltd. All rights reserved.

Investigation of freeway operations in metro Detroit.

DOT National Transportation Integrated Search

2011-10-01

Traffic incidents are the primary cause of non-recurrent congestion in urban areas, resulting in : reductions in roadway capacity due to crashes, vehicle breakdowns, and other events. In addition to : contributing to congestion and delay, incidents c...

Evaluation of Incident Detection Methodologies

DOT National Transportation Integrated Search

1999-10-01

Original Report Date: October 1998. The detection of freeway incidents is an essential element of an area's traffic management system. Incidents need to be detected and handled as promptly as possible to minimize delay to the public. Various algorith...

Telecommunications handbook for transportation professionals : the basics of telecommunications.

DOT National Transportation Integrated Search

2004-08-01

This handbook was created to provide individuals responsible for managing and implementing Traffic : Signal, and Freeway Management programs with an understand of the basic technologies of : telecommunications. The handbook provides a brief look at t...

Best practices and outreach for active traffic management : final report.

DOT National Transportation Integrated Search

2011-12-01

Continued growth in travel on congested freeway corridors and limited public funding for : expansion and improvement projects are limiting agencies abilities to provide sufficient roadway : capacity in major metropolitan areas. Focusing on trip re...

Interactive risk analysis on crash injury severity at a mountainous freeway with tunnel groups in China.

PubMed

Huang, Helai; Peng, Yunying; Wang, Jie; Luo, Qizhang; Li, Xiang

2018-02-01

Traffic safety of freeways has attracted major concerns, especially for a mountainous freeway affected by adverse terrain conditions, constrained roadway geometry and complicated driving environments. On the basis of a comprehensive dataset collected from a mountainous freeway with a length of 61km but gathering 12 tunnels, this study seeks to examining the interactive effect of mountainous freeway alignment, driving behaviors, vehicle characteristics and environmental factors on crash severity. A classification and regression tree (CART) model is employed as it can deal with high-order interactions between explanatory variables. Results show that the driving behavior is the most important determinant for injury severity of mountainous freeway crashes, followed by the crash time, grade, curve radius and vehicle type. These variables, interacted with the factors of season and crash location, may largely account for the likelihood of high risk events which may result in severe crashes. Events associated with a notably higher probability of severe crashes include coach drivers involved in improper lane changing and other improper actions, drivers involved in speeding during afternoon or evening, drivers involved in speeding along large curve and straight segment during morning, noon or night, and drivers involved in fatigue while passing along the downgrade. Safety interventions to prevent severe crashes at the mountainous freeway include hierarchical supervision in terms of hazardous driving events, enhanced enforcement for speeding and fatigue driving, deployment of advanced driving assistance systems for fatigue driving warning, and cumulative driving time monitoring for long-distance-travel freight vehicles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Freeway operations analysis of I-80 to I-29 interchange.

DOT National Transportation Integrated Search

1974-01-01

At the request of the Iowa State Highway Commission, the Engineering Research Institute observed the traffic operations at the Interstate 29 (1-29) and Interstate 80 (1-80) interchange in the southwest part of Council Bluffs.

I-880 field experiment : analysis of incident data.

DOT National Transportation Integrated Search

1997-01-01

The I-880 field experiment has produced one of the largest data bases on incidents and freeway traffic-flow characteristics ever compiled. Field data on incidents were collected through observations of probe-vehicle drivers before and after the imple...

Evaluation of temporary ramp metering for work zones.

DOT National Transportation Integrated Search

2012-11-01

Ramp metering has been successfully implemented in many states to improve traffic operations on freeways. Studies have documented the positive mobility and safety benefits of ramp metering. However, there have been no studies on the use of ramp meter...

Reduced lighting on freeways during periods of low traffic density

DOT National Transportation Integrated Search

1995-02-01

Geometry-related effects of changes in truck size and weight regulations include a diverse set of highway design elements related to virtually every aspect of vehicle design and operation. The turning, stopping, acceleration, hill-climbing, and other...

Comparison of methods for measuring travel time at Florida freeways and arterials.

DOT National Transportation Integrated Search

2014-07-01

Travel time is an important performance measure used to assess the traffic operational quality of various types of highway : facilities. Previous research funded by the Florida Department of Transportation (FDOT) on travel time reliability developed,...

Work zone lane closure analysis model.

DOT National Transportation Integrated Search

2009-10-01

At the Alabama Department of Transportation (ALDOT), the tool used by traffic engineers to predict whether a queue will form at a freeway work zone is the Excel-based "Lane Rental Model" developed at the Oklahoma Department of Transportation (OkDOT) ...

Development of a MASH TL-3 median barrier gate.

DOT National Transportation Integrated Search

2011-06-01

Median barriers are commonly used to separate opposing lanes of traffic on divided highways and to : separate managed lanes from general purpose lanes. Concrete median barriers (CMBs) are often preferred : on urban freeways with narrow medians due to...

Mobile platform for overhead detectors of road vehicles.

DOT National Transportation Integrated Search

2002-06-01

The California Department of Transportation (CALTRANS) has a need to monitor traffic flow over freeways. Currently, this is done mainly : through the use of loop detectors. These are measuring devices that are buried under the road pavement, an...

Freeway Traffic Flow Following a Lane Blockage

DOT National Transportation Integrated Search

1996-07-01

As part of the assessment of the development and deployment of ITS products and services in metropolitan areas sponsored by the U.S. Department of Transportations (U.S. DOT) Joint Program Office for ITS, analysts from the Volpe National Transporta...

Evaluation of optimal traffic monitoring station spacing on freeways.

DOT National Transportation Integrated Search

2009-02-01

Results showed that UDOT can reduce the number of detectors currently maintained by TMCs and can deploy far fewer than the mile spacing guidelines. This should result in significant cost savings in capital, operations, and maintenance costs. Fu...

Evaluation of the impacts of cooperative adaptive cruise control on reducing rear-end collision risks on freeways.

PubMed

Li, Ye; Wang, Hao; Wang, Wei; Xing, Lu; Liu, Shanwen; Wei, Xueyan

2017-01-01

Although plenty of studies have been conducted recently about the impacts of cooperative adaptive cruise control (CACC) system on traffic efficiency, there are few researches analyzing the safety effects of this advanced driving-assistant system. Thus, the primary objective of this study is to evaluate the impacts of the CACC system on reducing rear-end collision risks on freeways. The CACC model is firstly developed, which is based on the Intelligent Driver Model (IDM). Then, two surrogated safety measures, derived from the time-to-collision (TTC), denoting time exposed time-to-collision (TET) and time integrated time-to-collision (TIT), are introduced for quantifying the collision risks. And the safety effects are analyzed both theoretically and experimentally, by the linear stability analysis and simulations. The theoretical and simulation results conformably indicate that the CACC system brings dramatic benefits for reducing rear-end collision risks (TET and TIT are reduced more than 90%, respectively), when the desired time headway and time delay are set properly. The sensitivity analysis indicates there are few differences among different values of the threshold of TTC and the length of a CACC platoon. The results also show that the safety improvements weaken with the decrease of the penetration rates of CACC on the market and the increase of time delay between platoons. We also evaluate the traffic efficiency of the CACC system with different desired time headway. Copyright © 2016 Elsevier Ltd. All rights reserved.

Using detector data to identify and examine crashes and incidents on freeways.

DOT National Transportation Integrated Search

2010-09-01

Traffic incidents, such as crashes and vehicular breakdowns, result in reductions in roadway capacity and : are the primary cause of non-recurrent congestion in urban areas. In addition to contributing to : congestion and delay, incidents adversely a...

Using detector data to identify and examine crashes and incidents on freeways

DOT National Transportation Integrated Search

2010-09-01

Traffic incidents, such as crashes and vehicular breakdowns, result in reductions in roadway capacity and are the primary cause of non-recurrent congestion in urban areas. In addition to contributing to congestion and delay, incidents adversely affec...

DIVERT (during incidents vehicles exit to reduce time) : evaluation report

DOT National Transportation Integrated Search

1998-09-01

The goal of DIVERT is to provide management strategies during periods of freeway incidents by routing diverted traffic over city surface arterials in a planned, coordinated manner. Several detailed findings of the evaluation of this project are inclu...

Direct, Operational Field Test Evaluation, Human Factors

DOT National Transportation Integrated Search

1998-08-01

IN THIS EXPERIMENT, 32 LICENSED DRIVERS (16 YOUNG, 16 OLD) DROVE ON AN EXPRESSWAY. ON EACH TRIAL (96 PER SUBJECT), 1 TO 3 TRAFFIC MESSAGES CONTAINING 6 TO 14 ITEMS WERE PRESENTED. (L-94 EASTBOUND AT SOUTHFIELD FREEWAY, CONTINUING CONSTRUCTION, RIGHT ...

Guidelines for reducing wrong-way crashes on freeways.

DOT National Transportation Integrated Search

2014-05-01

Each year, hundreds of fatal wrong-way driving (WWD) crashes occur across the United States, and thousands : of injuries are reported in traffic crashes caused by wrong-way drivers. Although WWD crashes have been a : concern since the advent of acces...

Identifying chronic errors at freeway loop detectors- splashover, pulse breakup, and sensitivity settings.

DOT National Transportation Integrated Search

2011-03-01

Traffic Management applications such as ramp metering, incident detection, travel time prediction, and vehicle : classification greatly depend on the accuracy of data collected from inductive loop detectors, but these data are : prone to various erro...

Technology scan of future traveler information systems and applications in Georgia.

DOT National Transportation Integrated Search

2013-10-01

Statewide traveler information provided in Georgia through its NaviGAtor/5-1-1 system is : primarily based on Intelligent Transportation Systems (ITS) related to freeway traffic : management. The purpose of this study is to evaluate traveler informat...

Simulation analysis of route diversion strategies for freeway incident management : final report.

DOT National Transportation Integrated Search

1995-02-01

The purpose of this project was to investigate whether simulation models could : be used as decision aids for defining traffic diversion strategies for effective : incident management. A methodology was developed for using such a model to : determine...

A Knowledge-based System for Estimating Incident Clearance Duration for Maryland : I-95 a Case Study for the Project of MD-17-SHA/UM/4-19 : “Development of a Traffic Management Decision Support Tool for Freeway Incident Traffic Management (FITM) Plan Deployment”

DOT National Transportation Integrated Search

2017-12-01

For the incident response operations to be appreciated by the general public, it is essential that responsible highway agencies be capable of providing the estimated clearance duration of a detected incident at the level sufficiently reliable for mot...

Study on traffic characteristics for a typical expressway on-ramp bottleneck considering various merging behaviors

NASA Astrophysics Data System (ADS)

Sun, Jie; Li, Zhipeng; Sun, Jian

2015-12-01

Recurring bottlenecks at freeway/expressway are considered as the main cause of traffic congestion in urban traffic system while on-ramp bottlenecks are the most significant sites that may result in congestion. In this paper, the traffic bottleneck characteristics for a simple and typical expressway on-ramp are investigated by the means of simulation modeling under the open boundary condition. In simulations, the running behaviors of each vehicle are described by a car-following model with a calibrated optimal velocity function, and lane changing actions at the merging section are modeled by a novel set of rules. We numerically derive the traffic volume of on-ramp bottleneck under different upstream arrival rates of mainline and ramp flows. It is found that the vehicles from the ramp strongly affect the pass of mainline vehicles and the merging ratio changes with the increasing of ramp vehicle, when the arrival rate of mainline flow is greater than a critical value. In addition, we clarify the dependence of the merging ratio of on-ramp bottleneck on the probability of lane changing and the length of the merging section, and some corresponding intelligent control strategies are proposed in actual traffic application.

A combined M5P tree and hazard-based duration model for predicting urban freeway traffic accident durations.

PubMed

Lin, Lei; Wang, Qian; Sadek, Adel W

2016-06-01

The duration of freeway traffic accidents duration is an important factor, which affects traffic congestion, environmental pollution, and secondary accidents. Among previous studies, the M5P algorithm has been shown to be an effective tool for predicting incident duration. M5P builds a tree-based model, like the traditional classification and regression tree (CART) method, but with multiple linear regression models as its leaves. The problem with M5P for accident duration prediction, however, is that whereas linear regression assumes that the conditional distribution of accident durations is normally distributed, the distribution for a "time-to-an-event" is almost certainly nonsymmetrical. A hazard-based duration model (HBDM) is a better choice for this kind of a "time-to-event" modeling scenario, and given this, HBDMs have been previously applied to analyze and predict traffic accidents duration. Previous research, however, has not yet applied HBDMs for accident duration prediction, in association with clustering or classification of the dataset to minimize data heterogeneity. The current paper proposes a novel approach for accident duration prediction, which improves on the original M5P tree algorithm through the construction of a M5P-HBDM model, in which the leaves of the M5P tree model are HBDMs instead of linear regression models. Such a model offers the advantage of minimizing data heterogeneity through dataset classification, and avoids the need for the incorrect assumption of normality for traffic accident durations. The proposed model was then tested on two freeway accident datasets. For each dataset, the first 500 records were used to train the following three models: (1) an M5P tree; (2) a HBDM; and (3) the proposed M5P-HBDM, and the remainder of data were used for testing. The results show that the proposed M5P-HBDM managed to identify more significant and meaningful variables than either M5P or HBDMs. Moreover, the M5P-HBDM had the lowest overall mean absolute percentage error (MAPE). Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of driver's age and side of impact on crash severity along urban freeways: a mixed logit approach.

PubMed

Haleem, Kirolos; Gan, Albert

2013-09-01

This study identifies geometric, traffic, environmental, vehicle-related, and driver-related predictors of crash injury severity on urban freeways. The study takes advantage of the mixed logit model's ability to account for unobserved effects that are difficult to quantify and may affect the model estimation, such as the driver's reaction at the time of crash. Crashes of 5 years occurring on 89 urban freeway segments throughout the state of Florida in the United States were used. Examples of severity predictors explored include traffic volume, distance of the crash to the nearest ramp, and detailed driver's age, vehicle types, and sides of impact. To show how the parameter estimates could vary, a binary logit model was compared with the mixed logit model. It was found that the at-fault driver's age, traffic volume, distance of the crash to the nearest ramp, vehicle type, side of impact, and percentage of trucks significantly influence severity on urban freeways. Additionally, young at-fault drivers were associated with a significant severity risk increase relative to other age groups. It was also observed that some variables in the binary logit model yielded illogic estimates due to ignoring the random variation of the estimation. Since the at-fault driver's age and side of impact were significant random parameters in the mixed logit model, an in-depth investigation was performed. It was noticed that back, left, and right impacts had the highest risk among middle-aged drivers, followed by young drivers, very young drivers, and finally, old and very old drivers. To reduce side impacts due to lane changing, two primary strategies can be recommended. The first strategy is to conduct campaigns to convey the hazardous effect of changing lanes at higher speeds. The second is to devise in-vehicle side crash avoidance systems to alert drivers of a potential crash risk. The study provided a promising approach to screening the predictors before fitting the mixed logit model using the random forest technique. Furthermore, potential countermeasures were proposed to reduce the severity of impacts. Copyright © 2013 National Safety Council and Elsevier Ltd. All rights reserved.

Capacity and road user cost analysis of selected freeway work zones in Texas.

DOT National Transportation Integrated Search

2009-09-01

This research was developed to produce usable and meaningful estimates for work zone capacities under a variety of roadway and traffic conditions, work zone configurations, and lane closure scenarios within Texas. Using data collected at eighteen wor...

Mobility and safety impacts of winter storm events in a freeway environment.

DOT National Transportation Integrated Search

2000-02-01

Several factors influence a driver's decision to travel, choice of vehicle speed, and the safety of a particular trip. These factors include, among others, the trip purpose, time of day, traffic volumes, weather and roadway conditions, and the range ...

Evaluation of adjacent AC and CRC pavement lanes : final report.

DOT National Transportation Integrated Search

1995-02-01

On some of Oregon's highways, particularly on the interstate freeways in Eastern Oregon, most of the heavy trucks travel in the outside lane (right lane). With this kind of truck traffic pattern, the right lane experiences significantly higher axle l...

Effect of freeway level of service and driver education on truck driver stress : phase 1.

DOT National Transportation Integrated Search

2012-08-01

This research primarily deals with truck driver stress and its nature, stressors, and their mutual relationship. During the : study, the different demands of driving that are related to roads, vehicle, traffic conditions, driver predisposition to : s...

Assessment of vehicle performance in harsh environments using LSU driving simulator and numerical simulations.

DOT National Transportation Integrated Search

2015-12-01

With the economic booming development of coastal areas, the importance of the traffic planning becomes : obvious not only in a hurricane evacuation but also in the daily transportation. Vehicle performance on the : freeway during harsh environments i...

Guidance for effective use of pylons for lane separation on preferential lanes and freeway ramps.

DOT National Transportation Integrated Search

2013-05-01

Flexible pylons are gaining popularity as traffic channelizing devices in a variety of applications. The : flexible pylons are less rigid (as compared to concrete barriers) enabling easier access for emergency : vehicles and provide more positive con...

Camera positioning and calibration techniques for integrating traffic surveillance video systems with machine-vision vehicle detection devices.

DOT National Transportation Integrated Search

2002-12-01

The Virginia Department of Transportation, like many other transportation agencies, has invested significantly in extensive closed circuit television (CCTV) systems to monitor freeways in urban areas. Although these systems have proven very effective...

Utilization of remote traffic monitoring devices for urban freeway work zone assessment.

DOT National Transportation Integrated Search

2012-01-01

The objective of this project was to promote and facilitate analysis and evaluation of the impacts of road construction activities in Smart : Work Zone Deployment Initiative (SWZDI) states. : The two primary objectives of this project were to assess ...

Air pollution and health risks due to vehicle traffic.

PubMed

Zhang, Kai; Batterman, Stuart

2013-04-15

Traffic congestion increases vehicle emissions and degrades ambient air quality, and recent studies have shown excess morbidity and mortality for drivers, commuters and individuals living near major roadways. Presently, our understanding of the air pollution impacts from congestion on roads is very limited. This study demonstrates an approach to characterize risks of traffic for on- and near-road populations. Simulation modeling was used to estimate on- and near-road NO2 concentrations and health risks for freeway and arterial scenarios attributable to traffic for different traffic volumes during rush hour periods. The modeling used emission factors from two different models (Comprehensive Modal Emissions Model and Motor Vehicle Emissions Factor Model version 6.2), an empirical traffic speed-volume relationship, the California Line Source Dispersion Model, an empirical NO2-NOx relationship, estimated travel time changes during congestion, and concentration-response relationships from the literature, which give emergency doctor visits, hospital admissions and mortality attributed to NO2 exposure. An incremental analysis, which expresses the change in health risks for small increases in traffic volume, showed non-linear effects. For a freeway, "U" shaped trends of incremental risks were predicted for on-road populations, and incremental risks are flat at low traffic volumes for near-road populations. For an arterial road, incremental risks increased sharply for both on- and near-road populations as traffic increased. These patterns result from changes in emission factors, the NO2-NOx relationship, the travel delay for the on-road population, and the extended duration of rush hour for the near-road population. This study suggests that health risks from congestion are potentially significant, and that additional traffic can significantly increase risks, depending on the type of road and other factors. Further, evaluations of risk associated with congestion must consider travel time, the duration of rush-hour, congestion-specific emission estimates, and uncertainties. Copyright © 2013 Elsevier B.V. All rights reserved.

Air pollution and health risks due to vehicle traffic

PubMed Central

Zhang, Kai; Batterman, Stuart

2014-01-01

Traffic congestion increases vehicle emissions and degrades ambient air quality, and recent studies have shown excess morbidity and mortality for drivers, commuters and individuals living near major roadways. Presently, our understanding of the air pollution impacts from congestion on roads is very limited. This study demonstrates an approach to characterize risks of traffic for on- and near-road populations. Simulation modeling was used to estimate on- and near-road NO2 concentrations and health risks for freeway and arterial scenarios attributable to traffic for different traffic volumes during rush hour periods. The modeling used emission factors from two different models (Comprehensive Modal Emissions Model and Motor Vehicle Emissions Factor Model version 6.2), an empirical traffic speed–volume relationship, the California Line Source Dispersion Model, an empirical NO2–NOx relationship, estimated travel time changes during congestion, and concentration–response relationships from the literature, which give emergency doctor visits, hospital admissions and mortality attributed to NO2 exposure. An incremental analysis, which expresses the change in health risks for small increases in traffic volume, showed non-linear effects. For a freeway, “U” shaped trends of incremental risks were predicted for on-road populations, and incremental risks are flat at low traffic volumes for near-road populations. For an arterial road, incremental risks increased sharply for both on- and near-road populations as traffic increased. These patterns result from changes in emission factors, the NO2–NOx relationship, the travel delay for the on-road population, and the extended duration of rush hour for the near-road population. This study suggests that health risks from congestion are potentially significant, and that additional traffic can significantly increase risks, depending on the type of road and other factors. Further, evaluations of risk associated with congestion must consider travel time, the duration of rush-hour, congestion-specific emission estimates, and uncertainties. PMID:23500830

How long will the traffic flow time series keep efficacious to forecast the future?

NASA Astrophysics Data System (ADS)

Yuan, PengCheng; Lin, XuXun

2017-02-01

This paper investigate how long will the historical traffic flow time series keep efficacious to forecast the future. In this frame, we collect the traffic flow time series data with different granularity at first. Then, using the modified rescaled range analysis method, we analyze the long memory property of the traffic flow time series by computing the Hurst exponent. We calculate the long-term memory cycle and test its significance. We also compare it with the maximum Lyapunov exponent method result. Our results show that both of the freeway traffic flow time series and the ground way traffic flow time series demonstrate positively correlated trend (have long-term memory property), both of their memory cycle are about 30 h. We think this study is useful for the short-term or long-term traffic flow prediction and management.

Implementation and testing of the travel time prediction system (TIPS) : final report, May 2001.

DOT National Transportation Integrated Search

2001-05-01

The Travel Time Prediction System (TIPS) is a portable automated system for predicting and displaying travel time for motorists in advance of and through freeway construction work zones, on a real-time basis. It collects real-time traffic flow data u...

Implementation and testing of the travel time prediction system (TIPS) : executive summary, May 2001.

DOT National Transportation Integrated Search

2001-05-01

The Travel Time Prediction System (TIPS) is a portable automated system for predicting and displaying travel time for motorists in advance of and through freeway construction work zones, on a real-time basis. It collects real-time traffic flow data u...

Houston managed lanes case study : the evolution of the Houston HOV system

DOT National Transportation Integrated Search

2003-09-01

A nine-mile contraflow High Occupancy Vehicle (HOV) lane on the I-45 North Freeway in Houston, Texas was implemented as a demonstration project in 1979. This demonstration borrowed an off-peak direction traffic lane for use by buses and vanpools in t...

Intelligent Transportation Systems, The National Architecture, A Framework For Integrated Transportation Into The 21St Century

DOT National Transportation Integrated Search

1985-08-01

The primary objective of this study was to determine if freeway lighting can be reduced or eliminated during nighttime periods when traffic volume is much lower than design capacity without causing significant reductions in the ability of drivers to ...

Highway median impacts on wildlife movement and mortality : state of the practice survey and gap analysis.

DOT National Transportation Integrated Search

2006-10-01

Highway median barriers are used to separate lanes of traffic and enhance motorist safety on freeways and multi-lane interstate highways. : Median barriers of all types have the potential to impede animal movements across highways. Barriers may also ...

Detection of traffic incidents using nonlinear time series analysis

NASA Astrophysics Data System (ADS)

Fragkou, A. D.; Karakasidis, T. E.; Nathanail, E.

2018-06-01

In this study, we present results of the application of nonlinear time series analysis on traffic data for incident detection. More specifically, we analyze daily volume records of Attica Tollway (Greece) collected from sensors located at various locations. The analysis was performed using the Recurrence Plot (RP) and Recurrence Quantification Analysis (RQA) method of the volume data of the lane closest to the median. The results show that it is possible to identify, through the abrupt change of the dynamics of the system revealed by RPs and RQA, the occurrence of incidents on the freeway and differentiate from recurrent traffic congestion. The proposed methodology could be of interest for big data traffic analysis.

Differences in airborne particle and gaseous concentrations in urban air between weekdays and weekends

NASA Astrophysics Data System (ADS)

Morawska, L.; Jayaratne, E. R.; Mengersen, K.; Jamriska, M.; Thomas, S.

Airborne particle number concentrations and size distributions as well as CO and NO x concentrations monitored at a site within the central business district of Brisbane, Australia were correlated with the traffic flow rate on a nearby freeway with the aim of investigating differences between weekday and weekend pollutant characteristics. Observations over a 5-year monitoring period showed that the mean number particle concentration on weekdays was (8.8±0.1)×10 3 cm -3 and on weekends (5.9±0.2)×10 3 cm -3—a difference of 47%. The corresponding mean particle number median diameters during weekdays and weekends were 44.2±0.3 and 50.2±0.2 nm, respectively. The differences in mean particle number concentration and size between weekdays and weekends were found to be statistically significant at confidence levels of over 99%. During a 1-year period of observation, the mean traffic flow rate on the freeway was 14.2×10 4 and 9.6×10 4 vehicles per weekday and weekend day, respectively—a difference of 48%. The mean diurnal variations of the particle number and the gaseous concentrations closely followed the traffic flow rate on both weekdays and weekends (correlation coefficient of 0.86 for particles). The overall conclusion, as to the effect of traffic on concentration levels of pollutant concentration in the vicinity of a major road (about 100 m) carrying traffic of the order of 10 5 vehicles per day, is that about a 50% increase in traffic flow rate results in similar increases of CO and NO x concentrations and a higher increase of about 70% in particle number concentration.

Effects of road construction intensity and operations on rural freeway work zone capacity.

DOT National Transportation Integrated Search

2014-11-01

Capacity is affected by construction type and its intensity on adjacent open traffic lanes. The effect on capacity is a function of : vehicles moving in and out of the closed lanes of the work zone, and the presence of heavy construction vehicles. Co...

Impacts of carpool utilization on the Katy Freeway authorized vehicle lane 12-month after evaluation. Interim report, September 1984-August 1986

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christiansen, D.L.; McCasland, W.R.

1986-08-01

The report documents the data collected in April through June 1986, one year after carpool utilization of the authorized vehicle lane (AVL) was permitted. Comprehensive traffic data, both on the AVL and the freeway, were collected. In addition, surveys of transit users on the AVL, vanpool drivers on the AVL, vanpool passengers on the AVL, carpool drivers on the AVL, carpool passengers on the AVL, and motorists not using the AVL were undertaken. In the report, these data are compared to similar data collected before carpool utilization was permitted to identify the impacts of permitting carpools to use the AVL.

Efficient determination of vehicle emission factors by fuel use category using on-road measurements: downward trends on Los Angeles freight corridor I-710

PubMed Central

Hudda, N.; Fruin, S.; Delfino, R. J.; Sioutas, C.

2013-01-01

To evaluate the success of vehicle emissions regulations, trends in both fleet-wide average emissions as well as high-emitter emissions are needed, but it is challenging to capture the full spread of vehicle emission factors (EFs) with chassis dynamometer or tunnel studies, and remote sensing studies cannot evaluate particulate compounds. We developed an alternative method that links real-time on-road pollutant measurements from a mobile platform with real-time traffic data, and allows efficient calculation of both the average and the spread of EFs for light-duty gasoline-powered vehicles (LDG) and heavy-duty diesel-powered vehicles (HDD). This is the first study in California to report EFs under a full range of real-world driving conditions on multiple freeways. Fleet average LDG EFs were in agreement with most recent studies and an order of magnitude lower than observed HDD EFs. HDD EFs reflected the relatively rapid decreases in diesel emissions that have recently occurred in Los Angeles/California, and on I-710, a primary route used for goods movement and a focus of additional truck fleet turnover incentives, HDD EFs were often lower than on other freeways. When freeway emission rates (ER) were quantified as the product of EF and vehicle miles traveled (VMT) per time per mile of freeway, despite a twoto three-fold difference in HDD fractions between freeways, ERs were found to be generally similar in magnitude. Higher LDG VMT on low HDD fraction freeways largely offset the difference. Therefore, the conventional assumption that free ways with the highest HDD fractions are significantly worse sources of total emissions in Los Angeles may no longer be true. PMID:24244208

Efficient determination of vehicle emission factors by fuel use category using on-road measurements: downward trends on Los Angeles freight corridor I-710.

PubMed

Hudda, N; Fruin, S; Delfino, R J; Sioutas, C

2013-01-11

To evaluate the success of vehicle emissions regulations, trends in both fleet-wide average emissions as well as high-emitter emissions are needed, but it is challenging to capture the full spread of vehicle emission factors (EFs) with chassis dynamometer or tunnel studies, and remote sensing studies cannot evaluate particulate compounds. We developed an alternative method that links real-time on-road pollutant measurements from a mobile platform with real-time traffic data, and allows efficient calculation of both the average and the spread of EFs for light-duty gasoline-powered vehicles (LDG) and heavy-duty diesel-powered vehicles (HDD). This is the first study in California to report EFs under a full range of real-world driving conditions on multiple freeways. Fleet average LDG EFs were in agreement with most recent studies and an order of magnitude lower than observed HDD EFs. HDD EFs reflected the relatively rapid decreases in diesel emissions that have recently occurred in Los Angeles/California, and on I-710, a primary route used for goods movement and a focus of additional truck fleet turnover incentives, HDD EFs were often lower than on other freeways. When freeway emission rates (ER) were quantified as the product of EF and vehicle miles traveled (VMT) per time per mile of freeway, despite a twoto three-fold difference in HDD fractions between freeways, ERs were found to be generally similar in magnitude. Higher LDG VMT on low HDD fraction freeways largely offset the difference. Therefore, the conventional assumption that free ways with the highest HDD fractions are significantly worse sources of total emissions in Los Angeles may no longer be true.

Model Development for Risk Assessment of Driving on Freeway under Rainy Weather Conditions

PubMed Central

Cai, Xiaonan; Wang, Chen; Chen, Shengdi; Lu, Jian

2016-01-01

Rainy weather conditions could result in significantly negative impacts on driving on freeways. However, due to lack of enough historical data and monitoring facilities, many regions are not able to establish reliable risk assessment models to identify such impacts. Given the situation, this paper provides an alternative solution where the procedure of risk assessment is developed based on drivers’ subjective questionnaire and its performance is validated by using actual crash data. First, an ordered logit model was developed, based on questionnaire data collected from Freeway G15 in China, to estimate the relationship between drivers’ perceived risk and factors, including vehicle type, rain intensity, traffic volume, and location. Then, weighted driving risk for different conditions was obtained by the model, and further divided into four levels of early warning (specified by colors) using a rank order cluster analysis. After that, a risk matrix was established to determine which warning color should be disseminated to drivers, given a specific condition. Finally, to validate the proposed procedure, actual crash data from Freeway G15 were compared with the safety prediction based on the risk matrix. The results show that the risk matrix obtained in the study is able to predict driving risk consistent with actual safety implications, under rainy weather conditions. PMID:26894434

Particle concentration and Characteristics near a major freeway with heavy-duty diesel traffic.

PubMed

Ntziachristos, Leonidas; Ning, Zhi; Geller, Michael D; Sioutas, Constantinos

2007-04-01

This study presents the number, surface and volume concentrations, and size distribution of particles next to the 1-710 freeway during February through April 2006. 1-710 has the highest ratio (up to 25%) of heavy-duty diesel vehicles in the Los Angeles highway network. Particle concentration measurements were accompanied by measurements of black carbon, elemental and organic carbon, and gaseous species (CO, CO2). Using the incremental increase of CO2 over the background to calculate the dilution ratio, this study makes it possible to compare particle concentrations measured next to the freeway to concentrations measured in roadway tunnels and in vehicle exhaust. In addition to the effect of the dilution ratio on the measured particle concentrations, multivariate linear regressions showed that light and heavy organic carbon concentrations are positively correlated with the particle volume in the nucleation and accumulation modes, respectively. Solar radiation was also positively correlated with the particle surface concentration and the particle volume in the accumulation (40-638 nm) mode, presumably as a result of secondary particle formation. The methods developed in this study may be used to decouple the effect of sampling position, meteorology, and fleet operation on particle concentrations in the proximity of freeways, roadway tunnels, and in street canyons.

Transforming growth factor- 1 C-509T polymorphism, oxidant stress, and early-onset childhood asthma.

PubMed

Salam, Muhammad T; Gauderman, W James; McConnell, Rob; Lin, Pi-Chu; Gilliland, Frank D

2007-12-15

Transforming growth factor (TGF)-beta1 is involved in airway inflammation and remodeling, two key processes in asthma pathogenesis. Tobacco smoke and traffic emissions induce airway inflammation and modulate TGF-beta1 gene expression. We hypothesized that the effects of functional TGF-beta1 variants on asthma occurrence vary by these exposures. We tested these hypotheses among 3,023 children who participated in the Children's Health Study. Tagging single-nucleotide polymorphisms rs4803457 C>T and C-509T (a functional promoter polymorphism) accounted for 94% of the haplotype diversity of the upstream region. Exposure to maternal smoking in utero was based on smoking by biological mother during pregnancy. Residential distance from nearest freeway was calculated based on residential address at study entry. Children with the -509TT genotype had a 1.8-fold increased risk of early persistent asthma (95% confidence interval [CI], 1.11-2.95). This association varied marginally significantly by in utero exposure to maternal smoking. Compared with children with the -509CC/CT genotype with no in utero exposure to maternal smoking, those with the -509TT genotype with such exposure had a 3.4-fold increased risk of early persistent asthma (95% CI, 1.46-7.80; interaction, P = 0.11). The association between TGF-beta1 C-509T and lifetime asthma varied by residential proximity to freeways (interaction P = 0.02). Children with the -509TT genotype living within 500 m of a freeway had over three-fold increased lifetime asthma risk (95% CI, 1.29-7.44) compared with children with CC/CT genotype living > 1500 m from a freeway. Children with the TGF-beta1 -509TT genotype are at increased risk of asthma when they are exposed to maternal smoking in utero or to traffic-related emissions.

Querying and Extracting Timeline Information from Road Traffic Sensor Data

PubMed Central

Imawan, Ardi; Indikawati, Fitri Indra; Kwon, Joonho; Rao, Praveen

2016-01-01

The escalation of traffic congestion in urban cities has urged many countries to use intelligent transportation system (ITS) centers to collect historical traffic sensor data from multiple heterogeneous sources. By analyzing historical traffic data, we can obtain valuable insights into traffic behavior. Many existing applications have been proposed with limited analysis results because of the inability to cope with several types of analytical queries. In this paper, we propose the QET (querying and extracting timeline information) system—a novel analytical query processing method based on a timeline model for road traffic sensor data. To address query performance, we build a TQ-index (timeline query-index) that exploits spatio-temporal features of timeline modeling. We also propose an intuitive timeline visualization method to display congestion events obtained from specified query parameters. In addition, we demonstrate the benefit of our system through a performance evaluation using a Busan ITS dataset and a Seattle freeway dataset. PMID:27563900

Identifying crash-prone traffic conditions under different weather on freeways.

PubMed

Xu, Chengcheng; Wang, Wei; Liu, Pan

2013-09-01

Understanding the relationships between traffic flow characteristics and crash risk under adverse weather conditions will help highway agencies develop proactive safety management strategies to improve traffic safety in adverse weather conditions. The primary objective is to develop separate crash risk prediction models for different weather conditions. The crash data, weather data, and traffic data used in this study were collected on the I-880N freeway in California in 2008 and 2010. This study considered three different weather conditions: clear weather, rainy weather, and reduced visibility weather. The preliminary analysis showed that there was some heterogeneity in the risk estimates for traffic flow characteristics by weather conditions, and that the crash risk prediction model for all weather conditions cannot capture the impacts of the traffic flow variables on crash risk under adverse weather conditions. The Bayesian random intercept logistic regression models were applied to link the likelihood of crash occurrence with various traffic flow characteristics under different weather conditions. The crash risk prediction models were compared to their corresponding logistic regression model. It was found that the random intercept model improved the goodness-of-fit of the crash risk prediction models. The model estimation results showed that the traffic flow characteristics contributing to crash risk were different across different weather conditions. The speed difference between upstream and downstream stations was found to be significant in each crash risk prediction model. Speed difference between upstream and downstream stations had the largest impact on crash risk in reduced visibility weather, followed by that in rainy weather. The ROC curves were further developed to evaluate the predictive performance of the crash risk prediction models under different weather conditions. The predictive performance of the crash risk model for clear weather was better than those of the crash risk models for adverse weather conditions. The research results could promote a better understanding of the impacts of traffic flow characteristics on crash risk under adverse weather conditions, which will help transportation professionals to develop better crash prevention strategies in adverse weather. Copyright © 2013 National Safety Council and Elsevier Ltd. All rights reserved.

Continuum modeling of cooperative traffic flow dynamics

NASA Astrophysics Data System (ADS)

Ngoduy, D.; Hoogendoorn, S. P.; Liu, R.

2009-07-01

This paper presents a continuum approach to model the dynamics of cooperative traffic flow. The cooperation is defined in our model in a way that the equipped vehicle can issue and receive a warning massage when there is downstream congestion. Upon receiving the warning massage, the (up-stream) equipped vehicle will adapt the current desired speed to the speed at the congested area in order to avoid sharp deceleration when approaching the congestion. To model the dynamics of such cooperative systems, a multi-class gas-kinetic theory is extended to capture the adaptation of the desired speed of the equipped vehicle to the speed at the downstream congested traffic. Numerical simulations are carried out to show the influence of the penetration rate of the equipped vehicles on traffic flow stability and capacity in a freeway.

I-35w incident management and impact of incidents on freeway operations. Final report, 1976-1979

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lari, A.; Christianson, D.; Porter, S.

1982-01-01

I-35W and I-94 Traffic Management System have been in operation since 1974. As of December 1979, the TMS operation included six principal functional subsystems. These are (1) a 24 camera closed circuit television network (2) 38 ramp meter signals, (3) eleven express bus and/or carpool meter bypass ramps, (4) a motorist information program including changeable message signs, lane control signals, highway advisory radio and a traffic grade information sign, (5) the Traffic Management Center and (6) an incident detection and response program. The purpose of this study was twofold: first, available incident records accumulated on the TMS were analyzed tomore » develop a comprehensive view of the types and quantities of incidents that have occurred. Second, the incident data base and companion volume and occupancy data was used to determine the impact of 'typical' incidents and the impact of the total incident problem. Included in the report is an analysis of incident types detected, mode of incident detection, duration of incidents, and incident response activities.« less

Dynamic Centralized and Decentralized Control Systems

DOT National Transportation Integrated Search

1977-09-01

This report develops a systematic method for designing suboptimal decentralized control systems. The method is then applied to the design of a decentralized controller for a freeway-corridor system. A freeway corridor is considered to be a system of ...

Optimized Structure of the Traffic Flow Forecasting Model With a Deep Learning Approach.

PubMed

Yang, Hao-Fan; Dillon, Tharam S; Chen, Yi-Ping Phoebe

2017-10-01

Forecasting accuracy is an important issue for successful intelligent traffic management, especially in the domain of traffic efficiency and congestion reduction. The dawning of the big data era brings opportunities to greatly improve prediction accuracy. In this paper, we propose a novel model, stacked autoencoder Levenberg-Marquardt model, which is a type of deep architecture of neural network approach aiming to improve forecasting accuracy. The proposed model is designed using the Taguchi method to develop an optimized structure and to learn traffic flow features through layer-by-layer feature granulation with a greedy layerwise unsupervised learning algorithm. It is applied to real-world data collected from the M6 freeway in the U.K. and is compared with three existing traffic predictors. To the best of our knowledge, this is the first time that an optimized structure of the traffic flow forecasting model with a deep learning approach is presented. The evaluation results demonstrate that the proposed model with an optimized structure has superior performance in traffic flow forecasting.

Demonstration of alternative traffic information collection and management technologies

NASA Astrophysics Data System (ADS)

Knee, Helmut E.; Smith, Cy; Black, George; Petrolino, Joe

2004-03-01

Many of the components associated with the deployment of Intelligent Transportation Systems (ITS) to support a traffic management center (TMC) such as remote control cameras, traffic speed detectors, and variable message signs, have been available for many years. Their deployment, however, has been expensive and applied primarily to freeways and interstates, and have been deployed principally in the major metropolitan areas in the US; not smaller cities. The Knoxville (Tennessee) Transportation Planning Organization is sponsoring a project that will test the integration of several technologies to estimate near-real time traffic information data and information that could eventually be used by travelers to make better and more informed decisions related to their travel needs. The uniqueness of this demonstration is that it will seek to predict traffic conditions based on cellular phone signals already being collected by cellular communications companies. Information about the average speed on various portions of local arterials and incident identification (incident location) will be collected and compared to similar data generated by "probe vehicles". Successful validation of the speed information generated from cell phone data will allow traffic data to be generated much more economically and utilize technologies that are minimally infrastructure invasive. Furthermore, when validated, traffic information could be provided to the traveling public allowing then to make better decisions about trips. More efficient trip planning and execution can reduce congestion and associated vehicle emissions. This paper will discuss the technologies, the demonstration project, the project details, and future directions.

Applied Distributed Model Predictive Control for Energy Efficient Buildings and Ramp Metering

NASA Astrophysics Data System (ADS)

Koehler, Sarah Muraoka

Industrial large-scale control problems present an interesting algorithmic design challenge. A number of controllers must cooperate in real-time on a network of embedded hardware with limited computing power in order to maximize system efficiency while respecting constraints and despite communication delays. Model predictive control (MPC) can automatically synthesize a centralized controller which optimizes an objective function subject to a system model, constraints, and predictions of disturbance. Unfortunately, the computations required by model predictive controllers for large-scale systems often limit its industrial implementation only to medium-scale slow processes. Distributed model predictive control (DMPC) enters the picture as a way to decentralize a large-scale model predictive control problem. The main idea of DMPC is to split the computations required by the MPC problem amongst distributed processors that can compute in parallel and communicate iteratively to find a solution. Some popularly proposed solutions are distributed optimization algorithms such as dual decomposition and the alternating direction method of multipliers (ADMM). However, these algorithms ignore two practical challenges: substantial communication delays present in control systems and also problem non-convexity. This thesis presents two novel and practically effective DMPC algorithms. The first DMPC algorithm is based on a primal-dual active-set method which achieves fast convergence, making it suitable for large-scale control applications which have a large communication delay across its communication network. In particular, this algorithm is suited for MPC problems with a quadratic cost, linear dynamics, forecasted demand, and box constraints. We measure the performance of this algorithm and show that it significantly outperforms both dual decomposition and ADMM in the presence of communication delay. The second DMPC algorithm is based on an inexact interior point method which is suited for nonlinear optimization problems. The parallel computation of the algorithm exploits iterative linear algebra methods for the main linear algebra computations in the algorithm. We show that the splitting of the algorithm is flexible and can thus be applied to various distributed platform configurations. The two proposed algorithms are applied to two main energy and transportation control problems. The first application is energy efficient building control. Buildings represent 40% of energy consumption in the United States. Thus, it is significant to improve the energy efficiency of buildings. The goal is to minimize energy consumption subject to the physics of the building (e.g. heat transfer laws), the constraints of the actuators as well as the desired operating constraints (thermal comfort of the occupants), and heat load on the system. In this thesis, we describe the control systems of forced air building systems in practice. We discuss the "Trim and Respond" algorithm which is a distributed control algorithm that is used in practice, and show that it performs similarly to a one-step explicit DMPC algorithm. Then, we apply the novel distributed primal-dual active-set method and provide extensive numerical results for the building MPC problem. The second main application is the control of ramp metering signals to optimize traffic flow through a freeway system. This application is particularly important since urban congestion has more than doubled in the past few decades. The ramp metering problem is to maximize freeway throughput subject to freeway dynamics (derived from mass conservation), actuation constraints, freeway capacity constraints, and predicted traffic demand. In this thesis, we develop a hybrid model predictive controller for ramp metering that is guaranteed to be persistently feasible and stable. This contrasts to previous work on MPC for ramp metering where such guarantees are absent. We apply a smoothing method to the hybrid model predictive controller and apply the inexact interior point method to this nonlinear non-convex ramp metering problem.

A kinematic wave model in Lagrangian coordinates incorporating capacity drop: Application to homogeneous road stretches and discontinuities

NASA Astrophysics Data System (ADS)

Yuan, Kai; Knoop, Victor L.; Hoogendoorn, Serge P.

2017-01-01

On freeways, congestion always leads to capacity drop. This means the queue discharge rate is lower than the pre-queue capacity. Our recent research findings indicate that the queue discharge rate increases with the speed in congestion, that is the capacity drop is strongly correlated with the congestion state. Incorporating this varying capacity drop into a kinematic wave model is essential for assessing consequences of control strategies. However, to the best of authors' knowledge, no such a model exists. This paper fills the research gap by presenting a Lagrangian kinematic wave model. "Lagrangian" denotes that the new model is solved in Lagrangian coordinates. The new model can give capacity drops accompanying both of stop-and-go waves (on homogeneous freeway section) and standing queues (at nodes) in a network. The new model can be applied in a network operation. In this Lagrangian kinematic wave model, the queue discharge rate (or the capacity drop) is a function of vehicular speed in traffic jams. Four case studies on links as well as at lane-drop and on-ramp nodes show that the Lagrangian kinematic wave model can give capacity drops well, consistent with empirical observations.

Effect of traffic and driving characteristics on morphology of atmospheric soot particles at freeway on-ramps.

PubMed

China, Swarup; Salvadori, Neila; Mazzoleni, Claudio

2014-03-18

Vehicles represent a major source of soot in urban environments. Knowledge of the morphology and mixing of soot particles is fundamental to understand their potential health and climatic impacts. We investigate 5738 single particles collected at six different cloverleaf freeway on-ramps in Southern Michigan, using 2D images from scanning electron microscopy. Of those, 3364 particles are soot. We present an analysis of the morphological and mixing properties of those soot particles. The relative abundance of soot particles shows a positive association with traffic density (number of vehicles per minute). A classification of the mixing state of freshly emitted soot particles shows that most of them are bare (or thinly coated) (72%) and some are partly coated (22%). We find that the fractal dimension of soot particles (one of the most relevant morphological descriptors) varies from site to site, and increases with increasing vehicle specific power that represents the driving/engine load conditions, and with increasing percentage of vehicles older than 15 years. Our results suggest that driving conditions, and vehicle age and type have significant influence on the morphology of soot particles.

Longitudinal safety evaluation of electric vehicles with the partial wireless charging lane on freeways.

PubMed

Li, Ye; Wang, Wei; Xing, Lu; Fan, Qi; Wang, Hao

2018-02-01

As an environment friendly transportation mode, the electric vehicle (EV) has drawn an increasing amount of attention from governments, vehicle manufactories and researchers recently. One of the biggest issue impeding EV's popularization associates with the charging process. The wireless charging lane (WCL) has been proposed as a convenient charging facility for EVs. Due to the high costs, the application of WCL on the entire freeways is impractical in the near future, while the partial WCL (PWCL) may be a feasible solution. This study aims to evaluate longitudinal safety of EVs with PWCL on freeways based on simulations. The simulation experiments are firstly designed, including deployment of PWCL on freeways and distribution of state of charge (SOC) of EVs. Then, a vehicle behavior model for EVs is proposed based on the intelligent driver model (IDM). Two surrogate safety measures, derived from time-to-collision (TTC), are utilized as indicators for safety evaluations. Sensitivity analysis is also conducted for related factors. Results show that the distribution of EVs' SOC significantly affect longitudinal safety when the PWCL is utilized. The low SOC in traffic consisting of EVs has the negative effect on longitudinal safety. The randomness and incompliance of EV drivers worsens the safety performance. The sensitivity analysis indicates that the larger maximum deceleration rate results in the higher longitudinal crash risks of EVs, while the length of PWCL has no monotonous effect. Different TTC thresholds also show no impact on results. A case study shows the consistent results. Based on the findings, several suggestions are discussed for EVs' safety improvement. Results of this study provide useful information for freeway safety when EVs are applied in the future. Copyright © 2017 Elsevier Ltd. All rights reserved.

Field evaluation of vegetation and noise barriers for mitigation of near-freeway air pollution under variable wind conditions

NASA Astrophysics Data System (ADS)

Lee, Eon S.; Ranasinghe, Dilhara R.; Ahangar, Faraz Enayati; Amini, Seyedmorteza; Mara, Steven; Choi, Wonsik; Paulson, Suzanne; Zhu, Yifang

2018-02-01

Traffic-related air pollutants are a significant public health concern, particularly near freeways. Previous studies have suggested either soundwall or vegetation barriers might reduce the near-freeway air pollution. This study aims to investigate the effectiveness of a combination of both soundwall and vegetation barrier for reducing ultrafine particles (UFPs, diameter ≤ 100 nm) and PM2.5 (diameter ≤ 2.5 μm) concentrations. Concurrent data collection was carried out at both upwind and downwind fixed locations approximately 10-15 m away from the edge of two major freeways in California. This study observed that the reduction of UFP and PM2.5 was generally greater with the combination barrier than with either soundwall or vegetation alone. Since there were no non-barrier sites at the study locations, the reductions reported here are all in relative terms. The soundwall barrier was more effective for reducing PM2.5 (25-53%) than UFPs (0-5%), and was most effective (51-53% for PM2.5) when the wind speed ranged between 1 and 2 m/s. Under the same range of wind speed, the vegetation barrier had little effect (0-5%) on reducing PM2.5; but was effective at reducing UFP (up to 50%). For both types of roadside barrier, decreasing wind speed resulted in greater net reduction of UFPs (i.e., total number particle concentrations; inversely proportional). This trend was observed, however, only within specific particle size ranges (i.e., diameter < 20 nm for the soundwall barrier and 12-60 nm for the vegetation barrier). Out of these size ranges, the reduction of UFP concentration was proportional to increasing wind speed. Overall findings of this study support positive effects of soundwall and vegetation barriers for near-freeway air pollution mitigation.

City traffic flow breakdown prediction based on fuzzy rough set

NASA Astrophysics Data System (ADS)

Yang, Xu; Da-wei, Hu; Bing, Su; Duo-jia, Zhang

2017-05-01

In city traffic management, traffic breakdown is a very important issue, which is defined as a speed drop of a certain amount within a dense traffic situation. In order to predict city traffic flow breakdown accurately, in this paper, we propose a novel city traffic flow breakdown prediction algorithm based on fuzzy rough set. Firstly, we illustrate the city traffic flow breakdown problem, in which three definitions are given, that is, 1) Pre-breakdown flow rate, 2) Rate, density, and speed of the traffic flow breakdown, and 3) Duration of the traffic flow breakdown. Moreover, we define a hazard function to represent the probability of the breakdown ending at a given time point. Secondly, as there are many redundant and irrelevant attributes in city flow breakdown prediction, we propose an attribute reduction algorithm using the fuzzy rough set. Thirdly, we discuss how to predict the city traffic flow breakdown based on attribute reduction and SVM classifier. Finally, experiments are conducted by collecting data from I-405 Freeway, which is located at Irvine, California. Experimental results demonstrate that the proposed algorithm is able to achieve lower average error rate of city traffic flow breakdown prediction.

Ambient ultrafine particles provide a strong adjuvant effect in the secondary immune response: implication for traffic-related asthma flares

PubMed Central

Li, Ning; Harkema, Jack R.; Lewandowski, Ryan P.; Wang, Meiying; Bramble, Lori A.; Gookin, Glenn R.; Ning, Zhi; Kleinman, Michael T.; Sioutas, Constantinos

2010-01-01

We have previously demonstrated that intranasal administration of ambient ultrafine particles (UFP) acts as an adjuvant for primary allergic sensitization to ovalbumin (OVA) in Balb/c mice. It is important to find out whether inhaled UFP exert the same effect on the secondary immune response as a way of explaining asthma flares in already-sensitized individuals due to traffic exposure near a freeway. The objective of this study is to determine whether inhalation exposure to ambient UFP near an urban freeway could enhance the secondary immune response to OVA in already-sensitized mice. Prior OVA-sensitized animals were exposed to concentrated ambient UFP at the time of secondary OVA challenge in our mobile animal laboratory in Los Angeles. OVA-specific antibody production, airway morphometry, allergic airway inflammation, cytokine gene expression, and oxidative stress marker were assessed. As few as five ambient UFP exposures were sufficient to promote the OVA recall immune response, including generating allergic airway inflammation in smaller and more distal airways compared with the adjuvant effect of intranasally instilled UFP on the primary immune response. The secondary immune response was characterized by the T helper 2 and IL-17 cytokine gene expression in the lung. In summary, our results demonstrated that inhalation of prooxidative ambient UFP could effectively boost the secondary immune response to an experimental allergen, indicating that vehicular traffic exposure could exacerbate allergic inflammation in already-sensitized subjects. PMID:20562226

Seven Experiment Designs Addressing Problems of Safety and Capacity on Two-Lane Rural Highways : Volume 8. Experimental Design and Evaluate Remedial Aids for Intersections with Inadequate Sight Distance

DOT National Transportation Integrated Search

2007-01-01

Americans lose 3.7 billion hours and 2.3 billion gallons of fuel every year sitting in traffic jams, and nearly 24 percent of non-recurring freeway delay, or about 482 million hours, is attributed to work zones. To combat the country's growing transp...

2Loud?: Community mapping of exposure to traffic noise with mobile phones.

PubMed

Leao, Simone; Ong, Kok-Leong; Krezel, Adam

2014-10-01

Despite ample medical evidence of the adverse impacts of traffic noise on health, most policies for traffic noise management are arbitrary or incomplete, resulting in serious social and economic impacts. Surprisingly, there is limited information about citizen's exposure to traffic noise worldwide. This paper presents the 2Loud? mobile phone application, developed and tested as a methodology to monitor, assess and map the level of exposure to traffic noise of citizens with focus on the night period and indoor locations, since sleep disturbance is one of the major triggers for ill health related to traffic noise. Based on a community participation experiment using the 2Loud? mobile phone application in a region close to freeways in Australia, the results of this research indicates a good level of accuracy for the noise monitoring by mobile phones and also demonstrates significant levels of indoor night exposure to traffic noise in the study area. The proposed methodology, through the data produced and the participatory process involved, can potentially assist in planning and management towards healthier urban environments.

Health, Traffic, and Environmental Justice: Collaborative Research and Community Action in San Francisco, California

PubMed Central

Sciammas, Charlie; Seto, Edmund; Bhatia, Rajiv; Rivard, Tom

2009-01-01

Health impacts on neighborhood residents from transportation systems can be an environmental justice issue. To assess the effects of transportation planning decisions, including the construction of an intraurban freeway, on residents of the Excelsior neighborhood in southeast San Francisco, PODER (People Organizing to Demand Environmental and Economic Rights), a local grassroots environmental justice organization; the San Francisco Department of Public Health; and the University of California, Berkeley, collaborated on participatory research. We used our findings regarding traffic-related exposures and health hazards in the area to facilitate community education and action to address transportation-related health burdens on neighborhood residents. PMID:19890147

Use of the Box and Jenkins time series technique in traffic forecasting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nihan, N.L.; Holmesland, K.O.

The use of recently developed time series techniques for short-term traffic volume forecasting is examined. A data set containing monthly volumes on a freeway segment for 1968-76 is used to fit a time series model. The resultant model is used to forecast volumes for 1977. The forecast volumes are then compared with actual volumes in 1977. Time series techniques can be used to develop highly accurate and inexpensive short-term forecasts. The feasibility of using these models to evaluate the effects of policy changes or other outside impacts is considered. (1 diagram, 1 map, 14 references,2 tables)

Symmetry breaking in optimal timing of traffic signals on an idealized two-way street.

PubMed

Panaggio, Mark J; Ottino-Löffler, Bertand J; Hu, Peiguang; Abrams, Daniel M

2013-09-01

Simple physical models based on fluid mechanics have long been used to understand the flow of vehicular traffic on freeways; analytically tractable models of flow on an urban grid, however, have not been as extensively explored. In an ideal world, traffic signals would be timed such that consecutive lights turned green just as vehicles arrived, eliminating the need to stop at each block. Unfortunately, this "green-wave" scenario is generally unworkable due to frustration imposed by competing demands of traffic moving in different directions. Until now this has typically been resolved by numerical simulation and optimization. Here, we develop a theory for the flow in an idealized system consisting of a long two-way road with periodic intersections. We show that optimal signal timing can be understood analytically and that there are counterintuitive asymmetric solutions to this signal coordination problem. We further explore how these theoretical solutions degrade as traffic conditions vary and automotive density increases.

Symmetry breaking in optimal timing of traffic signals on an idealized two-way street

NASA Astrophysics Data System (ADS)

Panaggio, Mark J.; Ottino-Löffler, Bertand J.; Hu, Peiguang; Abrams, Daniel M.

2013-09-01

Simple physical models based on fluid mechanics have long been used to understand the flow of vehicular traffic on freeways; analytically tractable models of flow on an urban grid, however, have not been as extensively explored. In an ideal world, traffic signals would be timed such that consecutive lights turned green just as vehicles arrived, eliminating the need to stop at each block. Unfortunately, this “green-wave” scenario is generally unworkable due to frustration imposed by competing demands of traffic moving in different directions. Until now this has typically been resolved by numerical simulation and optimization. Here, we develop a theory for the flow in an idealized system consisting of a long two-way road with periodic intersections. We show that optimal signal timing can be understood analytically and that there are counterintuitive asymmetric solutions to this signal coordination problem. We further explore how these theoretical solutions degrade as traffic conditions vary and automotive density increases.

Real-world emission factors for antimony and other brake wear related trace elements: size-segregated values for light and heavy duty vehicles.

PubMed

Bukowiecki, Nicolas; Lienemann, Peter; Hill, Matthias; Figi, Renato; Richard, Agnes; Furger, Markus; Rickers, Karen; Falkenberg, Gerald; Zhao, Yongjing; Cliff, Steven S; Prevot, Andre S H; Baltensperger, Urs; Buchmann, Brigitte; Gehrig, Robert

2009-11-01

Hourly trace element measurements were performed in an urban street canyon and next to an interurban freeway in Switzerland during more than one month each, deploying a rotating drum impactor (RDI) and subsequent sample analysis by synchrotron radiation X-ray fluorescence spectrometry (SR-XRF). Antimony and other brake wear associated elements were detected in three particle size ranges (2.5-10, 1-2.5, and 0.1-1 microm). The hourly measurements revealed that the effect of resuspended road dust has to be taken into account for the calculation of vehicle emission factors. Individual values for light and heavy duty vehicles were obtained for stop-and-go traffic in the urban street canyon. Mass based brake wear emissions were predominantly found in the coarse particle fraction. For antimony, determined emission factors were 11 +/- 7 and 86 +/- 42 microg km(-1) vehicle(-1) for light and heavy duty vehicles, respectively. Antimony emissions along the interurban freeway with free-flowing traffic were significantly lower. Relative patterns for brake wear related elements were very similar for both considered locations. Beside vehicle type specific brake wear emissions, road dust resuspension was found to be a dominant contributor of antimony in the street canyon.

Investigating the impact of static roadside advertising on drivers' situation awareness.

PubMed

Young, Kristie L; Stephens, Amanda N; Logan, David B; Lenné, Michael G

2017-04-01

Roadside advertising has the potential to create a crash risk for drivers as it may distract attention from driving at critical times. In an on-road instrumented vehicle study, we examined if and how static advertising billboards affect drivers' situation awareness across different driving environments. Nineteen fully licensed drivers drove an instrumented vehicle around a 38 km urban test route comprising freeway, busy urban retail and arterial road sections. The route contained a number of static billboards. Drivers provided continuous verbal protocols throughout the drive. Results indicated that the structure and content of drivers' situation awareness was not appreciably affected by the billboards in any of the road environments examined. Drivers focused their attention on the billboards when driving demand was low, such as when driving on the freeway with light to moderate traffic, in lower speed zones, or when stationary. However, when drivers were required to perform a manoeuvre or driving demands increased, drivers directed less attention to the billboards and focussed their awareness on the immediate driving task. This suggests that drivers can, at least under some conditions, effectively self-regulate their attention to billboards when required to focus on the immediate traffic or driving situation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modeling of dispersion near roadways based on the vehicle-induced turbulence concept

NASA Astrophysics Data System (ADS)

Sahlodin, Ali M.; Sotudeh-Gharebagh, Rahmat; Zhu, Yifang

A mathematical model is developed for dispersion near roadways by incorporating vehicle-induced turbulence (VIT) into Gaussian dispersion modeling using computational fluid dynamics (CFD). The model is based on the Gaussian plume equation in which roadway is regarded as a series of point sources. The Gaussian dispersion parameters are modified by simulation of the roadway using CFD in order to evaluate turbulent kinetic energy (TKE) as a measure of VIT. The model was evaluated against experimental carbon monoxide concentrations downwind of two major freeways reported in the literature. Good agreements were achieved between model results and the literature data. A significant difference was observed between the model results with and without considering VIT. The difference is rather high for data very close to the freeways. This model, after evaluation with additional data, may be used as a framework for predicting dispersion and deposition from any roadway for different traffic (vehicle type and speed) conditions.

Analyzing crash frequency in freeway tunnels: A correlated random parameters approach.

PubMed

Hou, Qinzhong; Tarko, Andrew P; Meng, Xianghai

2018-02-01

The majority of past road safety studies focused on open road segments while only a few focused on tunnels. Moreover, the past tunnel studies produced some inconsistent results about the safety effects of the traffic patterns, the tunnel design, and the pavement conditions. The effects of these conditions therefore remain unknown, especially for freeway tunnels in China. The study presented in this paper investigated the safety effects of these various factors utilizing a four-year period (2009-2012) of data as well as three models: 1) a random effects negative binomial model (RENB), 2) an uncorrelated random parameters negative binomial model (URPNB), and 3) a correlated random parameters negative binomial model (CRPNB). Of these three, the results showed that the CRPNB model provided better goodness-of-fit and offered more insights into the factors that contribute to tunnel safety. The CRPNB was not only able to allocate the part of the otherwise unobserved heterogeneity to the individual model parameters but also was able to estimate the cross-correlations between these parameters. Furthermore, the study results showed that traffic volume, tunnel length, proportion of heavy trucks, curvature, and pavement rutting were associated with higher frequencies of traffic crashes, while the distance to the tunnel wall, distance to the adjacent tunnel, distress ratio, International Roughness Index (IRI), and friction coefficient were associated with lower crash frequencies. In addition, the effects of the heterogeneity of the proportion of heavy trucks, the curvature, the rutting depth, and the friction coefficient were identified and their inter-correlations were analyzed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of the Scottsdale Loop 101 automated speed enforcement demonstration program.

PubMed

Shin, Kangwon; Washington, Simon P; van Schalkwyk, Ida

2009-05-01

Speeding is recognized as a major contributing factor in traffic crashes. In order to reduce speed-related crashes, the city of Scottsdale, Arizona implemented the first fixed-camera photo speed enforcement program (SEP) on a limited access freeway in the US. The 9-month demonstration program spanning from January 2006 to October 2006 was implemented on a 6.5 mile urban freeway segment of Arizona State Route 101 running through Scottsdale. This paper presents the results of a comprehensive analysis of the impact of the SEP on speeding behavior, crashes, and the economic impact of crashes. The impact on speeding behavior was estimated using generalized least square estimation, in which the observed speeds and the speeding frequencies during the program period were compared to those during other periods. The impact of the SEP on crashes was estimated using 3 evaluation methods: a before-and-after (BA) analysis using a comparison group, a BA analysis with traffic flow correction, and an empirical Bayes BA analysis with time-variant safety. The analysis results reveal that speeding detection frequencies (speeds> or =76 mph) increased by a factor of 10.5 after the SEP was (temporarily) terminated. Average speeds in the enforcement zone were reduced by about 9 mph when the SEP was implemented, after accounting for the influence of traffic flow. All crash types were reduced except rear-end crashes, although the estimated magnitude of impact varies across estimation methods (and their corresponding assumptions). When considering Arizona-specific crash related injury costs, the SEP is estimated to yield about $17 million in annual safety benefits.

Using naturalistic driving study data to investigate the impact of driver distraction on driver's brake reaction time in freeway rear-end events in car-following situation.

PubMed

Gao, Jingru; Davis, Gary A

2017-12-01

The rear-end crash is one of the most common freeway crash types, and driver distraction is often cited as a leading cause of rear-end crashes. Previous research indicates that driver distraction could have negative effects on driving performance, but the specific association between driver distraction and crash risk is still not fully revealed. This study sought to understand the mechanism by which driver distraction, defined as secondary task distraction, could influence crash risk, as indicated by a driver's reaction time, in freeway car-following situations. A statistical analysis, exploring the causal model structure regarding drivers' distraction impacts on reaction times, was conducted. Distraction duration, distraction scenario, and secondary task type were chosen as distraction-related factors. Besides, exogenous factors including weather, visual obstruction, lighting condition, traffic density, and intersection presence and endogenous factors including driver age and gender were considered. There was an association between driver distraction and reaction time in the sample freeway rear-end events from SHRP 2 NDS database. Distraction duration, the distracted status when a leader braked, and secondary task type were related to reaction time, while all other factors showed no significant effect on reaction time. The analysis showed that driver distraction duration is the primary direct cause of the increase in reaction time, with other factors having indirect effects mediated by distraction duration. Longer distraction duration, the distracted status when a leader braked, and engaging in auditory-visual-manual secondary task tended to result in longer reaction times. Given drivers will be distracted occasionally, countermeasures which shorten distraction duration or avoid distraction presence while a leader vehicle brakes are worth considering. This study helps better understand the mechanism of freeway rear-end events in car-following situations, and provides a methodology that can be adopted to study the association between driver behavior and driving features. Copyright © 2017 National Safety Council and Elsevier Ltd. All rights reserved.

Effect of adaptive cruise control systems on mixed traffic flow near an on-ramp

NASA Astrophysics Data System (ADS)

Davis, L. C.

2007-06-01

Mixed traffic flow consisting of vehicles equipped with adaptive cruise control (ACC) and manually driven vehicles is analyzed using car-following simulations. Simulations of merging from an on-ramp onto a freeway reported in the literature have not thus far demonstrated a substantial positive impact of ACC. In this paper cooperative merging for ACC vehicles is proposed to improve throughput and increase distance traveled in a fixed time. In such a system an ACC vehicle senses not only the preceding vehicle in the same lane but also the vehicle immediately in front in the other lane. Prior to reaching the merge region, the ACC vehicle adjusts its velocity to ensure that a safe gap for merging is obtained. If on-ramp demand is moderate, cooperative merging produces significant improvement in throughput (20%) and increases up to 3.6 km in distance traveled in 600 s for 50% ACC mixed flow relative to the flow of all-manual vehicles. For large demand, it is shown that autonomous merging with cooperation in the flow of all ACC vehicles leads to throughput limited only by the downstream capacity, which is determined by speed limit and headway time.

Understanding widely scattered traffic flows, the capacity drop, and platoons as effects of variance-driven time gaps

NASA Astrophysics Data System (ADS)

Treiber, Martin; Kesting, Arne; Helbing, Dirk

2006-07-01

We investigate the adaptation of the time headways in car-following models as a function of the local velocity variance, which is a measure of the inhomogeneity of traffic flow. We apply this mechanism to several car-following models and simulate traffic breakdowns in open systems with an on-ramp as bottleneck and in a closed ring road. Single-vehicle data and one-minute aggregated data generated by several virtual detectors show a semiquantitative agreement with microscopic and flow-density data from the Dutch freeway A9. This includes the observed distributions of the net time headways for free and congested traffic, the velocity variance as a function of density, and the fundamental diagram. The modal value of the time headway distribution is shifted by a factor of about 2 under congested conditions. Macroscopically, this corresponds to the capacity drop at the transition from free to congested traffic. The simulated fundamental diagram shows free, synchronized, and jammed traffic, and a wide scattering in the congested traffic regime. We explain this by a self-organized variance-driven process that leads to the spontaneous formation and decay of long-lived platoons even for a deterministic dynamics on a single lane.

Developing an area-wide system for coordinated ramp meter control.

DOT National Transportation Integrated Search

2008-12-01

Ramp metering has been broadly accepted and deployed as an effective countermeasure : against both recurrent and non-recurrent congestion on freeways. However, many current ramp : metering algorithms tend to improve only freeway travels using local d...

Self-organized criticality in asymmetric exclusion model with noise for freeway traffic

NASA Astrophysics Data System (ADS)

Nagatani, Takashi

1995-02-01

The one-dimensional asymmetric simple-exclusion model with open boundaries for parallel update is extended to take into account temporary stopping of particles. The model presents the traffic flow on a highway with temporary deceleration of cars. Introducing temporary stopping into the asymmetric simple-exclusion model drives the system asymptotically into a steady state exhibiting a self-organized criticality. In the self-organized critical state, start-stop waves (or traffic jams) appear with various sizes (or lifetimes). The typical interval < s>between consecutive jams scales as < s> ≃ Lv with v = 0.51 ± 0.05 where L is the system size. It is shown that the cumulative jam-interval distribution Ns( L) satisfies the finite-size scaling form ( Ns( L) ≃ L- vf( s/ Lv). Also, the typical lifetime ≃ Lv‧ with v‧ = 0.52 ± 0.05. The cumulative distribution Nm( L) of lifetimes satisfies the finite-size scaling form Nm( L)≃ L-1g( m/ Lv‧).

Building a Multivariable Linear Regression Model of On-road Traffic for Creation of High Resolution Emission Inventories

NASA Astrophysics Data System (ADS)

Powell, James Eckhardt

Emissions inventories are an important tool, often built by governments, and used to manage emissions. To build an inventory of urban CO2 emissions and other fossil fuel combustion products in the urban atmosphere, an inventory of on-road traffic is required. In particular, a high resolution inventory is necessary to capture the local characteristics of transport emissions. These emissions vary widely due to the local nature of the fleet, fuel, and roads. Here we show a new model of ADT for the Portland, OR metropolitan region. The backbone is traffic counter recordings made by the Portland Bureau of Transportation at 7,767 sites over 21 years (1986-2006), augmented with PORTAL (The Portland Regional Transportation Archive Listing) freeway traffic count data. We constructed a regression model to fill in traffic network gaps using GIS data such as road class and population density. An EPA-supplied emissions factor was used to estimate transportation CO2 emissions, which is compared to several other estimates for the city's CO2 footprint.

Congested traffic states in empirical observations and microscopic simulations

NASA Astrophysics Data System (ADS)

Treiber, Martin; Hennecke, Ansgar; Helbing, Dirk

2000-08-01

We present data from several German freeways showing different kinds of congested traffic forming near road inhomogeneities, specifically lane closings, intersections, or uphill gradients. The states are localized or extended, homogeneous or oscillating. Combined states are observed as well, like the coexistence of moving localized clusters and clusters pinned at road inhomogeneities, or regions of oscillating congested traffic upstream of nearly homogeneous congested traffic. The experimental findings are consistent with a recently proposed theoretical phase diagram for traffic near on-ramps [D. Helbing, A. Hennecke, and M. Treiber, Phys. Rev. Lett. 82, 4360 (1999)]. We simulate these situations with a continuous microscopic single-lane model, the ``intelligent driver model,'' using empirical boundary conditions. All observations, including the coexistence of states, are qualitatively reproduced by describing inhomogeneities with local variations of one model parameter. We show that the results of the microscopic model can be understood by formulating the theoretical phase diagram for bottlenecks in a more general way. In particular, a local drop of the road capacity induced by parameter variations has essentially the same effect as an on-ramp.

Age and pedestrian injury severity in motor-vehicle crashes: a heteroskedastic logit analysis.

PubMed

Kim, Joon-Ki; Ulfarsson, Gudmundur F; Shankar, Venkataraman N; Kim, Sungyop

2008-09-01

This research explores the injury severity of pedestrians in motor-vehicle crashes. It is hypothesized that the variance of unobserved pedestrian characteristics increases with age. In response, a heteroskedastic generalized extreme value model is used. The analysis links explanatory factors with four injury outcomes: fatal, incapacitating, non-incapacitating, and possible or no injury. Police-reported crash data between 1997 and 2000 from North Carolina, USA, are used. The results show that pedestrian age induces heteroskedasticity which affects the probability of fatal injury. The effect grows more pronounced with increasing age past 65. The heteroskedastic model provides a better fit than the multinomial logit model. Notable factors increasing the probability of fatal pedestrian injury: increasing pedestrian age, male driver, intoxicated driver (2.7 times greater probability of fatality), traffic sign, commercial area, darkness with or without streetlights (2-4 times greater probability of fatality), sport-utility vehicle, truck, freeway, two-way divided roadway, speeding-involved, off roadway, motorist turning or backing, both driver and pedestrian at fault, and pedestrian only at fault. Conversely, the probability of a fatal injury decreased: with increasing driver age, during the PM traffic peak, with traffic signal control, in inclement weather, on a curved roadway, at a crosswalk, and when walking along roadway.

U.S. National Interests in the Asia-Pacific Region

DTIC Science & Technology

1991-04-22

ADDRESS (City, State, and ZIP Code) 10 SOURCE OF FUNDING NUMBERS PROGRAM PROJECT TASK WORK UNIT ELEMENT NO. NO. NO. ACCESSION %0 11. TITLE (Include...through the work of missionaries while the Asian countries would produce "bolts of cloth", his vision that the traffic would be a two- way affair has...critical freeway which links a number of countries with extreme diversity in history, culture , and economic development. This diversity ranges from an

Development and application of traffic flow information collecting and analysis system based on multi-type video

NASA Astrophysics Data System (ADS)

Lu, Mujie; Shang, Wenjie; Ji, Xinkai; Hua, Mingzhuang; Cheng, Kuo

2015-12-01

Nowadays, intelligent transportation system (ITS) has already become the new direction of transportation development. Traffic data, as a fundamental part of intelligent transportation system, is having a more and more crucial status. In recent years, video observation technology has been widely used in the field of traffic information collecting. Traffic flow information contained in video data has many advantages which is comprehensive and can be stored for a long time, but there are still many problems, such as low precision and high cost in the process of collecting information. This paper aiming at these problems, proposes a kind of traffic target detection method with broad applicability. Based on three different ways of getting video data, such as aerial photography, fixed camera and handheld camera, we develop a kind of intelligent analysis software which can be used to extract the macroscopic, microscopic traffic flow information in the video, and the information can be used for traffic analysis and transportation planning. For road intersections, the system uses frame difference method to extract traffic information, for freeway sections, the system uses optical flow method to track the vehicles. The system was applied in Nanjing, Jiangsu province, and the application shows that the system for extracting different types of traffic flow information has a high accuracy, it can meet the needs of traffic engineering observations and has a good application prospect.

Teaching artificial neural systems to drive: Manual training techniques for autonomous systems

NASA Technical Reports Server (NTRS)

Shepanski, J. F.; Macy, S. A.

1987-01-01

A methodology was developed for manually training autonomous control systems based on artificial neural systems (ANS). In applications where the rule set governing an expert's decisions is difficult to formulate, ANS can be used to extract rules by associating the information an expert receives with the actions taken. Properly constructed networks imitate rules of behavior that permits them to function autonomously when they are trained on the spanning set of possible situations. This training can be provided manually, either under the direct supervision of a system trainer, or indirectly using a background mode where the networks assimilates training data as the expert performs its day-to-day tasks. To demonstrate these methods, an ANS network was trained to drive a vehicle through simulated freeway traffic.

Safety performance of traffic phases and phase transitions in three phase traffic theory.

PubMed

Xu, Chengcheng; Liu, Pan; Wang, Wei; Li, Zhibin

2015-12-01

Crash risk prediction models were developed to link safety to various phases and phase transitions defined by the three phase traffic theory. Results of the Bayesian conditional logit analysis showed that different traffic states differed distinctly with respect to safety performance. The random-parameter logit approach was utilized to account for the heterogeneity caused by unobserved factors. The Bayesian inference approach based on the Markov Chain Monte Carlo (MCMC) method was used for the estimation of the random-parameter logit model. The proposed approach increased the prediction performance of the crash risk models as compared with the conventional logit model. The three phase traffic theory can help us better understand the mechanism of crash occurrences in various traffic states. The contributing factors to crash likelihood can be well explained by the mechanism of phase transitions. We further discovered that the free flow state can be divided into two sub-phases on the basis of safety performance, including a true free flow state in which the interactions between vehicles are minor, and a platooned traffic state in which bunched vehicles travel in successions. The results of this study suggest that a safety perspective can be added to the three phase traffic theory. The results also suggest that the heterogeneity between different traffic states should be considered when estimating the risks of crash occurrences on freeways. Copyright © 2015 Elsevier Ltd. All rights reserved.

Exposure to traffic-related air pollution during pregnancy and term low birth weight: estimation of causal associations in a semiparametric model.

PubMed

Padula, Amy M; Mortimer, Kathleen; Hubbard, Alan; Lurmann, Frederick; Jerrett, Michael; Tager, Ira B

2012-11-01

Traffic-related air pollution is recognized as an important contributor to health problems. Epidemiologic analyses suggest that prenatal exposure to traffic-related air pollutants may be associated with adverse birth outcomes; however, there is insufficient evidence to conclude that the relation is causal. The Study of Air Pollution, Genetics and Early Life Events comprises all births to women living in 4 counties in California's San Joaquin Valley during the years 2000-2006. The probability of low birth weight among full-term infants in the population was estimated using machine learning and targeted maximum likelihood estimation for each quartile of traffic exposure during pregnancy. If everyone lived near high-volume freeways (approximated as the fourth quartile of traffic density), the estimated probability of term low birth weight would be 2.27% (95% confidence interval: 2.16, 2.38) as compared with 2.02% (95% confidence interval: 1.90, 2.12) if everyone lived near smaller local roads (first quartile of traffic density). Assessment of potentially causal associations, in the absence of arbitrary model assumptions applied to the data, should result in relatively unbiased estimates. The current results support findings from previous studies that prenatal exposure to traffic-related air pollution may adversely affect birth weight among full-term infants.

Structure of the San Bernardino Basin Along Two Seismic Transects: Rialto-Colton Fault to the San Andreas Fault and Along the I-215 Freeway (I-10 to SR30)

USGS Publications Warehouse

Catchings, R.D.; Rymer, M.J.; Goldman, M.R.; Gandhok, G.; Steedman, C.E.

2008-01-01

In this report, we present seismic data and acquisition parameters for two seismic profiles acquired in the San Bernardino, California area in May and October 2003. We refer to these seismic profiles as the San Bernardino Regional (SBR) and San Bernardino High-Resolution (SBHR) seismic profiles. We present both un-interpreted and interpreted seismic images so that the structure of the area can independently interpreted by others. We explain the rationale for our interpretations within the text of this report, and in addition, we provide a large body of supporting evidence. The SBR seismic profile extended across the San Bernardino Basin approximately N30?E from the town of Colton to the town of Highland. The data were acquired at night when the signal-to-noise ratios were reasonably good, and for the larger shots, seismic energy propagated across the ~20-km-long array. Tomographic velocity data are available to depths of about 4 km, and low-fold reflection data are available to depths in excess of 5 km. The SBR seismic data reveal an asymmetric, fault-bound basin to about 5 km depth. The SBHR seismic profile trended along the I-215 freeway from its intersection with the Santa Ana River to approximately State Road 30 in San Bernardino. Seismic data acquired along the I-215 freeway provide detailed images, with CDP spacing of approximately 2.5 m along an approximately 8.2-km-long profile; shot and geophone spacing was 5 m. For logistical reasons, the high-resolution (SBHR) seismic data were acquired during daylight hours on the shoulder of the I-215 freeway and within 5 to 10 m of high-traffic volumes, resulting in low signal-to-noise ratios. The limited offset at which refracted first-arrivals could be measured along the SBHR seismic profile limited our measurements of tomographic refraction velocities to relatively shallow (< 150 m) depths. The SBHR reflection data reveal a basin with complex structural details within the upper kilometer. The two seismic profiles show internal consistency and consistency with other existing geophysical data. Collectively, the data suggest that the I-215 freeway trends along the faulted edge of a pull-apart basin, within a zone where the principal slip of the San Jacinto Fault is transferred to the San Andreas Fault. Because the I-215 freeway trends at low angles to these flower-structure faults, both primary and numerous secondary faults are apparent between the I-10 exchange and State Road-30, suggesting that much of the 8-km-long segment of the I-215 freeway could experience movement along primary or secondary faults.

Visual ergonomic evaluations on four different designs of LED traffic signs

NASA Astrophysics Data System (ADS)

Chen, Yi-Chun; Huang, Ting-Yuan; Lee, Tsung-Xian; Sun, Ching-Cherng

2017-08-01

To investigate the legibility and visual comfort of LED traffic signs, an ergonomic experiment is performed on four custom-designed LED traffic signs, including three self-luminous ones as LED lightbox, LED backlight and regional LED backlight, and one non-self-luminous sign with external LED lighting. The four signs are hanged side-by-side and evaluated by observers through questionnaires. The signage dimension is one-sixth of the real freeway traffic signs, and the observation distance is 25 m. The luminance of three self-luminous signs is 216 cd/m2. The illuminance of external LED lighting is 400 lux on the traffic sign. The ambient illuminance is 2.8 and 6.0 lux in two rounds. The results show that self-luminous traffic signs provide superior legibility, visual comfort and user preference than the non-self-luminous one. Among the three self-luminous signs, regional LED backlight is most susceptible to the ambient illumination. LED lightbox has significantly better preference score than LED backlight under darker ambient lighting. Only LED lightbox has significantly better visual comfort than external LED lighting in the brighter environment. Based on the four LED traffic signs evaluated in this study, we suggest LED lightbox as the prior choice. Further investigations on the effect of ambient illumination and other designs of self-luminous traffic signs are in progress.

Visibility and spacing of lane control signals for freeway traffic management. Interim research report, September 1993-September 1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ullman, G.L.; Tallamraju, S.S.; Trout, N.D.

1994-11-01

Glance legibility studies conducted at the TTI Proving Grounds examined the legibility of three commercially available LCS with respect to symbol, signal type, subject gender, and subject age. Also, the effect of ambient light conditions was also explored. Symbols on all three signals resulted in median glance legibility distances of 304.8 meters (1000 feet) or greater, whereas the 85th percentile glance legibility distance was 213.4 meters (700 feet) or greater. Of the various factors examined, only the age of the subject significantly influenced legibility distances. In general, drivers 65 years and older had to be 91.5 to 198.1 meters (300more » to 650 feet) closer to the signals to correctly identify the symbols being displayed than drivers aged 16 to 44 years.« less

A Bayesian network based framework for real-time crash prediction on the basic freeway segments of urban expressways.

PubMed

Hossain, Moinul; Muromachi, Yasunori

2012-03-01

The concept of measuring the crash risk for a very short time window in near future is gaining more practicality due to the recent advancements in the fields of information systems and traffic sensor technology. Although some real-time crash prediction models have already been proposed, they are still primitive in nature and require substantial improvements to be implemented in real-life. This manuscript investigates the major shortcomings of the existing models and offers solutions to overcome them with an improved framework and modeling method. It employs random multinomial logit model to identify the most important predictors as well as the most suitable detector locations to acquire data to build such a model. Afterwards, it applies Bayesian belief net (BBN) to build the real-time crash prediction model. The model has been constructed using high resolution detector data collected from Shibuya 3 and Shinjuku 4 expressways under the jurisdiction of Tokyo Metropolitan Expressway Company Limited, Japan. It has been specifically built for the basic freeway segments and it predicts the chance of formation of a hazardous traffic condition within the next 4-9 min for a particular 250 meter long road section. The performance evaluation results reflect that at an average threshold value the model is able to successful classify 66% of the future crashes with a false alarm rate less than 20%. Copyright © 2011 Elsevier Ltd. All rights reserved.

Drivers’ Visual Search Patterns during Overtaking Maneuvers on Freeway

PubMed Central

Zhang, Wenhui; Dai, Jing; Pei, Yulong; Li, Penghui; Yan, Ying; Chen, Xinqiang

2016-01-01

Drivers gather traffic information primarily by means of their vision. Especially during complicated maneuvers, such as overtaking, they need to perceive a variety of characteristics including the lateral and longitudinal distances with other vehicles, the speed of others vehicles, lane occupancy, and so on, to avoid crashes. The primary object of this study is to examine the appropriate visual search patterns during overtaking maneuvers on freeways. We designed a series of driving simulating experiments in which the type and speed of the leading vehicle were considered as two influential factors. One hundred and forty participants took part in the study. The participants overtook the leading vehicles just like they would usually do so, and their eye movements were collected by use of the Eye Tracker. The results show that participants’ gaze durations and saccade durations followed normal distribution patterns and that saccade angles followed a log-normal distribution pattern. It was observed that the type of leading vehicle significantly impacted the drivers’ gaze duration and gaze frequency. As the speed of a leading vehicle increased, subjects’ saccade durations became longer and saccade angles became larger. In addition, the initial and destination lanes were found to be key areas with the highest visual allocating proportion, accounting for more than 65% of total visual allocation. Subjects tended to more frequently shift their viewpoints between the initial lane and destination lane in order to search for crucial traffic information. However, they seldom directly shifted their viewpoints between the two wing mirrors. PMID:27869764

NOx emissions from Euro IV busses with SCR systems associated with urban, suburban and freeway driving patterns.

PubMed

Fu, Mingliang; Ge, Yunshan; Wang, Xin; Tan, Jianwei; Yu, Linxiao; Liang, Bin

2013-05-01

NOx and particulate matter (PM) emissions from heavy-duty diesel vehicles (HDVs) have become the most important sources of pollutants affecting urban air quality in China. In recent years, a series of emission control strategies and diesel engine polices have been introduced that require advanced emission control technology. China and Europe mostly have used Selective Catalytic Reduction (SCR) with urea to meet the Euro IV diesel engine emission standard. In this study, two Euro IV busses with SCR were tested by using potable emission measurement system (PEMS) to assess NOx emissions associated with urban, suburban and freeway driving patterns. The results indicated that with the SCR system, the urea injection time for the entire driving period increased with higher vehicle speed. For freeway driving, the urea injection time covered 71%-83% of the driving period; the NOx emission factors from freeway driving were lower than those associated with urban and suburban driving. Unfortunately, the NOx emission factors were 2.6-2.8-, 2.3-2.7- and 2.2-2.3-fold higher than the Euro IV standard limits for urban, suburban and freeway driving, respectively; NOx emission factors (in g/km and g/(kW·h)) from the original vehicles (without SCR) were higher than their corresponding vehicles with SCR for suburban and freeway driving. Compared with the IVE model results, the measured NOx emission factors were 1.60-1.16-, 1.77-1.27-, 2.49-2.44-fold higher than the NOx predicted by the IVE model for urban and suburban driving, respectively. Thus, an adjustment of emission factors is needed to improve the estimation of Euro IV vehicle emissions in China. Copyright © 2013 Elsevier B.V. All rights reserved.

The impact of vehicle moving violations and freeway traffic flow on crash risk: An application of plugin development for microsimulation.

PubMed

Wang, Junhua; Kong, Yumeng; Fu, Ting; Stipancic, Joshua

2017-01-01

This paper presents the use of the Aimsun microsimulation program to simulate vehicle violating behaviors and observe their impact on road traffic crash risk. Plugins for violations of speeding, slow driving, and abrupt stopping were developed using Aimsun's API and SDK module. A safety analysis plugin for investigating probability of rear-end collisions was developed, and a method for analyzing collision risk is proposed. A Fuzzy C-mean Clustering algorithm was developed to identify high risk states in different road segments over time. Results of a simulation experiment based on the G15 Expressway in Shanghai showed that abrupt stopping had the greatest impact on increasing collision risk, and the impact of violations increased with traffic volume. The methodology allows for the evaluation and monitoring of risks, alerting of road hazards, and identification of hotspots, and could be applied to the operations of existing facilities or planning of future ones.

The impact of vehicle moving violations and freeway traffic flow on crash risk: An application of plugin development for microsimulation

PubMed Central

Kong, Yumeng; Stipancic, Joshua

2017-01-01

This paper presents the use of the Aimsun microsimulation program to simulate vehicle violating behaviors and observe their impact on road traffic crash risk. Plugins for violations of speeding, slow driving, and abrupt stopping were developed using Aimsun’s API and SDK module. A safety analysis plugin for investigating probability of rear-end collisions was developed, and a method for analyzing collision risk is proposed. A Fuzzy C-mean Clustering algorithm was developed to identify high risk states in different road segments over time. Results of a simulation experiment based on the G15 Expressway in Shanghai showed that abrupt stopping had the greatest impact on increasing collision risk, and the impact of violations increased with traffic volume. The methodology allows for the evaluation and monitoring of risks, alerting of road hazards, and identification of hotspots, and could be applied to the operations of existing facilities or planning of future ones. PMID:28886141

Correlation of ambient pollution levels and heavily-trafficked roadway proximity on the prevalence of smear-positive tuberculosis.

PubMed

Jassal, M S; Bakman, I; Jones, B

2013-03-01

Varying levels of evidence exist for the contribution of indoor air pollution and environmental tobacco smoke as a risk factor for tuberculosis (TB). Despite a similar mechanism of action, the influence of outdoor air pollution exposure as an independent contributor to TB disease has yet to be explored. This area of inquiry is of increasing importance given the level of pollution in the rising economies of many TB-endemic nations. Los Angeles' unique physical environs and traffic patterns mirror other global megacities with a greater burden of TB therefore allowing for preliminary correlative studies. This preliminary study hypothesizes that individuals who reside proximal to elevated pollutant exposures are likely to have a greater burden of disease--as evidenced by sputum smear-positive TB. Retrospective medical records review. Medical records of non-homeless individuals (n = 196) diagnosed with culture positive TB at Los Angeles County and University of Southern California Medical Center Hospital were analyzed from January 2007 to December 2008. The study population was grouped according to acid-fast bacilli (AFB) smear-positive (n = 111) and smear-negative (n = 85) status. Air pollutant exposure was captured using measurements of ozone (O3) and particulate matter with an aerodynamic diameter of less than 2.5 (PM2.5). Individual assignment to O3 and PM2.5 exposures were based on residential proximity to the nearest US Environmental Protection Agency's monitoring station. Proximity of home residences to traffic-related pollutants occurred by measurement of distance to the nearest freeway and major non-freeway road. Single factorial models yielded a significant correlation of smear-positive status and residential exposure to PM2.5. Residential distance to freeways and major arterial roads did not yield an association. This is the first report linking ambient pollution exposure as a risk factor for TB. PM2.5 may have the potential to impact TB lung pathology as evidenced by the linkage of fine particulate matter levels and smear-positive TB. Copyright © 2013 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Exposure to Traffic-related Air Pollution During Pregnancy and Term Low Birth Weight: Estimation of Causal Associations in a Semiparametric Model

PubMed Central

Padula, Amy M.; Mortimer, Kathleen; Hubbard, Alan; Lurmann, Frederick; Jerrett, Michael; Tager, Ira B.

2012-01-01

Traffic-related air pollution is recognized as an important contributor to health problems. Epidemiologic analyses suggest that prenatal exposure to traffic-related air pollutants may be associated with adverse birth outcomes; however, there is insufficient evidence to conclude that the relation is causal. The Study of Air Pollution, Genetics and Early Life Events comprises all births to women living in 4 counties in California's San Joaquin Valley during the years 2000–2006. The probability of low birth weight among full-term infants in the population was estimated using machine learning and targeted maximum likelihood estimation for each quartile of traffic exposure during pregnancy. If everyone lived near high-volume freeways (approximated as the fourth quartile of traffic density), the estimated probability of term low birth weight would be 2.27% (95% confidence interval: 2.16, 2.38) as compared with 2.02% (95% confidence interval: 1.90, 2.12) if everyone lived near smaller local roads (first quartile of traffic density). Assessment of potentially causal associations, in the absence of arbitrary model assumptions applied to the data, should result in relatively unbiased estimates. The current results support findings from previous studies that prenatal exposure to traffic-related air pollution may adversely affect birth weight among full-term infants. PMID:23045474

Sensor Location Problem Optimization for Traffic Network with Different Spatial Distributions of Traffic Information.

PubMed

Bao, Xu; Li, Haijian; Qin, Lingqiao; Xu, Dongwei; Ran, Bin; Rong, Jian

2016-10-27

To obtain adequate traffic information, the density of traffic sensors should be sufficiently high to cover the entire transportation network. However, deploying sensors densely over the entire network may not be realistic for practical applications due to the budgetary constraints of traffic management agencies. This paper describes several possible spatial distributions of traffic information credibility and proposes corresponding different sensor information credibility functions to describe these spatial distribution properties. A maximum benefit model and its simplified model are proposed to solve the traffic sensor location problem. The relationships between the benefit and the number of sensors are formulated with different sensor information credibility functions. Next, expanding models and algorithms in analytic results are performed. For each case, the maximum benefit, the optimal number and spacing of sensors are obtained and the analytic formulations of the optimal sensor locations are derived as well. Finally, a numerical example is proposed to verify the validity and availability of the proposed models for solving a network sensor location problem. The results show that the optimal number of sensors of segments with different model parameters in an entire freeway network can be calculated. Besides, it can also be concluded that the optimal sensor spacing is independent of end restrictions but dependent on the values of model parameters that represent the physical conditions of sensors and roads.

Sensor Location Problem Optimization for Traffic Network with Different Spatial Distributions of Traffic Information

PubMed Central

Bao, Xu; Li, Haijian; Qin, Lingqiao; Xu, Dongwei; Ran, Bin; Rong, Jian

2016-01-01

To obtain adequate traffic information, the density of traffic sensors should be sufficiently high to cover the entire transportation network. However, deploying sensors densely over the entire network may not be realistic for practical applications due to the budgetary constraints of traffic management agencies. This paper describes several possible spatial distributions of traffic information credibility and proposes corresponding different sensor information credibility functions to describe these spatial distribution properties. A maximum benefit model and its simplified model are proposed to solve the traffic sensor location problem. The relationships between the benefit and the number of sensors are formulated with different sensor information credibility functions. Next, expanding models and algorithms in analytic results are performed. For each case, the maximum benefit, the optimal number and spacing of sensors are obtained and the analytic formulations of the optimal sensor locations are derived as well. Finally, a numerical example is proposed to verify the validity and availability of the proposed models for solving a network sensor location problem. The results show that the optimal number of sensors of segments with different model parameters in an entire freeway network can be calculated. Besides, it can also be concluded that the optimal sensor spacing is independent of end restrictions but dependent on the values of model parameters that represent the physical conditions of sensors and roads. PMID:27801794

No more freeways : urban land use-transportation dynamics without freeway capacity expansion

DOT National Transportation Integrated Search

2011-01-01

Observations of the various limitations of freeway capacity expansion have led to a provocative planning and policy question What if we : completely stop building additional freeway capacity. From a theoretical perspective, as a freeway transport...

Prenatal Exposure to Urban Air Nanoparticles in Mice Causes Altered Neuronal Differentiation and Depression-Like Responses

PubMed Central

Godar, Sean C.; Sander, Thomas K.; Iwata, Nahoko; Pakbin, Payam; Shih, Jean C.; Berhane, Kiros; McConnell, Rob; Sioutas, Constantinos

2013-01-01

Emerging evidence suggests that excessive exposure to traffic-derived air pollution during pregnancy may increase the vulnerability to neurodevelopmental alterations that underlie a broad array of neuropsychiatric disorders. We present a mouse model for prenatal exposure to urban freeway nanoparticulate matter (nPM). In prior studies, we developed a model for adult rodent exposure to re-aerosolized urban nPM which caused inflammatory brain responses with altered neuronal glutamatergic functions. nPMs are collected continuously for one month from a local freeway and stored as an aqueous suspension, prior to re-aerosolization for exposure of mice under controlled dose and duration. This paradigm was used for a pilot study of prenatal nPM impact on neonatal neurons and adult behaviors. Adult C57BL/6J female mice were exposed to re-aerosolized nPM (350 µg/m3) or control filtered ambient air for 10 weeks (3×5 hour exposures per week), encompassing gestation and oocyte maturation prior to mating. Prenatal nPM did not alter litter size, pup weight, or postnatal growth. Neonatal cerebral cortex neurons at 24 hours in vitro showed impaired differentiation, with 50% reduction of stage 3 neurons with long neurites and correspondingly more undifferentiated neurons at Stages 0 and 1. Neuron number after 24 hours of culture was not altered by prenatal nPM exposure. Addition of exogenous nPM (2 µg/ml) to the cultures impaired pyramidal neuron Stage 3 differentiation by 60%. Adult males showed increased depression-like responses in the tail-suspension test, but not anxiety-related behaviors. These pilot data suggest that prenatal exposure to nPM can alter neuronal differentiation with gender-specific behavioral sequelae that may be relevant to human prenatal exposure to urban vehicular aerosols. PMID:23734187

The Physics of Traffic

NASA Astrophysics Data System (ADS)

Davis, L. Craig

2006-03-01

Congestion in freeway traffic is an example of self-organization in the language of complexity theory. Nonequilibrium, first-order phase transitions from free flow cause complex spatiotemporal patterns. Two distinct phases of congestion are observed in empirical traffic data--wide moving jams and synchronous flow. Wide moving jams are characterized by stopped or slowly moving vehicles within the jammed region, which widens and moves upstream at 15-20 km/h. Above a critical density of vehicles, a sudden decrease in the velocity of a lead vehicle can initiate a transition from metastable states to this phase. Human behaviors, especially delayed reactions, are implicated in the formation of jams. The synchronous flow phase results from a bottleneck such as an on-ramp. Thus, in contrast to a jam, the downstream front is pinned at a fixed location. The name of the phase comes from the equilibration (or synchronization) of speed and flow rate across all lanes caused by frequent vehicle lane changes. Synchronous flow occurs when the mainline flow and the rate of merging from an on-ramp are sufficiently large. Large-scale simulations using car-following models reproduce the physical phenomena occurring in traffic and suggest methods to improve flow and mediate congestion.

Measurements of ultrafine particles carrying different number of charges in on- and near-freeway environments

NASA Astrophysics Data System (ADS)

Lee, Eon S.; Xu, Bin; Zhu, Yifang

2012-12-01

This paper presents measurements of electrical charges on ultrafine particles (UFPs) of different electrical mobility diameters (30, 50, 80, and 100 nm) in on- and near-freeway environments. Using a tandem Differential Mobility Analyzer (DMA) system, we first examined the fraction of UFPs carrying different number of charges on two distinctive freeways: a gasoline-vehicle dominated freeway (I-405) and a heavy-duty diesel truck dominated freeway (I-710). The fractions of UFPs of a given size carrying one or more charges were significantly higher on the freeways than in the background. The background UFPs only carried up to two charges but freeway UFPs could have up to three charges. The total fraction of charged particles was higher on the I-710 than I-405 across the studied electrical mobility diameters. Near the I-405 freeway, we observed a strong decay of charged particles on the downwind side of the freeway. We also found fractional decay of the charged particles was faster than total particle number concentrations, but slower than total ion concentrations downwind from the freeway I-405. Among charged particles, the highest decay rate was observed for particles carrying three charges. Near the I-710 freeway, we found strong net positive charges on nucleation mode particles, suggesting that UFPs were not at steady-state charge equilibrium near freeways.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobson, L.N.

Traffic congestion and personal mobility preservation are the most challenging issues facing transportation professionals. From Phoenix to San Francisco to Washington, D.C., citizens are identifying transportation as their number one concern, outweighing issues such as pollution, overpopulation, unemployment, and crime. In the state of Washington, particularly in the greater Seattle area, congestion is likewise a major concern. In order to address the mobility problems facing the urban areas of Washington, the state initiated a new transportation research and implementation program in October 1987. The program is called Freeway and Arterial Management Effort (FAME). The focus of the program is discussedmore » by the author.« less

COST-BENEFIT Analysis in Railway Noise Control

NASA Astrophysics Data System (ADS)

OERTLI, J.

2000-03-01

A method to calculate the network-wide costs of realizing different noise control possibilities and their benefits in terms of noise reduction for lineside inhabitants has been implemented in Switzerland. These studies have shown that an optimal cost distribution consists of spending 65% of the available finances on rolling stock improvement, 30% on noise control barriers and 5% on insulated windows. This mix protects 70% of the lineside population for 30% of the cost necessary to attain threshold levels for all inhabitants. This noise control strategy has been accepted by the federal traffic and environment agencies involved and will save billions of Swiss francs. The success of the calculation methodology has prompted development of a Europe-wide decision support system to the same effect. Along two freight freeways the relationship between rolling stock improvement, noise barriers, insulated windows, operational measures and track characteristics is being studied. The decision support system will allow determination of those combinations with the best cost-benefit ratios. The study is currently being undertaken as a joint venture by the railways of Switzerland, France, Germany and the Netherlands as well as the European Rail Research Institute. The results constitute part of the negotiating strategy of the railways with European and national legislators.

Prediction and analysis of near-road concentrations using a reduced-form emission/dispersion model

PubMed Central

2010-01-01

Background Near-road exposures of traffic-related air pollutants have been receiving increased attention due to evidence linking emissions from high-traffic roadways to adverse health outcomes. To date, most epidemiological and risk analyses have utilized simple but crude exposure indicators, most typically proximity measures, such as the distance between freeways and residences, to represent air quality impacts from traffic. This paper derives and analyzes a simplified microscale simulation model designed to predict short- (hourly) to long-term (annual average) pollutant concentrations near roads. Sensitivity analyses and case studies are used to highlight issues in predicting near-road exposures. Methods Process-based simulation models using a computationally efficient reduced-form response surface structure and a minimum number of inputs integrate the major determinants of air pollution exposures: traffic volume and vehicle emissions, meteorology, and receptor location. We identify the most influential variables and then derive a set of multiplicative submodels that match predictions from "parent" models MOBILE6.2 and CALINE4. The assembled model is applied to two case studies in the Detroit, Michigan area. The first predicts carbon monoxide (CO) concentrations at a monitoring site near a freeway. The second predicts CO and PM2.5 concentrations in a dense receptor grid over a 1 km2 area around the intersection of two major roads. We analyze the spatial and temporal patterns of pollutant concentration predictions. Results Predicted CO concentrations showed reasonable agreement with annual average and 24-hour measurements, e.g., 59% of the 24-hr predictions were within a factor of two of observations in the warmer months when CO emissions are more consistent. The highest concentrations of both CO and PM2.5 were predicted to occur near intersections and downwind of major roads during periods of unfavorable meteorology (e.g., low wind speeds) and high emissions (e.g., weekday rush hour). The spatial and temporal variation among predicted concentrations was significant, and resulted in unusual distributional and correlation characteristics, including strong negative correlation for receptors on opposite sides of a road and the highest short-term concentrations on the "upwind" side of the road. Conclusions The case study findings can likely be generalized to many other locations, and they have important implications for epidemiological and other studies. The reduced-form model is intended for exposure assessment, risk assessment, epidemiological, geographical information systems, and other applications. PMID:20579353

Truck monitoring and warning systems for freeway-to-freeway connections

DOT National Transportation Integrated Search

1999-10-01

This research focuses on the development and evaluation of a truck monitoring and warning (TM&W) system for detecting high, long, fast trucks at freeway-to-freeway connections and activating displays to warn the truck drivers of potential hazards as ...

Driver performance and attention allocation in use of logo signs on freeway exit ramps.

PubMed

Zahabi, Maryam; Machado, Patricia; Lau, Mei Ying; Deng, Yulin; Pankok, Carl; Hummer, Joseph; Rasdorf, William; Kaber, David B

2017-11-01

The objective of this research was to quantify the effects of driver age, ramp signage configuration, including number of panels, logo format and sign familiarity, on driver performance and attention allocation when exiting freeways. Sixty drivers participated in a simulator study and analysis of variance models were used to assess response effects of the controlled manipulations. Results revealed elderly drivers to demonstrate worse performance and conservative control strategies as compared to middle-aged and young drivers. Elderly drivers also exhibited lower off-road fixation frequency and shorter off-road glance durations compared to middle-aged and young drivers. In general, drivers adopted a more conservative strategy when exposed to nine-panel signs as compared to six-panel signs and were more accurate in target detection when searching six-panels vs. nine and with familiar vs. unfamiliar logos. These findings provide an applicable guide for agency design of freeway ramp signage accounting for driver demographics. Copyright © 2017 Elsevier Ltd. All rights reserved.

Truck monitoring and warning systems for freeway-to-freeway connections : summary

DOT National Transportation Integrated Search

1999-10-01

This project focuses on the development and evaluation of a truck monitoring and warning (TM&W) system for detecting high, long, fast trucks at freeway-to-freeway connections and activating displays to warn the truck drivers of potential hazards as t...

On-road emission factors of PM pollutants for light-duty vehicles (LDVs) based on urban street driving conditions

NASA Astrophysics Data System (ADS)

Kam, Winnie; Liacos, James W.; Schauer, James J.; Delfino, Ralph J.; Sioutas, Constantinos

2012-12-01

An on-road sampling campaign was conducted on two major surface streets (Wilshire and Sunset Boulevards) in Los Angeles, CA, to characterize PM components including metals, trace elements, and organic species for three PM size fractions (PM10-2.5, PM2.5-0.25, and PM0.25). Fuel-based emission factors (mass of pollutant per kg of fuel) were calculated to assess the emissions profile of a light-duty vehicle (LDV) traffic fleet characterized by stop-and-go driving conditions that are reflective of urban street driving. Emission factors for metals and trace elements were highest in PM10-2.5 while emission factors for PAHs and hopanes and steranes were highest in PM0.25. PM2.5 emission factors were also compared to previous freeway, roadway tunnel, and dynamometer studies based on an LDV fleet to determine how various environments and driving conditions may influence concentrations of PM components. The on-road sampling methodology deployed in the current study captured substantially higher levels of metals and trace elements associated with vehicular abrasion (Fe, Ca, Cu, and Ba) and crustal origins (Mg and Al) than previous LDV studies. The semi-volatile nature of PAHs resulted in higher levels of PAHs in the particulate phase for LDV tunnel studies (Phuleria et al., 2006) and lower levels of PAHs in the particulate phase for freeway studies (Ning et al., 2008). With the exception of a few high molecular weight PAHs, the current study's emission factors were in between the LDV tunnel and LDV freeway studies. In contrast, hopane and sterane emission factors were generally comparable between the current study, the LDV tunnel, and LDV freeway, as expected given the greater atmospheric stability of these organic compounds. Overall, the emission factors from the dynamometer studies for metals, trace elements, and organic species are lower than the current study. Lastly, n-alkanes (C19-C40) were quantified and alkane carbon preference indices (CPIs) were determined to be in the range of 1-2, indicating substantial anthropogenic source contribution for surface streets in Los Angeles.

Temporal and spatial variation in allocating annual traffic activity across an urban region and implications for air quality assessments

PubMed Central

Batterman, Stuart

2015-01-01

Patterns of traffic activity, including changes in the volume and speed of vehicles, vary over time and across urban areas and can substantially affect vehicle emissions of air pollutants. Time-resolved activity at the street scale typically is derived using temporal allocation factors (TAFs) that allow the development of emissions inventories needed to predict concentrations of traffic-related air pollutants. This study examines the spatial and temporal variation of TAFs, and characterizes prediction errors resulting from their use. Methods are presented to estimate TAFs and their spatial and temporal variability and used to analyze total, commercial and non-commercial traffic in the Detroit, Michigan, U.S. metropolitan area. The variability of total volume estimates, quantified by the coefficient of variation (COV) representing the percentage departure from expected hourly volume, was 21, 33, 24 and 33% for weekdays, Saturdays, Sundays and holidays, respectively. Prediction errors mostly resulted from hour-to-hour variability on weekdays and Saturdays, and from day-to-day variability on Sundays and holidays. Spatial variability was limited across the study roads, most of which were large freeways. Commercial traffic had different temporal patterns and greater variability than noncommercial vehicle traffic, e.g., the weekday variability of hourly commercial volume was 28%. The results indicate that TAFs for a metropolitan region can provide reasonably accurate estimates of hourly vehicle volume on major roads. While vehicle volume is only one of many factors that govern on-road emission rates, air quality analyses would be strengthened by incorporating information regarding the uncertainty and variability of traffic activity. PMID:26688671

A comparison of freeway median crash frequency, severity, and barrier strike outcomes by median barrier type.

PubMed

Russo, Brendan J; Savolainen, Peter T

2018-08-01

Median-crossover crashes are among the most hazardous events that can occur on freeways, often resulting in severe or fatal injuries. The primary countermeasure to reduce the occurrence of such crashes is the installation of a median barrier. When installation of a median barrier is warranted, transportation agencies are faced with the decision among various alternatives including concrete barriers, beam guardrail, or high-tension cable barriers. Each barrier type differs in terms of its deflection characteristics upon impact, the required installation and maintenance costs, and the roadway characteristics (e.g., median width) where installation would be feasible. This study involved an investigation of barrier performance through an in-depth analysis of crash frequency and severity data from freeway segments where high-tension cable, thrie-beam, and concrete median barriers were installed. A comprehensive manual review of crash reports was conducted to identify crashes in which a vehicle left the roadway and encroached into the median. This review also involved an examination of crash outcomes when a barrier strike occurred, which included vehicle containment, penetration, or re-direction onto the travel lanes. The manual review of crash reports provided critical supplementary information through narratives and diagrams not normally available through standard fields on police crash report forms. Statistical models were estimated to identify factors that affect the frequency, severity, and outcomes of median-related crashes, with particular emphases on differences between segments with varying median barrier types. Several roadway-, traffic-, and environmental-related characteristics were found to affect these metrics, with results varying across the different barrier types. The results of this study provide transportation agencies with important guidance as to the in-service performance of various types of median barrier. Copyright © 2018 Elsevier Ltd. All rights reserved.

Transition metals in coarse, fine, very fine and ultra-fine particles from an interstate highway transect near Detroit

NASA Astrophysics Data System (ADS)

Cahill, Thomas A.; Barnes, David E.; Lawton, Jonathan A.; Miller, Roger; Spada, Nicholas; Willis, Robert D.; Kimbrough, Sue

2016-11-01

As one component of a study investigating the impact of vehicle emissions on near-road air quality, human exposures, and potential health effects, particles were measured from September 21 to October 30, 2010 on both sides of a major roadway (Interstate-96) in Detroit. Traffic moved freely on this 12 lane freeway with a mean velocity of 69 mi/hr. with little braking and acceleration. The UC Davis DELTA Group rotating drum (DRUM) impactors were used to collect particles in 8 size ranges at sites nominally 100 m south, 10 m north, 100 m north, and 300 m north of the highway. Ultra-fine particles were continuously collected at the 10 m north and 100 m north sites. Samples were analyzed every 3 h for mass (soft beta ray transmission), 42 elements (synchrotron-induced x-ray fluorescence) and optical attenuation (350-800 nm spectroscopy). A three day period of steady southerly winds along the array allowed direct measurement of freeway emission rates for coarse (10 > Dp > 1.0 μm), PM2.5, very fine (0.26 > Dp > 0.09 μm), and ultra-fine (Dp < 0.09 μm) particles. The PM2.5 mass concentrations were modeled using literature emission rates during the south to north wind periods, and averaged 1.6 ± 0.5 μg/m3, versus the measured value of 2.0 ± 0.7 μg/m3. Using European freeway emission rates from 2010, and modeling them at the I-96 site, we would predict roughly 3.1 μg/m3 of PM2.5 particles, corrected from the 4.9 PM10 value by their measured road dust contributions. Using California car and truck emission rates of 1973, this value would have been about 16 μg/m3, corrected down from the 19 μg/m3 PM5.0 using measured roadway dust contributions. This would have included 2.7 μg/m3 of lead, versus the 0.0033 μg/m3 measured. Very fine particles were distributed across the array with a relatively weak falloff versus distance. For the ultra-fine particles, emissions of soot and metals seen in vehicular braking studies correlated with traffic at the 10 m site, but only the soot was statistically significant at the 100 m north site. Otherwise, the 10 m north and 100 m north sites were essentially identical in mean concentration and highly correlated in time for most of the 5 week study. This result supports earlier publications showing the ability of very fine and ultra-fine particles to transport to sites well removed from the freeway sources. The concentrations of very fine and ultra-fine metals from brake wear and zinc in motor oil observed in Detroit have the potential of being a significant component in statistically established PM2.5 mortality rates.

Incorporating real-time traffic and weather data to explore road accident likelihood and severity in urban arterials.

PubMed

Theofilatos, Athanasios

2017-06-01

The effective treatment of road accidents and thus the enhancement of road safety is a major concern to societies due to the losses in human lives and the economic and social costs. The investigation of road accident likelihood and severity by utilizing real-time traffic and weather data has recently received significant attention by researchers. However, collected data mainly stem from freeways and expressways. Consequently, the aim of the present paper is to add to the current knowledge by investigating accident likelihood and severity by exploiting real-time traffic and weather data collected from urban arterials in Athens, Greece. Random Forests (RF) are firstly applied for preliminary analysis purposes. More specifically, it is aimed to rank candidate variables according to their relevant importance and provide a first insight on the potential significant variables. Then, Bayesian logistic regression as well finite mixture and mixed effects logit models are applied to further explore factors associated with accident likelihood and severity respectively. Regarding accident likelihood, the Bayesian logistic regression showed that variations in traffic significantly influence accident occurrence. On the other hand, accident severity analysis revealed a generally mixed influence of traffic variations on accident severity, although international literature states that traffic variations increase severity. Lastly, weather parameters did not find to have a direct influence on accident likelihood or severity. The study added to the current knowledge by incorporating real-time traffic and weather data from urban arterials to investigate accident occurrence and accident severity mechanisms. The identification of risk factors can lead to the development of effective traffic management strategies to reduce accident occurrence and severity of injuries in urban arterials. Copyright © 2017 Elsevier Ltd and National Safety Council. All rights reserved.

Driver speed selection on high-speed two-lane highways: Comparing speed profiles between uniform and differential speed limits.

PubMed

Russo, Brendan J; Savolainen, Peter T; Gates, Timothy J; Kay, Jonathan J; Frazier, Sterling

2017-07-04

Although a considerable amount of prior research has investigated the impacts of speed limits on traffic safety and operations, much of this research, and nearly all of the research related to differential speed limits, has been specific to limited access freeways. The unique safety and operational issues on highways without access control create difficulty relating the conclusions from prior freeway-related speed limit research to 2-lane highways, particularly research on differential limits due to passing limitations and subsequent queuing. Therefore, the objective of this study was to assess differences in driver speed selection with respect to the posted speed limit on rural 2-lane highways, with a particular emphasis on the differences between uniform and differential speed limits. Data were collected from nearly 59,000 vehicles across 320 sites in Montana and 4 neighboring states. Differences in mean speeds, 85th percentile speeds, and the standard deviation in speeds for free-flowing vehicles were examined across these sites using ordinary least squares regression models. Ultimately, the results of the analysis show that the mean speed, 85th percentile speed, and variability in travel speeds for free-flowing vehicles on 2-lane highways are generally lower at locations with uniform 65 mph speed limits, compared to locations with differential limits of 70 mph for cars and 60 mph for trucks. In addition to posted speed limits, several site characteristics were shown to influence speed selection including shoulder widths, frequency of horizontal curves, percentage of the segment that included no passing zones, and hourly volumes. Differences in vehicle speed characteristics were also observed between states, indicating that speed selection may also be influenced by local factors, such as driver population or enforcement.

A driving simulator study of driver performance on deceleration lanes.

PubMed

Calvi, A; Benedetto, A; De Blasiis, M R

2012-03-01

Deceleration lanes are important because they help drivers transition from high-speed lanes to low-speed ramps. Although they are designed to allow vehicles to depart the freeway safely and efficiently, many studies report high accident rates on exit ramps with the highest percentage of crashes taking place in deceleration lanes. This paper describes the results of a driving simulator study that focused on driving performance while approaching a divergence area and decelerating during the exiting maneuver. Three different traffic scenarios were simulated to analyze the influence of traffic volume on driving performance. Thirty drivers drove in the simulator in these scenarios while data on their lateral position, speed and deceleration were collected. Our results indicate there are considerable differences between the main assumptions of models generally used to design deceleration lanes and actual driving performance. In particular, diverging drivers begin to decelerate before arriving at the deceleration lane, causing interference with the main flow. Moreover, speeds recorded at the end of the deceleration lane exceed those for which the ramp's curves are designed; this creates risky driving conditions that could explain the high crash rates found in studies of exit ramps. Finally, statistical analyses demonstrate significant influences of traffic volume on some aspects of exiting drivers' performance: lower traffic volume results in elevated exiting speed and deceleration, and diverging drivers begin to decelerate earlier along the main lane when traffic volume is low. However, speeds at the end of the deceleration lane and the site of lane changing are not significantly influenced by traffic volume. Copyright © 2011 Elsevier Ltd. All rights reserved.

Freeway management handbook

DOT National Transportation Integrated Search

1997-08-01

This handbook, 1997 Freeway Management Handbook, is an update of the 1983 Freeway Management Handbook and reflects the tremendous developments in computing and communications technology. It also reflects the importance of Integrated Transportation Ma...

Modeling when and where a secondary accident occurs.

PubMed

Wang, Junhua; Liu, Boya; Fu, Ting; Liu, Shuo; Stipancic, Joshua

2018-01-31

The occurrence of secondary accidents leads to traffic congestion and road safety issues. Secondary accident prevention has become a major consideration in traffic incident management. This paper investigates the location and time of a potential secondary accident after the occurrence of an initial traffic accident. With accident data and traffic loop data collected over three years from California interstate freeways, a shock wave-based method was introduced to identify secondary accidents. A linear regression model and two machine learning algorithms, including a back-propagation neural network (BPNN) and a least squares support vector machine (LSSVM), were implemented to explore the distance and time gap between the initial and secondary accidents using inputs of crash severity, violation category, weather condition, tow away, road surface condition, lighting, parties involved, traffic volume, duration, and shock wave speed generated by the primary accident. From the results, the linear regression model was inadequate in describing the effect of most variables and its goodness-of-fit and accuracy in prediction was relatively poor. In the training programs, the BPNN and LSSVM demonstrated adequate goodness-of-fit, though the BPNN was superior with a higher CORR and lower MSE. The BPNN model also outperformed the LSSVM in time prediction, while both failed to provide adequate distance prediction. Therefore, the BPNN model could be used to forecast the time gap between initial and secondary accidents, which could be used by decision makers and incident management agencies to prevent or reduce secondary collisions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Freeway travel-time estimation and forecasting.

DOT National Transportation Integrated Search

2012-09-01

This project presents a microsimulation-based framework for generating short-term forecasts of travel time on freeway corridors. The microsimulation model that is developed (GTsim), replicates freeway capacity drop and relaxation phenomena critical f...

Modeling cooperative driving behavior in freeway merges.

DOT National Transportation Integrated Search

2011-11-01

Merging locations are major sources of freeway bottlenecks and are therefore important for freeway operations analysis. Microscopic simulation tools have been successfully used to analyze merging bottlenecks and to design optimum geometric configurat...

Scenario analysis of freight vehicle accident risks in Taiwan.

PubMed

Tsai, Ming-Chih; Su, Chien-Chih

2004-07-01

This study develops a quantitative risk model by utilizing Generalized Linear Interactive Model (GLIM) to analyze the major freight vehicle accidents in Taiwan. Eight scenarios are established by interacting three categorical variables of driver ages, vehicle types and road types, each of which contains two levels. The database that consists of 2043 major accidents occurring between 1994 and 1998 in Taiwan is utilized to fit and calibrate the model parameters. The empirical results indicate that accident rates of freight vehicles in Taiwan were high in the scenarios involving trucks and non-freeway systems, while; accident consequences were severe in the scenarios involving mature drivers or non-freeway systems. Empirical evidences also show that there is no significant relationship between accident rates and accident consequences. This is to stress that safety studies that describe risk merely as accident rates rather than the combination of accident rates and consequences by definition might lead to biased risk perceptions. Finally, the study recommends using number of vehicle as an alternative of traffic exposure in commercial vehicle risk analysis. The merits of this would be that it is simple and thus reliable; meanwhile, the resulted risk that is termed as fatalities per vehicle could provide clear and direct policy implications for insurance practices and safety regulations.

Highway Safety Manual applied in Missouri - freeway/software : research summary.

DOT National Transportation Integrated Search

2016-03-01

AASHTOs Highway Safety Manual (HSM) : includes models for freeway segments, speedchange : lanes (transitional area between mainline : and ramps), ramps, and interchange terminals. : These predictive models for freeway : interchanges need to be cal...

Improve FREQ macroscopic freeway analysis model

DOT National Transportation Integrated Search

2008-07-01

The primary objectives of this project have been to provide technical assistance on district freeway analysis projects, enhance the FREQ model based on guidance and suggestions from Caltrans staff members, and offer three freeway analysis workshops f...

A resilience-oriented approach for quantitatively assessing recurrent spatial-temporal congestion on urban roads.

PubMed

Tang, Junqing; Heinimann, Hans Rudolf

2018-01-01

Traffic congestion brings not only delay and inconvenience, but other associated national concerns, such as greenhouse gases, air pollutants, road safety issues and risks. Identification, measurement, tracking, and control of urban recurrent congestion are vital for building a livable and smart community. A considerable amount of works has made contributions to tackle the problem. Several methods, such as time-based approaches and level of service, can be effective for characterizing congestion on urban streets. However, studies with systemic perspectives have been minor in congestion quantification. Resilience, on the other hand, is an emerging concept that focuses on comprehensive systemic performance and characterizes the ability of a system to cope with disturbance and to recover its functionality. In this paper, we symbolized recurrent congestion as internal disturbance and proposed a modified metric inspired by the well-applied "R4" resilience-triangle framework. We constructed the metric with generic dimensions from both resilience engineering and transport science to quantify recurrent congestion based on spatial-temporal traffic patterns and made the comparison with other two approaches in freeway and signal-controlled arterial cases. Results showed that the metric can effectively capture congestion patterns in the study area and provides a quantitative benchmark for comparison. Also, it suggested not only a good comparative performance in measuring strength of proposed metric, but also its capability of considering the discharging process in congestion. The sensitivity tests showed that proposed metric possesses robustness against parameter perturbation in Robustness Range (RR), but the number of identified congestion patterns can be influenced by the existence of ϵ. In addition, the Elasticity Threshold (ET) and the spatial dimension of cell-based platform differ the congestion results significantly on both the detected number and intensity. By tackling this conventional problem with emerging concept, our metric provides a systemic alternative approach and enriches the toolbox for congestion assessment. Future work will be conducted on a larger scale with multiplex scenarios in various traffic conditions.

Digging West Oakland : what archaeologists found under the Cypress Freeway.

DOT National Transportation Integrated Search

2005-01-01

In 1989, the Loma Prieta earthquake destroyed 1.25 miles of the double-deck Cypress Freeway in Oakland, California. In realigning and rebuilding the freeway, the California Department of Transportation (Caltrans) undertook to identify any important a...

Twin Cities ramp meter evaluation : evaluation plan

DOT National Transportation Integrated Search

2000-09-25

The Minnesota Department of Transportation (Mn/DOT) uses ramp meters to manage freeway access on approximately 210 miles of freeways in the Twin Cities metropolitan area. Mn/DOT first tested ramp meters in 1969 as a method to optimize freeway safety ...

Innovative methods for calculation of freeway travel time using limited data : final report.

DOT National Transportation Integrated Search

2008-01-01

Description: Travel time estimations created by processing of simulated freeway loop detector data using proposed method have been compared with travel times reported from VISSIM model. An improved methodology was proposed to estimate freeway corrido...

The effects of in-vehicle tasks and time-gap selection while reclaiming control from adaptive cruise control (ACC) with bus simulator.

PubMed

Lin, Tsang-Wei; Hwang, Sheue-Ling; Su, Jau-Ming; Chen, Wan-Hui

2008-05-01

This research aimed to find out the effects of in-vehicle distractions and time-gap settings with a fix-based bus driving simulator in a following scenario. Professional bus drivers were recruited to perform in-vehicle tasks while driving with adaptive cruise control (ACC) of changeable time-gap settings in freeway traffic. Thirty subjects were divided equally into three groups for different in-vehicle task modes (between subjects), including no task distraction, hands-free, and manual modes. Further, time-gap settings for the experimental ACC were: shorter than 1.0 s, 1.0-1.5 s, 1.5-2.0 s, and longer than 2.0 s (within subjects). Longitudinal (mean headway, forward collision rate, and response time) and lateral control (mean lateral lane position and its standard deviation) performance was assessed. In the results, longitudinal control performance was worsened by both shorter time-gaps and heavier in-vehicle tasks. But the interaction indicated that the harm by heavier in-vehicle distraction could be improved by longer time-gaps. As for the lateral control, it would only be negatively affected by shorter time-gap settings. This research indicates the effects of time-gaps and in-vehicle distraction, as well as the interaction. Proper time-gap selection under different in-vehicle distractions can help avoid accidents and keep safe.

Investigation of contributing factors regarding wrong-way driving on freeways.

DOT National Transportation Integrated Search

2012-10-01

In Illinois, there were 217 wrong-way crashes on freeways from 2004 to 2009, resulting in 44 killed and : 248 injured. This research project sought to determine the contributing factors to wrong-way crashes on : freeways and to develop promising, cos...

Analysis of crash characteristics on freeways with depressed medians in Southcentral Alaska.

DOT National Transportation Integrated Search

2017-05-09

The characteristics of crashes on depressed medians of four freeways in Southcentral Alaska were examined under winter conditions. Cross-median crashes (CMC) were dispersed randomly along the freeways analyzed. CMC were 2.5 times likely to cause a se...

0-6811 : reducing lane and shoulder width to permit an additional lane on a freeway.

DOT National Transportation Integrated Search

2015-03-01

This research identified the operational and : safety implications of using reduced lane and : shoulder widths for a variety of freeway : configurations. As demand on Texas freeways : continues to increase, it is important to better : understand the ...

Adsorption of heavy metal in freeway by asphalt block

NASA Astrophysics Data System (ADS)

Zheng, Chaocheng

2017-08-01

Heavy metals are toxic, persistent, and carcinogenic in freeway. Various techniques are available for the removal of heavy metals from waste water among soils during freeway including ion-exchange, membrane filtration, electrolysis, coagulation, flotation, and adsorption. Among them, bio-sorption processes are widely used for heavy metal and other pollutant removal due to its sustainable, rapid and economic. In this paper, heavy metal removal facilitated by adsorption in plants during freeway was illustrated to provide concise information on exploring the adsorption efficiency.

On the measurement and valuation of travel time variability due to incidents on freeways

DOT National Transportation Integrated Search

1999-12-01

Incidents on freeways frequently cause long, unanticipated delays, increasing the economic cost of travel to motorists. This paper provides a simple model for estimating the mean and variance of time lost due to incidents on freeways. It also reviews...

Reducing lane and shoulder width to permit an additional lane on a freeway : technical report.

DOT National Transportation Integrated Search

2015-03-01

This research effort identified the operational and safety implications of using reduced lane and : shoulder widths for a variety of freeway configurations. The research team used speed, crash, and geometric : data for freeways in Dallas, Houston, an...

Nilsson's Power Model connecting speed and road trauma: applicability by road type and alternative models for urban roads.

PubMed

Cameron, M H; Elvik, R

2010-11-01

Nilsson (1981) proposed power relationships connecting changes in traffic speeds with changes in road crashes at various levels of injury severity. Increases in fatal crashes are related to the 4(th) power of the increase in mean speed, increases in serious casualty crashes (those involving death or serious injury) according to the 3(rd) power, and increases in casualty crashes (those involving death or any injury) according to the 2(nd) power. Increases in numbers of crash victims at cumulative levels of injury severity are related to the crash increases plus higher powers predicting the number of victims per crash. These relationships are frequently applied in OECD countries to estimate road trauma reductions resulting from expected speed reductions. The relationships were empirically derived based on speed changes resulting from a large number of rural speed limit changes in Sweden during 1967-1972. Nilsson (2004) noted that there had been very few urban speed limit changes studied to test his power model. This paper aims to test the assumption that the model is equally applicable in all road environments. It was found that the road environment is an important moderator of Nilsson's power model. While Nilsson's model appears satisfactory for rural highways and freeways, the model does not appear to be directly applicable to traffic speed changes on urban arterial roads. The evidence of monotonically increasing powers applicable to changes in road trauma at increasing injury severity levels with changes in mean speed is weak. The estimated power applicable to serious casualties on urban arterial roads was significantly less than that on rural highways, which was also significantly less than that on freeways. Alternative models linking the parameters of speed distributions with road trauma are reviewed and some conclusions reached for their use on urban roads instead of Nilsson's model. Further research is needed on the relationships between serious road trauma and urban speeds. 2010 Elsevier Ltd. All rights reserved.

Improved chain control operations.

DOT National Transportation Integrated Search

2010-01-01

In California, field maintenance personnel use turntable signs to advise motorists of chain control conditions on rural : highways and freeways. To do this an operator has to park, exit the vehicle, turn the sign on the shoulder and then : walk acros...

Proactive assessment of accident risk to improve safety on a system of freeways.

DOT National Transportation Integrated Search

2012-05-01

This report describes the development and evaluation of real-time crash risk-assessment models for four freeway corridors: U.S. Route 101 NB (northbound) and SB (southbound) and Interstate 880 NB and SB. Crash data for these freeway segments for the ...

The Columbus metropolitan freeway management system (CMFMS) effectiveness study : part 2, the after study.

DOT National Transportation Integrated Search

2006-08-01

A Freeway Management System (FMS) employs various tools to manage a freeway to increase throughput and reduce delay : without additional lanes. The FMS acquires data from the roadway and process these data to identify and respond to : problems. If so...

Near-real-time trace element measurements in a rural, traffic-influenced environment with some fireworks

NASA Astrophysics Data System (ADS)

Furger, Markus; Slowik, Jay G.; Cruz Minguillón, María; Hueglin, Christoph; Koch, Chris; Prévôt, André S. H.; Baltensperger, Urs

2016-04-01

Aerosol-bound trace elements can affect the environment in significant ways especially when they are toxic. Characterizing the trace element spatial and temporal variability is a prerequisite for human exposure studies. The requirement for high time resolution and consequently the low sample masses asked for analysis methods not easily accessible, such as synchrotron radiation-induced X-ray fluorescence spectrometry (SR-XRF). In recent years, instrumentation that samples and analyzes airborne particulate matter with time resolutions of less than an hour in near real time has entered the market. We present the results of a three-week campaign in a rural environment close to a freeway. The measurement period included the fireworks of the Swiss National Day. The XRF instrument was set up at the monitoring station Härkingen of the Swiss Monitoring Network for Air Pollution (NABEL). It was configured to sample and analyze ambient PM10 aerosols in 1-hour intervals. Sample analysis with XRF was performed by the instrument immediately after collection, i.e. during the next sampling interval. 24 elements were analyzed and quantified (Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Sn, Sb, Ba, Pt, Hg, Pb, Bi). The element concentrations obtained by the XRF instrument were compared to those determined by ICP-AES and ICP-MS in PM10 samples collected by NABEL high volume samplers. The results demonstrate the capability of the instrument to measure over a wide range of concentrations, from a few ng m-3 to μg m-3, under ambient conditions. The time resolution allows for the characterization of diurnal variations of element concentrations, which provides information on the contribution of emission sources, such as road traffic, soil, or fireworks. Some elements (V, Co, As, Pt) were below their detection limit during most of the time, but As could be quantified during the fireworks. Transition metals Cr, Mn, Fe, Cu, Zn could be attributed to freeway traffic. K, S, Ba, and Bi were strongly linked to the fireworks. The field test provided good evidence for the applicability and ease of use of the instrument. It provided also an idea on the sensitivity of the method in realistic, ambient conditions, although the 3-week period was too short for a thorough assessment, e.g. for different weather conditions.

The development of local calibration factors - phase II : Maryland freeways and ramps : final report.

DOT National Transportation Integrated Search

2016-11-01

The goal of the study was to develop local calibration factors (LCFs) for Maryland freeways in order to apply the predictive methods of the Highway Safety Manual (HSM) to the state. LCFs were computed for freeway segments, speed-change lanes, and sig...

Integration of off-ramp and arterial signal controls to minimize the recurrent congestion on the I-495 Capital Beltway.

DOT National Transportation Integrated Search

2010-11-01

This study developed an integrated control model to contend with the impact of off-ramp queue spillback on both the freeway and arterials within the interchange control boundaries. The entire control system consists of two levels that compute the opt...

Development of an accident duration prediction model on the Korean Freeway Systems.

PubMed

Chung, Younshik

2010-01-01

Since duration prediction is one of the most important steps in an accident management process, there have been several approaches developed for modeling accident duration. This paper presents a model for the purpose of accident duration prediction based on accurately recorded and large accident dataset from the Korean Freeway Systems. To develop the duration prediction model, this study utilizes the log-logistic accelerated failure time (AFT) metric model and a 2-year accident duration dataset from 2006 to 2007. Specifically, the 2006 dataset is utilized to develop the prediction model and then, the 2007 dataset was employed to test the temporal transferability of the 2006 model. Although the duration prediction model has limitations such as large prediction error due to the individual differences of the accident treatment teams in terms of clearing similar accidents, the results from the 2006 model yielded a reasonable prediction based on the mean absolute percentage error (MAPE) scale. Additionally, the results of the statistical test for temporal transferability indicated that the estimated parameters in the duration prediction model are stable over time. Thus, this temporal stability suggests that the model may have potential to be used as a basis for making rational diversion and dispatching decisions in the event of an accident. Ultimately, such information will beneficially help in mitigating traffic congestion due to accidents.

Impact of a freeway on the dispersal of ticks and Ixodes ricinus-borne pathogens: forested resting areas may become Lyme disease hotspots.

PubMed

Hornok, Sándor; Mulvihill, Maria; Szőke, Krisztina; Gönczi, Enikő; Sulyok, Kinga M; Gyuranecz, Miklós; Hofmann-Lehmann, Regina

2017-06-01

Man-made barriers are well known for their effects on ecosystems. Habitat fragmentation, for instance, is a recognised consequence of modern-day infrastructure. The aim of the present study was to investigate the diversity and abundance of tick species, as well as the risks of acquiring tick-borne infections in habitats adjacent to a freeway. Therefore, ixodid ticks were collected from the vegetation at two-week intervals (in the main tick season, from March to June) in eight habitats of different types (forest, grove, grassland) along both sides of a freeway. Ixodes ricinus females were molecularly screened for three species of tick-borne bacteria. In the study period, 887 ixodid ticks were collected. These included 704 I. ricinus (79.4%), 51 Dermacentor reticulatus (5.7%), 78 D. marginatus (8.8%), 35 Haemaphysalis inermis (3.9%) and 19 H. concinna (2.1%). There was no significant difference in the abundance of tick species between similar habitats separated by the freeway, except for the absence of Dermacentor spp. on one side. In I. ricinus females, the overall prevalence of Anaplasma phagocytophilum was low, and (in part due to this low rate) did not show significant difference between the two sides of the freeway. Rickettsia helvetica had significantly different overall prevalence between two distant habitats along the same side of the freeway (12.3% vs. 31.4%), but not between habitats on the opposite sides. Borrelia burgdorferi s.l. showed significantly different overall prevalence between habitats both on the same and on the opposite sides of the freeway (8.6-35.9%), and the difference was higher if relevant habitats were also separated by the freeway. Importantly, the prevalence rate of the Lyme disease agent was highest in a forested resting area of the freeway, and was significantly inversely proportional to the prevalence of A. phagocytophilum (taking into account all evaluated habitats), apparently related to deer population density. Prevalence rates of these bacteria also differed significantly on single sampling occasions between: (1) closely situated habitats of different types; (2) distant and either similar or different habitat types; and (3) habitats on the opposite sides of the freeway. In conclusion, the findings of the present study show that a fenced freeway may contribute to differences in tick species diversity and tick-borne pathogen prevalence along its two sides, and this effect is most likely a consequence of its barrier role preventing deer movements.

Control Strategies for Corridor Management

DOT National Transportation Integrated Search

2016-06-28

Integrated management of travel corridors comprising of freeways and adjacent arterial streets can potentially improve the performance of the highway facilities. However, several research gaps exist in data collection and performance measurement, ana...

A dynamic feedback-control toll pricing methodology : a case study on Interstate 95 managed lanes.

DOT National Transportation Integrated Search

2013-06-01

Recently, congestion pricing emerged as a cost-effective and efficient strategy to mitigate the congestion problem on freeways. This study develops a feedback-control based dynamic toll approach to formulate and solve for optimal tolls. The study com...

Air quality impacts of transit improvement, preferential lane, and carpool/vanpool programs. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiRenzo, J.F.; Rubin, R.B.

1978-03-01

The report was prepared in accordance with Section 108(f) of the Clean Air Act, as amended, August 1977. It is intended to assist urban areas in developing State Implementation Plans and integrating their transportation system management and air quality planning programs as required by FHWA, UMTA, and EPA. The report analyzes the air quality, travel, energy consumption, economic, and cost impacts of three types of transportation programs: priority treatment for high occupancy vehicles on freeways and arterials; areawide carpool and vanpool programs; and transit fare reductions and service improvements. Important factors (e.g., meteorological conditions, traffic volumes and speeds, and changesmore » in modal choice) likely to influence air quality and emissions for the above programs are also analyzed.« less

Evaluation of road expansion and connectivity mitigation for wildlife in southern California

USGS Publications Warehouse

Alonso, Robert S.; Lyren, Lisa M.; Boydston, Erin E.; Haas, Christopher D.; Crooks, Kevin R.

2014-01-01

We designed a remote-camera survey to study how the expansion of California State Route 71 (CA-71) and implementation of connectivity mitigation affected the use of underpasses by large mammals in southern California. Based on detections by cameras, the use of underpasses by bobcats (Lynx rufus) was higher within the area of expansion and mitigation after construction than before, but there was no difference in use of underpasses in the impact zone compared to the control zone before or after construction. Use of underpasses by coyotes (Canis latrans) was higher in the control zone than in the impact zone, but there was no difference in use before and after construction. Small numbers of detections of mule deer (Odocoileus hemionus) at only a few underpasses precluded comparison between control and impact zones. However, a comparison of use before and after construction revealed that use of underpasses by mule deer was slightly higher post-construction. We cannot fully attribute increased detections post-construction to mitigative efforts, because other factors, such as availability of habitat, urbanization, or demography, also may have influenced use of underpasses along CA-71. Nonetheless, even with the expansion of the freeway and subsequent increase in volume of traffic, mitigative structures along CA-71 did allow for continued movement and, hence, connectivity across the roadway for large mammals.

Suitability of Synthetic Driving Profiles from Traffic Micro-Simulation for Real-World Energy Analysis: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hou, Yunfei; Wood, Eric; Burton, Evan

A shift towards increased levels of driving automation is generally expected to result in improved safety and traffic congestion outcomes. However, little empirical data exists to estimate the impact that automated driving could have on energy consumption and greenhouse gas emissions. In the absence of empirical data on differences between drive cycles from present day vehicles (primarily operated by humans) and future vehicles (partially or fully operated by computers) one approach is to model both situations over identical traffic conditions. Such an exercise requires traffic micro-simulation to not only accurately model vehicle operation under high levels of automation, but alsomore » (and potentially more challenging) vehicle operation under present day human drivers. This work seeks to quantify the ability of a commercial traffic micro-simulation program to accurately model real-world drive cycles in vehicles operated primarily by humans in terms of driving speed, acceleration, and simulated fuel economy. Synthetic profiles from models of freeway and arterial facilities near Atlanta, Georgia, are compared to empirical data collected from real-world drivers on the same facilities. Empirical and synthetic drive cycles are then simulated in a powertrain efficiency model to enable comparison on the basis of fuel economy. Synthetic profiles from traffic micro-simulation were found to exhibit low levels of transient behavior relative to the empirical data. Even with these differences, the synthetic and empirical data in this study agree well in terms of driving speed and simulated fuel economy. The differences in transient behavior between simulated and empirical data suggest that larger stochastic contributions in traffic micro-simulation (relative to those present in the traffic micro-simulation tool used in this study) are required to fully capture the arbitrary elements of human driving. Interestingly, the lack of stochastic contributions from models of human drivers in this study did not result in a significant discrepancy between fuel economy simulations based on synthetic and empirical data; a finding with implications on the potential energy efficiency gains of automated vehicle technology.« less

Effect of traffic density on drivers' lane change and overtaking maneuvers in freeway situation - A driving simulator based study.

PubMed

Yang, Liu; Li, Xiaomeng; Guan, Wei; Zhang, H Michael; Fan, Lingling

2018-05-14

The aim of this study is to examine the effect of traffic density on drivers' lane change and overtaking maneuvers. The differences between drivers' left and right lane-changing/overtaking maneuvers were also investigated. A driving simulator experiment was conducted and 24 participants took part in this experiment. Based on the driving simulation data, lane change frequency, time duration, average speed and acceleration were extracted as key variables of lane change maneuvers; overtaking frequency, overtaking duration, initial overtaking distance and headway, instantaneous speed and acceleration before overtaking were analyzed as the key overtaking variables. One-way repeated measures ANOVA, Friedman test and Wilcoxon signed-rank test were adopted for hypothesis tests with significance level of 0.05. Further pairwise comparisons were performed with a Bonferroni correction for multiple comparisons. Some significant differences in lane change and overtake behaviors were observed among different traffic densities: 1) both lane change and overtaking frequencies significantly increase with traffic density; 2) the average lane change acceleration and instantaneous overtaking acceleration significantly increase with traffic density; 3) as the traffic density increases, the initial overtaking distance and headway decrease. As for the effect of the directions of maneuvers: 1) the time duration of lane change and overtaking from right side was significantly shorter than that from left side; 2) the right initial overtaking distance/headway was smaller than that of left side; 3) the right instantaneous overtaking acceleration was significantly higher than the left instantaneous acceleration. The results showed that as traffic density increases, drivers' intention for lane change and overtaking is enhanced. Both initial overtaking distance and headway decrease with traffic density, which might influence road safety. In addition, drivers do not show a preference on the directions of lane change or overtaking according to the frequency. However, drivers tend to be more decisive and reckless when conducting the right overtaking because of a smaller distance/headway before overtaking, higher instantaneous acceleration and also a more restricted field of view compared with left overtaking.

Oxidative potential of on-road fine particulate matter (PM2.5) measured on major freeways of Los Angeles, CA, and a 10-year comparison with earlier roadside studies

NASA Astrophysics Data System (ADS)

Shirmohammadi, Farimah; Wang, Dongbin; Hasheminassab, Sina; Verma, Vishal; Schauer, James J.; Shafer, Martin M.; Sioutas, Constantinos

2017-01-01

This study describes on-road measurements of fine particulate matter (PM2.5) using a mobile instrumentation platform to assess the chemical composition and oxidative potential of PM2.5, using the dithiothreitol (DTT) assay, over three representative roadways in the Los Angeles Basin: the I-110 and I-710 freeways, the Wilshire/Sunset boulevards as well as the main campus of the University of Southern California (USC), used as a reference urban background site. Samples were chemically analyzed for elemental carbon (EC), organic carbon (OC), polycyclic aromatic hydrocarbons (PAHs) and 50 elements. The cumulative mass fraction of the measured PAHs was highest on the freeways (0.16 ± 0.01 and 0.15 ± 0.01 ng/μg PM, on I-110 and I-710, respectively); which on average was 3 and 3.3-fold higher than at Wilshire/Sunset and USC site, respectively. Mass fractions of Ba, Cr, Cu, Mn, Ni, Pb, Sb and Zn, tracers of vehicular abrasion, were 3.8 ± 0.8 times higher on both freeways in comparison to Wilshire/Sunset. The observed intrinsic (normalized per PM mass) DTT activity was greatest on freeways, averaging 30.13 ± 3.15 nmol/min mg PM and being roughly 1.9 and 2.1 times higher than the values obtained at Wilshire/Sunset and USC, respectively. Furthermore, comparison of our results with previous on-road and roadside studies conducted in the last decade in Los Angeles indicated an overall reduction in the contribution of carbonaceous species and PAHs (important tracers of exhaust emissions) to PM mass, especially on I-710 freeway with the higher heavy-duty diesel vehicle fraction, indicating the effectiveness of diesel vehicle emissions control policies implemented in recent years in California. In contrast, greater contributions of certain groups of metals and trace elements that are indicators of non-tailpipe emissions compared to previous studies provide evidence on the increasing importance of non-tailpipe emissions to the oxidative potential of on-road PM2.5 as vehicular exhaust emissions becomes cleaner. This finding was also reflected in the increased levels of on-road DTT activity by factors of 1.4-1.5 in comparison to the DTT activity of vehicular emissions estimated in previous dynamometer studies.

Development of operating mode distributions for different types of roadways under different congestion levels for vehicle emission assessment using MOVES.

PubMed

Qi, Yi; Padiath, Ameena; Zhao, Qun; Yu, Lei

2016-10-01

The Motor Vehicle Emission Simulator (MOVES) quantifies emissions as a function of vehicle modal activities. Hence, the vehicle operating mode distribution is the most vital input for running MOVES at the project level. The preparation of operating mode distributions requires significant efforts with respect to data collection and processing. This study is to develop operating mode distributions for both freeway and arterial facilities under different traffic conditions. For this purpose, in this study, we (1) collected/processed geographic information system (GIS) data, (2) developed a model of CO2 emissions and congestion from observations, (3) implemented the model to evaluate potential emission changes from a hypothetical roadway accident scenario. This study presents a framework by which practitioners can assess emission levels in the development of different strategies for traffic management and congestion mitigation. This paper prepared the primary input, that is, the operating mode ID distribution, required for running MOVES and developed models for estimating emissions for different types of roadways under different congestion levels. The results of this study will provide transportation planners or environmental analysts with the methods for qualitatively assessing the air quality impacts of different transportation operation and demand management strategies.

The relative efficiency of Iranian's rural traffic police: a three-stage DEA model.

PubMed

Rahimi, Habibollah; Soori, Hamid; Nazari, Seyed Saeed Hashemi; Motevalian, Seyed Abbas; Azar, Adel; Momeni, Eskandar; Javartani, Mehdi

2017-10-13

Road traffic Injuries (RTIs) as a health problem imposes governments to implement different interventions. Target achievement in this issue required effective and efficient measures. Efficiency evaluation of traffic police as one of the responsible administrators is necessary for resource management. Therefore, this study conducted to measure Iran's rural traffic police efficiency. This was an ecological study. To obtain pure efficiency score, three-stage DEA model was conducted with seven inputs and three output variables. At the first stage, crude efficiency score was measured with BCC-O model. Next, to extract the effects of socioeconomic, demographic, traffic count and road infrastructure as the environmental variables and statistical noise, the Stochastic Frontier Analysis (SFA) model was applied and the output values were modified according to similar environment and statistical noise conditions. Then, the pure efficiency score was measured using modified outputs and BCC-O model. In total, the efficiency score of 198 police stations from 24 provinces of 31 provinces were measured. The annual means (standard deviation) of damage, injury and fatal accidents were 247.7 (258.4), 184.9 (176.9), and 28.7 (19.5), respectively. Input averages were 5.9 (3.0) patrol teams, 0.5% (0.2) manpower proportions, 7.5 (2.9) patrol cars, 0.5 (1.3) motorcycles, 77,279.1 (46,794.7) penalties, 90.9 (2.8) cultural and educational activity score, 0.7 (2.4) speed cameras. The SFA model showed non-significant differences between police station performances and the most differences attributed to the environmental and random error. One-way main road, by road, traffic count and the number of household owning motorcycle had significant positive relations with inefficiency score. The length of freeway/highway and literacy rate variables had negative relations, significantly. Pure efficiency score was with mean of 0.95 and SD of 0.09. Iran's traffic police has potential opportunity to reduce RTIs. Adjusting police performance with environmental conditions is necessary. Capability of DEA method in setting quantitative targets for every station induces motivation for managers to reduce RTIs. Repetition of this study is recommended, annually.

Characteristics of trace metals in traffic-derived particles in Hsuehshan Tunnel, Taiwan: size distribution, potential source, and fingerprinting metal ratio

NASA Astrophysics Data System (ADS)

Lin, Y.-C.; Tsai, C.-J.; Wu, Y.-C.; Zhang, R.; Chi, K.-H.; Huang, Y.-T.; Lin, S.-H.; Hsu, S.-C.

2015-04-01

Traffic emissions are a significant source of airborne particulate matter (PM) in ambient environments. These emissions contain an abundance of toxic metals and thus pose adverse effects on human health. Size-fractionated aerosol samples were collected from May to September 2013 by using micro-orifice uniform deposited impactors (MOUDIs). Sample collection was conducted simultaneously at the inlet and outlet sites of Hsuehshan Tunnel in northern Taiwan, which is the second-longest freeway tunnel (12.9 km) in Asia. This endeavor aims to characterize the chemical constituents and size distributions, as well as fingerprinting ratios of particulate metals emitted by vehicle fleets. A total of 36 metals in size-resolved aerosols were determined through inductively coupled plasma mass spectrometry. Three major groups - namely, tailpipe emissions (Zn, Pb, and V in fine mode), wear debris (Cu, Cd, Fe, Ga, Mn, Mo, Sb, and Sn), and resuspended dust (Ca, Mg, K, and Rb) - of airborne PM metals were categorized on the basis of the results of enrichment factor, correlation matrix, and principal component analysis. Size distributions of wear-originated metals resembled the pattern of crustal elements, which were predominated by super-micron particulates (PM1-10). By contrast, tailpipe exhaust elements such as Zn, Pb, and V were distributed mainly in submicron particles. By employing Cu as a tracer of wear abrasion, several inter-metal ratios - including Fe / Cu (14), Ba / Cu (1.05), Sb / Cu (0.16), Sn / Cu (0.10), and Ga / Cu (0.03) - served as fingerprints for wear debris. However, the data set collected in this work is useful for further studies on traffic emission inventory and human health effects of traffic-related PM.

Implementation guideline for non-freeway centerline rumble strips.

DOT National Transportation Integrated Search

2015-03-01

This document presents a guideline for the : implementation of non-freeway centerline rumble : strips on high speed rural highways. It includes : recommended practices, according to MDOT : standards, and describes effective strategies and : technique...

Estimation of capacities on Florida freeways.

DOT National Transportation Integrated Search

2014-09-01

Current capacity estimates within Floridas travel time reliability tools rely on the Highway Capacity Manual (HCM 2010) to : estimate capacity under various conditions. Field measurements show that the capacities of Florida freeways are noticeably...

Application of ERTS imagery in estimating the environmental impact of a freeway through the Knysna area of South Africa

NASA Technical Reports Server (NTRS)

Williamson, D. T.; Gilbertson, B.

1974-01-01

In the coastal areas north-east and south-west of Knysna, South Africa lie natural forests, lakes and lagoons highly regarded by many for their aesthetic and ecological richness. A freeway construction project has given rise to fears of the degradation or destruction of these natural features. The possibility was investigated of using ERTS imagery to estimate the environmental impact of the freeway and found that: (1) All threatened features could readily be identified on the imagery. (2) It was possible within a short time to provide an area estimate of damage to indigenous forest. (3) In several important respects the imagery has advantages over maps and aerial photos for this type of work. (4) The imagery will enable monitoring of the actual environmental impact of the freeway when completed.

Methodology for Calculating Latency of GPS Probe Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhongxiang; Hamedi, Masoud; Young, Stanley

Crowdsourced GPS probe data, such as travel time on changeable-message signs and incident detection, have been gaining popularity in recent years as a source for real-time traffic information to driver operations and transportation systems management and operations. Efforts have been made to evaluate the quality of such data from different perspectives. Although such crowdsourced data are already in widespread use in many states, particularly the high traffic areas on the Eastern seaboard, concerns about latency - the time between traffic being perturbed as a result of an incident and reflection of the disturbance in the outsourced data feed - havemore » escalated in importance. Latency is critical for the accuracy of real-time operations, emergency response, and traveler information systems. This paper offers a methodology for measuring probe data latency regarding a selected reference source. Although Bluetooth reidentification data are used as the reference source, the methodology can be applied to any other ground truth data source of choice. The core of the methodology is an algorithm for maximum pattern matching that works with three fitness objectives. To test the methodology, sample field reference data were collected on multiple freeway segments for a 2-week period by using portable Bluetooth sensors as ground truth. Equivalent GPS probe data were obtained from a private vendor, and their latency was evaluated. Latency at different times of the day, impact of road segmentation scheme on latency, and sensitivity of the latency to both speed-slowdown and recovery-from-slowdown episodes are also discussed.« less

Network Level Carbon Dioxide Emissions From On-road Sources in the Portland OR, (USA) Metropolitan Area

NASA Astrophysics Data System (ADS)

Powell, J.; Butenhoff, C. L.; Rice, A. L.

2014-12-01

To mitigate climate change, governments at multiple levels are developing policies to decrease anthropogenic carbon dioxide (CO2) emissions. The City of Portland (Oregon) and Multnomah County have adopted a Climate Action Plan with a stated goal of reducing emissions to 80% below 1990 levels by 2050. The transportation sector alone accounts for about 40% of total emissions in the Portland metropolitan area. Here we show a new street-level model of on-road mobile CO2 emissions for the Portland, OR metropolitan region. The model uses hourly traffic counter recordings made by the Portland Bureau of Transportation at 9,352 sites over 21 years (1986-2006), augmented with freeway loop detector data from the Portland Regional Transportation Archive Listing (PORTAL) transportation data archive. We constructed a land use regression model to fill in traffic network gaps with traffic counts as the dependent variable using GIS data such as road class (32 categories) and population density. The Environmental Protection Agency (EPA) MOtor Vehicle Emission Simulator (MOVES) model was used to estimate transportation CO2 emissions. The street-level emissions can be aggregated and gridded and used as input to atmospheric transport models for comparison with atmospheric measurements. This model also provides an independent assessment of top-down inventories that determine emissions from fuel sales, while being an important component of our ongoing effort to assess the effectiveness of emission mitigation strategies at the urban scale.

Freeway bottleneck removals : workshop enhancement and technology transfer.

DOT National Transportation Integrated Search

2009-12-01

As transportation improvement projects become increasingly costly and complex and as funding sources are not : keeping pace with needs in highly urbanized areas, it becomes critical that existing freeway systems be finetuned to : maximize capacity...

Operations-oriented performance measures for freeway management systems : final report.

DOT National Transportation Integrated Search

2008-12-01

This report describes the second and final year activities of the project titled Using Operations-Oriented Performance Measures to Support Freeway Management Systems. Work activities included developing a prototype system architecture for testi...

Detroit Corridor Evaluation Plan

DOT National Transportation Integrated Search

1998-01-01

THE GOALS OF THIS PROJECT ARE TO (1) MEASURE THE IMPACTS FROM INSTALLING THE EXISTING ITS FACILITIES, (2) DETERMINE WHETHER MOTORISTS' EXHIBIT A BIAS TOWARD FREEWAYS, (3) CALCULATE THE IMPACT OF FREEWAY BIAS, (3) IDENTIFY OPERATIONAL STRATEGIES THAT ...

Highway Safety Manual applied in Missouri - freeway/software.

DOT National Transportation Integrated Search

2016-06-01

AASHTOs Highway Safety Manual (HSM) facilitates the quantitative safety analysis of highway facilities. In a 2014 : supplement, freeway facilities were added to the original HSM manual which allows the modeling of highway : interchanges. This repo...

Review of heavy metal bio-remediation in contaminated freeway facilitated by adsorption

NASA Astrophysics Data System (ADS)

Zheng, Chaocheng

2017-08-01

Toxicity around biological systems is a significant issue for environmental health in a long term. Recent biotechnological approaches for bio-remediation of heavy metals in freeway frequently include mineralization, bio-adsorption or even remediation. Thus, adequate restoration in freeway requiring cooperation, integration and assimilation of such biotechnological advances along with traditional and ethical wisdom to unravel the mystery of nature in the emerging field of bio-remediation was reviewed with highlights to better understand problems associated with toxicity of heavy metals and eco-friendly technologies.

Assessing factors causing severe injuries in crashes of high-deck buses in long-distance driving on freeways.

PubMed

Chu, Hsing-Chung

2014-01-01

High-deck buses that have a higher center of gravity traveling at an excessive speed have a higher likelihood of causing serious and fatal accidents when drivers lose control of the vehicle. In addition, drivers who suffer from fatigue in long-distance driving increase the likelihood of serious accident. This paper examines the effects of risk factors contributing to severe crashes associated with high-deck buses used for long-distance driving on freeways. An ordered logit and latent class models are used to examine significant factors on the severity of injuries in crashes related to high-deck buses. Driver fatigue, drivers or passengers not wearing a seat belt, reckless driving, drunk driving, crashes occurred between midnight and dawn, and crashes occurred at interchange ramps were found to significantly affect the severity of injuries in crashes involving high-deck buses. Safety policies to prevent severe injuries in crashes involving high deck buses used for long-distance runs on freeways include: (1) restricting drivers from exceeding the limit of daily driving hours and mandating sufficient rest breaks; (2) installing an automatic sleep-warning device in the vehicle; (3) drivers with obstructive sleep apnea syndrome or sleep disorders should be tested and treated before they are allowed to perform long hours of driving tasks; (4) educating the public or even amending the seatbelt legislation to require all passengers to wear a seat belt and thus reduce the chance of ejection from a high-deck bus and prevent serious injuries in a crash while traveling at a higher speed on freeways. Copyright © 2013 Elsevier Ltd. All rights reserved.

Coordinated Freeway and Arterial Operations Handbook

DOT National Transportation Integrated Search

2006-05-01

Managing and operating freeways and adjacent arterials in a proactive and comprehensive manner, from a system user's perspective, is a major step toward operating all modes of the transportation system at maximum efficiency. The focus of this guide i...

Corridor-based forecasts of work-zone impacts for freeways.

DOT National Transportation Integrated Search

2011-08-09

This project developed an analysis methodology and associated software implementation for the evaluation of : significant work zone impacts on freeways in North Carolina. The FREEVAL-WZ software tool allows the analyst : to predict the operational im...

Trilogy Operational Test

DOT National Transportation Integrated Search

1998-09-29

The Trilogy project was an ITS demonstration of the broadcast of freeway system traveler information to both commercial and commuter drivers over a 25-mile (40.3 km) radius of the Twin : Cities metropolitan area. In this project, real-time freeway sy...

Safety performance functions for freeway merge zones.

DOT National Transportation Integrated Search

2013-12-01

This report documents the results of a research project to support CDOT in the area of Safety : Performance Function (SPF) development. The project involved collecting data and developing SPFs for : ramp-freeway merge zones categorized as isolated, n...

Impact of non-freeway rumble strips phase 1.

DOT National Transportation Integrated Search

2012-06-26

In an effort to reduce lane-departure crashes, in 2008 the Michigan Department of Transportation (MDOT) began a : three-year statewide non-freeway rumble strip installation initiative. This initiative called for the installation of : milled centerlin...

Joint measurements of black carbon and particle mass for heavy-duty diesel vehicles using a portable emission measurement system

NASA Astrophysics Data System (ADS)

Zheng, Xuan; Wu, Ye; Zhang, Shaojun; Baldauf, Richard W.; Zhang, K. Max; Hu, Jingnan; Li, Zhenhua; Fu, Lixin; Hao, Jiming

2016-09-01

The black carbon (BC) emitted from heavy-duty diesel vehicles (HDDVs) is an important source of urban atmospheric pollution and creates strong climate-forcing impacts. The emission ratio of BC to total particle mass (PM) (i.e., BC/PM ratio) is an essential variable used to estimate total BC emissions from historical PM data; however, these ratios have not been measured using portable emission measurement systems (PEMS) in order to obtain real-world measurements over a wide range of driving conditions. In this study, we developed a PEMS platform by integrating two Aethalometers and an electric low pressure impactor to realize the joint measurement of real-world BC and PM emissions for ten HDDVs in China. Test results showed that the average BC/PM ratio for five HDDVs equipped with mechanical fuel injection (MI) engines was 0.43 ± 0.06, significantly lower (P < 0.05) than another five HDDVs equipped with electronically-controlled fuel injection (EI) engines (0.56 ± 0.12). Traffic conditions also affected the BC/PM ratios with higher ratios on freeway routes than on local roads. Furthermore, higher ratios were observed for HDDVs equipped with EI engines than for the MI engines for the highway and local road routes. With an operating mode binning approach, we observed that the instantaneous BC/PM ratios of EI engine vehicles were above those of the MI engine vehicles in all operating modes except for the braking mode (i.e., Bin 0). Therefore, the complex impacts from engine technology and traffic conditions on BC/PM ratios should be carefully considered when estimating real-world BC emissions from HDDVs based on overall PM emissions data.

Feasibility study for a freeway corridor infrastructure health monitoring instrumentation testbed.

DOT National Transportation Integrated Search

2012-08-01

With current and near-term construction activities within the freeway system of Southeast Wisconsin, there is a unique : opportunity to develop a detailed understanding of their in-service performance by implementing a health monitoring : network tha...

Evaluation of dual-loop data accuracy using video ground truth data

DOT National Transportation Integrated Search

2002-01-01

Washington State Department of Transportation (WSDOT) initiated a : research project entitled Monitoring Freight on Puget Sound Freeways in September : 1999. Dual-loop data from the Seattle area freeway system were selected as the main data : s...

Implementing the Routine Computation and Use of Roadway Performance Measures within WSDOT

DOT National Transportation Integrated Search

2017-08-01

The Washington State Department of Transportation (WSDOT) is one of the nation's leaders in calculating and using reliability statistics for urban freeways. The Department currently uses reliability measures for decision making for urban freeways-whe...

Data-driven freeway performance evaluation framework for project prioritization and decision making.

DOT National Transportation Integrated Search

2017-01-01

This report describes methods that potentially can be incorporated into the performance monitoring and planning processes for freeway performance evaluation and decision making. Reliability analysis was conducted on the selected I-15 corridor by empl...

Data-driven freeway performance evaluation framework for project prioritization and decision making.

DOT National Transportation Integrated Search

2015-03-01

This report describes methods that potentially can be incorporated into the performance monitoring and planning : processes for freeway performance evaluation and decision making. Reliability analysis is conducted on the selected : I-15 corridor by e...

Investigation of solutions to recurring congestion on freeways.

DOT National Transportation Integrated Search

2009-01-01

Persistent daily congestion, which has been increasing in recent years, is commonly experienced for several hours or more during the morning and evening on Virginia's urban freeways. Many of these roadways are at or near capacity, which causes severe...

Bicycle-Friendly Shoulder Rumble Strips

DOT National Transportation Integrated Search

2000-03-01

Shoulder rumble strips have proven to be an effective way to reduce run-off-the-road (ROR) crashes on urban and rural freeways. As the use of shoulder rumble strips is being extended to non-freeway facilities, bicyclists will encounter rumble strips ...

Trilogy : operational test : final report

DOT National Transportation Integrated Search

1998-09-29

The Trilogy project was an ITS demonstration of the broadcast of freeway system traveler information to both commercial and commuter drivers over a 25-mile (40.3 km) radius of the Twin Cities metropolitan area. In this project, real-time freeway syst...

Investigations of environmental effects on freeway acoustics.

DOT National Transportation Integrated Search

2010-03-01

The study reported here was designed to examine the impact of background meteorological conditions on the : propagation of noise from urban freeways in the Phoenix area. The aim was to understand and predict how : sound waves emanating from highways ...

Design of lane merges at rural freeway construction work zones.

DOT National Transportation Integrated Search

2008-02-01

The goal of this project is to evaluate unconventional lane-drop merge configurations in the vicinity of construction work zones on rural freeways to comparatively assess the conditions of the various designs that impact delay, flow, and safety throu...

Deployment of a tool for measuring freeway safety performance.

DOT National Transportation Integrated Search

2011-12-01

This project updated and deployed a freeway safety performance measurement tool, building upon a previous project that developed the core methodology. The tool evaluates the cumulative risk over time of an accident or a particular kind of accident. T...

Freeway work zone lane capacity.

DOT National Transportation Integrated Search

2009-01-01

The focus of this report is a capacity analysis of two long-term urban freeway Work Zones. Work Zone #1 : tapered four mainline lanes to two, using two separate tapers; Work Zone #2 tapered two mainline lanes to one. : Work Zone throughput was analyz...

Validation of urban freeway models. [supporting datasets

DOT National Transportation Integrated Search

2015-01-01

The goal of the SHRP 2 Project L33 Validation of Urban Freeway Models was to assess and enhance the predictive travel time reliability models developed in the SHRP 2 Project L03, Analytic Procedures for Determining the Impacts of Reliability Mitigati...

Katy Freeway : an evaluation of a second-generation managed lanes project.

DOT National Transportation Integrated Search

2013-04-01

The Katy Freeway Managed Lanes (KML) represents the first operational, multilane managed facility in : Texas and provides an opportunity to benefit from the lessons learned from the project. This study evaluated : multiple aspects of KML and the crit...

Crash location correction for freeway interchange modeling : final report.

DOT National Transportation Integrated Search

2016-06-01

AASHTO released a supplement to the Highway Safety Manual (HSM) in 2014 that includes models for freeway : interchanges composed of segments, speed-change lanes and terminals. A necessary component to the use of HSM is : having the appropriate safety...

Median barrier placement on six-lane, 46-foot median divided freeways

DOT National Transportation Integrated Search

2010-11-01

This report summarizes the research efforts of using finite element modeling and simulations to evaluate the : performance of W-beam guardrails and cable median barriers on six-lane, 46-foot median divided freeways. A : literature review is included ...

Development of incident data collection standards for Virginia Department of Transportation freeway operations.

DOT National Transportation Integrated Search

2005-01-01

The effective management of incidents is necessary in order to maintain efficient freeway operations. Within the Virginia Department of Transportation (VDOT), there are a number of units responsible for supporting incident management. These groups co...

Literature review of methods to determine road user costs in construction zones

DOT National Transportation Integrated Search

1997-01-01

As freeway construction increases with the need to expand, repair and maintain the existing infrastructure, the desire to quantify the inconvenience or delay costs to the user of the freeway undergoing construction has increased and become neccessary...

Evaluation of ground mounted diagrammatic entrance ramp approach signs : final report, October 2000.

DOT National Transportation Integrated Search

2000-10-01

Highway-freeway interchanges can be a source of confusion to unfamiliar drivers. Typically, freeway entrance ramp : information is provided by means of trailblazer assemblies (interstate or highway shield, cardinal direction, and a small : white arro...

Latex allergens in tire dust and airborne particles.

PubMed Central

Miguel, A G; Cass, G R; Weiss, J; Glovsky, M M

1996-01-01

The prevalence and severity of latex allergy has increased dramatically in the last 15 years due to exposure to natural rubber products. Although historically this health risk has been elevated in hospital personnel and patients, a recent survey has indicated a significant potential risk for the general population. To obtain a wide-spread source for latex exposure, we have considered tire debris. We have searched for the presence of latex allergens in passenger car and truck tire tread, in debris deposited from the atmosphere near a freeway, and in airborne particulate matter samples representative of the entire year 1993 at two sites in the Los Angeles basin (California). After extraction of the samples with phosphate buffered saline, a modified-ELISA inhibition assay was used to measure relative allergen potency and Western blot analyses were used to identify latex allergens. The inhibition studies with the human IgE latex assay revealed inhibition by the tire tread source samples and ambient freeway dust, as well as by control latex sap and latex glove extracts. Levels of extractable latex allergen per unit of protein extracted were about two orders of magnitude lower for tire tread as compared to latex gloves. Western blot analyses using binding of human IgE from latex-sensitive patients showed a band at 34-36 kDa in all tire and ambient samples. Long Beach and Los Angeles, California, air samples showed four additional bands between 50 and 135 kDa. Alternative Western blot analyses using rabbit IgG raised against latex proteins showed a broad band at 30-50 kDa in all samples, with additional bands in the urban air samples similar to the IgE results. A latex cross-reactive material was identified in mountain cedar. In conclusion, the latex allergens or latex cross-reactive material present in sedimented and airborne particulate material, derived from tire debris, and generated by heavy urban vehicle traffic could be important factors in producing latex allergy and asthma symptoms associated with air pollution particles. Images Figure 1. Figure 2. A Figure 2. B Figure 3. Figure 4. PMID:8959407

Heavy Metal.

ERIC Educational Resources Information Center

Black, Susan

2001-01-01

The Centers for Disease Control and Prevention (CDC) estimate that more than 1 million children ages 5 and under are afflicted with unsafe amounts of lead. Schools can be a source of lead poisoning. Other sources include playgrounds near freeways, playground equipment, contaminated soil, and technology rooms with lead-bearing supplies. Sidebars…

Evaluating outcomes of raising speed limits on high speed non-freeways.

DOT National Transportation Integrated Search

2015-04-01

The purpose of this research was to assist in determining the potential impacts of implementing a : proposed 65 mph speed limit on non-freeways in Michigan. Consideration was given to a broad range of : performance measures, including operating speed...

HSIS Summary Report: Safety Evaluation of Rolled-in Continuous Shoulder Rumble Strips Installed on Freeways

DOT National Transportation Integrated Search

1999-12-01

This study conducted before and after safety evaluations of projects involving the installation of rolled-in continuous shoulder rumble strips (CSRS) on rural and urban freeways. During resurfacing and shoulder rehabilitation projects, rolled-in CSRS...

Implementation elements for conversion of general-purpose freeway lane into high-occupancy-vehicle lane

DOT National Transportation Integrated Search

1997-01-01

Conversion of a general-purpose freeway into a high-occupancy-vehicle (HOV) lane is an alternative to infrastructure addition for HOV system implementation. Research indicates that lane conversion is feasible technically if sufficient HOV usage and m...

Case studies of the access and mobility impact of freeway removal.

DOT National Transportation Integrated Search

2013-01-01

Throughout the United States, there is a growing movement to remove selected sections of : freeways from city centers. Largely seen as a way to restore life and vitality to these areas, this : strategy has the potential for numerous benefits includin...

An evaluation of the Shirley Highway Express-Bus-on-Freeway Demonstration Project.

DOT National Transportation Integrated Search

1973-01-01

The Shirley Highway Express-Bus-on-Freeway Demonstration Project was initiated to test the hypothesis that the provision of rapid and convenient bus service over an exclusive lane would attract significant numbers of automobile passengers. Such a div...

Freeway performance measurement system : an operational analysis tool

DOT National Transportation Integrated Search

2001-07-30

PeMS is a freeway performance measurement system for all of California. It processes 2 : GB/day of 30-second loop detector data in real time to produce useful information. Managers : at any time can have a uniform, and comprehensive assessment of fre...

Measurements and predictors of on-road ultrafine particle concentrations and associated pollutants in Los Angeles

NASA Astrophysics Data System (ADS)

Fruin, S.; Westerdahl, D.; Sax, T.; Sioutas, C.; Fine, P. M.

Motor vehicles are the dominant source of oxides of nitrogen (NO x), particulate matter (PM), and certain air toxics (e.g., benzene, 1,3-butadiene) in urban areas. On roadways, motor vehicle-related pollutant concentrations are typically many times higher than ambient concentrations. Due to high air exchange rates typical of moving vehicles, this makes time spent in vehicles on roadways a major source of exposure. This paper presents on-road measurements for Los Angeles freeways and arterial roads taken from a zero-emission electric vehicle outfitted with real-time instruments. The objective was to characterize air pollutant concentrations on roadways and identify the factors associated with the highest concentrations. Our analysis demonstrated that on freeways, concentrations of ultrafine particles (UFPs), black carbon, nitric oxide, and PM-bound polycyclic aromatic hydrocarbons (PM-PAH) are generated primarily by diesel-powered vehicles, despite the relatively low fraction (˜6%) of diesel-powered vehicles on Los Angeles freeways. However, UFP concentrations on arterial roads appeared to be driven primarily by proximity to gasoline-powered vehicles undergoing hard accelerations. Concentrations were roughly one-third of those on freeways. By using a multiple regression model for the freeway measurements, we were able to explain 60-70% of the variability in concentrations of UFP, black carbon, nitric oxide, and PM-PAH using measures of diesel truck density and hour of day (as an indicator of wind speed). Freeway concentrations of these pollutants were also well correlated with readily available annual average daily truck counts, potentially allowing improved population exposure estimates for epidemiology studies. Based on these roadway measurements and average driving time, it appears that 33-45% of total UFP exposure for Los Angeles residents occurs due to time spent traveling in vehicles.

Impact of non-freeway rumble strips phase 1 : appendix III, example of rear end "target" crashes.

DOT National Transportation Integrated Search

2012-06-25

In an effort to reduce lane-departure crashes, in 2008 the Michigan Department of Transportation (MDOT) began a three-year statewide non-freeway rumble strip installation initiative. This initiative called for the installation of milled centerline ru...

Investigation of contributing factors regarding wrong-way driving on freeways, phase II.

DOT National Transportation Integrated Search

2015-09-01

In the second phase of this project, two major tasks were completed: (1) organizing a national wrong-way driving : (WWD) summit and (2) developing guidelines for reducing WWD on freeways. The first national WWD summit was : held in Edwardsville, Illi...

Impact of non-freeway rumble strips phase 1 : appendix I, driver behavior data for curve locations.

DOT National Transportation Integrated Search

2012-06-26

In an effort to reduce lane-departure crashes, in 2008 the Michigan Department of Transportation (MDOT) began a three-year statewide non-freeway rumble strip installation initiative. This initiative called for the installation of milled centerline ru...

Understanding Traveler Behavior : The Psychology Behind Managed Lane Use

DOT National Transportation Integrated Search

2012-07-01

Recent analysis of Katy Freeway/Managed Lane (ML) travelers and I-394 Freeway/High : Occupancy Toll (HOT) lane traveler data has found that many travelers pay to use these HOT : lanes and MLs when adjacent toll-free lanes are operating at nearly the ...

Operational Design Guidelines For High Occupancy Vehicle Lanes On Arterial Roadways, Including Planning Strategies And Supporting Measures

DOT National Transportation Integrated Search

1994-11-01

">THIS REPORT IS A COMPANION TO THE 1993 MINISTRY OF TRANSPORTATION OF ONTARIO DOCUMENT, "OPERATION & DESIGN GUIDELINES FOR HOV LANES ON PROVINCIAL FREEWAYS". SINCE THAT DOCUMENT DEALS EXCLUSIVELY AND COMPREHENSIVELY WITH FREEWAY HOV APPLICATIONS, TH...

Continuous freeway illumination and accidents on a section of Rte. I-95.

DOT National Transportation Integrated Search

1978-01-01

Beginning with the oil embargo of 1973-74, highway lighting and particularly continuous lighting on freeways became one of the first items to be cut back to conserve energy and revenue. During this period of energy shortage, considerable lighting was...

Truck accidents at freeway ramps : data analysis and high-risk site identification

DOT National Transportation Integrated Search

1998-01-01

To examine the relationship of ramp design to truck accident rates, this paper presents an analysis of truck accidents in Washington State, plus a comparison to limited data from Colorado and California. The authors group freeway truck accidents by r...

Outsourced probe data effectiveness on signalized arterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharifi, Elham; Young, Stanley Ernest; Eshragh, Sepideh

This paper presents results of an I-95 Corridor Coalition sponsored project to assess the ability of outsourced vehicle probe data to provide accurate travel time on signalized roadways for the purposes of real-time operations as well as performance measures. The quality of outsourced probe data on freeways has led many departments of transportation to consider such data for arterial performance monitoring. From April 2013 through June of 2014, the University of Maryland Center for Advanced Transportation Technology gathered travel times from several arterial corridors within the mid-Atlantic region using Bluetooth traffic monitoring (BTM) equipment, and compared these travel times withmore » the data reported to the I95 Vehicle Probe Project (VPP) from an outsourced probe data vendor. The analysis consisted of several methodologies: (1) a traditional analysis that used precision and bias speed metrics; (2) a slowdown analysis that quantified the percentage of significant traffic disruptions accurately captured in the VPP data; (3) a sampled distribution method that uses overlay methods to enhance and analyze recurring congestion patterns. (4) Last, the BTM and VPP data from each 24-hour period of data collection were reviewed by the research team to assess the extent to which VPP captured the nature of the traffic flow. Based on the analysis, probe data is recommended only on arterial roadways with signal densities (measured in signals per mile) up to one, and it should be tested and used with caution for signal densities between one and two, and is not recommended when signal density exceeds two.« less

San Antonio's Medical Center Corridor: Lessons Learned From The Metropolitan Model Deployment Initiative: Reducing Delay Through Integrated Freeway & Arterial Management

DOT National Transportation Integrated Search

2000-10-01

This report demonstrates the benefits and potential pitfalls of deploying and operating an integrated freeway and arterial management system. In particular, it discusses the lessons learned about the Medical Center Corridor (MCC) Project deployed in ...

Guide for Resurfacing, Restoration and Rehabilitation of Highways and Streets (Other than Freeways)

DOT National Transportation Integrated Search

1995-04-01

The primary purpose of R-R-R projects is to provide a better riding surface, enhance safety, : improve operating conditions, and to preserve and extend the service life of existing non-freeway : facilities. Highway safety is an essential element of R...

Effect of Surface Traffic Count on Taxi Time at Dallas-Fort Worth (DFW) International Airport

NASA Technical Reports Server (NTRS)

Kistler, Matthew Stephen; Gupta, Gautam

2008-01-01

As the amount of air traffic increases over the years, most airports simply do not have the means of expanding to handle the intensified traffic on the surface that will ensue. Precise surveillance equipment and automation concepts, as well as advanced surface traffic algorithms are being developed to improve airport efficiency. These surface algorithms require inputs unique to each airport to ensure maximum efficiency, and minimal taxi delay. This study analyzes surface traffic at Dallas-Fort Worth International Airport (DFW) to determine the effect of the number of aircraft on the surface and the amount of stop and go situations they experience to the amount of additional taxi time encountered. If the surface capacity of an airport is known, minimal delay can be accomplished by limiting the number of taxiing aircraft to that capacity. This concept is related to highways, where traffic flow drastically decreases as more cars occupy the road. An attempt to minimize this effect on highways is seen with the use of metering lights at freeway on-ramps. Since the surface traffic at airports is highly regulated, and aircraft are less mobile on the ground, limiting the surface count to a certain number can greatly reduce the amount of additional taxi time encountered, as well as reduce hazardous emissions. This study will also find the regions of an airport that encounter the most additional taxi time when the number of aircraft in that area is increased. This could help surface traffic algorithms avoid congesting that area, or re-route aircraft to different runways when that area reaches its capacity. The relationship between the amount of stop and go situations an aircraft encounters and their effect on the taxi time of that aircraft will also be investigated. This will help to determine the effect of holding an aircraft on the taxiway as opposed to re-routing it. The lesser of the two should be used when developing surface traffic algorithms to further minimize the delay encountered. The fields investigated in this study include taxi time, the number of aircraft on the surface, the number of stop and go situations, and the time stopped for each aircraft. Taxi time is defined as spot to runway for departures, and runway to spot for arrivals. It does not include ramp area taxi time because the ramp area is controlled differently, and surface traffic schedulers do not currently incorporate them. Taxi time is found by finding the difference between take-off time (OFF) and spot crossing time for departures, and spot crossing time and landing time (ON) for arrivals. All surface data was either found directly using the Surface Operations Data Analysis and Adaptation (SODAA), a tool to analyze the Surface Management System (SMS) generated log files, or indirectly from SODAA using Matlab to derive values from SODAA data. The number of aircraft on the surface is found by looping through the ON times, OFF times, and spot times for each aircraft during a particular day. For each departure aircraft, surface counts are taken at its spot crossing and OFF time. The average of these two is used as the surface count for that aircraft. For arrivals, surface counts are taken at its ON time and its spot crossing time. The average of these two is used.

Water-based condensation particle counters comparison near a major freeway with significant heavy-duty diesel traffic

NASA Astrophysics Data System (ADS)

Lee, Eon S.; Polidori, Andrea; Koch, Michael; Fine, Philip M.; Mehadi, Ahmed; Hammond, Donald; Wright, Jeffery N.; Miguel, Antonio. H.; Ayala, Alberto; Zhu, Yifang

2013-04-01

This study compares the instrumental performance of three TSI water-based condensation particle counter (WCPC) models measuring particle number concentrations in close proximity (15 m) to a major freeway that has a significant level of heavy-duty diesel traffic. The study focuses on examining instrument biases and performance differences by different WCPC models under realistic field operational conditions. Three TSI models (3781, 3783, and 3785) were operated for one month in triplicate (nine units in total) in parallel with two sets of Scanning Mobility Particle Sizer (SMPS) spectrometers for the concurrent measurement of particle size distributions. Inter-model bias under different wind directions were first evaluated using 1-min raw data. Although all three WCPC models agreed well in upwind conditions (lower particle number concentrations, in the range of 103-104 particles cm-3), the three models' responses were significantly different under downwind conditions (higher particle number concentrations, above 104 particles cm-3). In an effort to increase inter-model linear correlations, we evaluated the results of using longer averaging time intervals. An averaging time of at least 15 min was found to achieve R2 values of 0.96 or higher when comparing all three models. Similar results were observed for intra-model comparisons for each of the three models. This strong linear relationship helped identify instrument bias related to particle number concentrations and particle size distributions. The TSI 3783 produced the highest particle counts, followed by TSI 3785, which reported 11% lower during downwind conditions than TSI 3783. TSI 3781 recorded particle number concentrations that were 24% lower than those observed by TSI 3783 during downwind condition. We found that TSI 3781 underestimated particles with a count median diameter less than 45 nm. Although the particle size dependency of instrument performance was found the most significant in TSI 3781, both models 3783 and 3785 showed somewhat size dependency. In addition, within each tested WCPC model, one unit was found to count significantly different and be more sensitive to particle size than the other two. Finally, exponential regression analysis was used to numerically quantify instrumental inter-model bias. Correction equations are proposed to adjust the TSI 3781 and 3785 data to the most recent model TSI 3783.

A simulation study of the impact of the public-private partnership strategy on the performance of transport infrastructure.

PubMed

Huang, Zhengfeng; Zheng, Pengjun; Ma, Yanqiang; Li, Xuan; Xu, Wenjun; Zhu, Wanlu

2016-01-01

The choice of investment strategy has a great impact on the performance of transport infrastructure. Positive projects such as the "Subway plus Property" model in Hong Kong have created sustainable financial profits for the public transport projects. Owing to a series of public debt and other constraints, public-private partnership (PPP) was introduced as an innovative investment model to address this issue and help develop transport infrastructure. Yet, few studies provide a deeper understanding of relationships between PPP strategy and the performance of such transport projects (particularly the whole transport system). This paper defines the research scope as a regional network of freeway. With a popular PPP model, travel demand prediction method, and relevant parameters as input, agents in a simulation framework can simulate the choice of PPP freeway over time. The simulation framework can be used to analyze the relationship between the PPP strategy and performance of the regional freeway network. This study uses the Freeway Network of Yangtze River Delta (FN-YRD) in China as the context. The results demonstrate the value of using simulation models of complex transportation systems to help decision makers choose the right PPP projects. Such a tool is viewed as particularly important given the ongoing transformation of functions of the Chinese transportation sector, including franchise rights of transport projects, and freeway charging mechanism.

Crash prediction method for freeway facilities with high occupancy vehicle (HOV) and high occupancy toll (HOT) lanes.

DOT National Transportation Integrated Search

2015-07-01

This study developed methods for estimating the expected crash frequency of urban freeway segments : with HOV or HOT lanes. The safety impacts of the type of separation between the managed lanes and : general purpose lanes were examined. Separate mod...

Exploration of the SHRP2 naturalistic driving study data to identify factors related to the selection of freeway ramp design speed.

DOT National Transportation Integrated Search

2017-03-01

This research explored the second Strategic Highway Research Program (SHRP2) Naturalistic Driving Study (NDS) database for the potential to identify freeway entrance and exit ramps and teen drivers behavior while traveling those ramps. This is in ...

Freeway roadside management: the urban forest beyond the white line

Treesearch

Kathleen Wolf

2003-01-01

A national survey was conducted in the United States to learn more about public preferences and perceptions regarding forest and vegetation planning and management in urban freeway roadsides. In response to images depicting a visual continuum of landscape management treatments, drivers most preferred settings having tree plantings that...

Performance of Original and Resurfaced Pavements in the Illinois Freeway System

DOT National Transportation Integrated Search

1997-02-01

In previous studies, the performance of bare and resurfaced JRCP and CRCP on the Illinois freeway system was assessed by survival analyses. In this study, the 1994 data has been used to update the survival analysis of JRCP and CRCP and to carry out a...

What have we learned about intelligent transportation systems? Chapter 2, What have we learned about freeway incident and emergency management and electronic toll collection?

DOT National Transportation Integrated Search

2000-12-01

The intelligent infrastructure is often the most visible manifestation of intelligent transportation systems (ITS) along with roads, freeways, and incident management is often among the first ITS elements implemented. They can significantly contribut...

Impact of non-freeway rumble strips phase 1 : appendix II, example of run off the road left "target" crashes.

DOT National Transportation Integrated Search

2012-06-26

In an effort to reduce lane-departure crashes, in 2008 the Michigan Department of Transportation (MDOT) began a three-year statewide non-freeway rumble strip installation initiative. This initiative called for the installation of milled centerline ru...

Using Quasi-Horizontal Alignment in the absence of the actual alignment.

PubMed

Banihashemi, Mohamadreza

2016-10-01

Horizontal alignment is a major roadway characteristic used in safety and operational evaluations of many facility types. The Highway Safety Manual (HSM) uses this characteristic in crash prediction models for rural two-lane highways, freeway segments, and freeway ramps/C-D roads. Traffic simulation models use this characteristic in their processes on almost all types of facilities. However, a good portion of roadway databases do not include horizontal alignment data; instead, many contain point coordinate data along the roadways. SHRP 2 Roadway Information Database (RID) is a good example of this type of data. Only about 5% of this geodatabase contains alignment information and for the rest, point data can easily be produced. Even though the point data can be used to extract actual horizontal alignment data but, extracting horizontal alignment is a cumbersome and costly process, especially for a database of miles and miles of highways. This research introduces a so called "Quasi-Horizontal Alignment" that can be produced easily and automatically from point coordinate data and can be used in the safety and operational evaluations of highways. SHRP 2 RID for rural two-lane highways in Washington State is used in this study. This paper presents a process through which Quasi-Horizontal Alignments are produced from point coordinates along highways by using spreadsheet software such as MS EXCEL. It is shown that the safety and operational evaluations of the highways with Quasi-Horizontal Alignments are almost identical to the ones with the actual alignments. In the absence of actual alignment the Quasi-Horizontal Alignment can easily be produced from any type of databases that contain highway coordinates such geodatabases and digital maps. Copyright © 2016 Elsevier Ltd. All rights reserved.

Particulate Matter Concentrations in East Oakland's High Street Corridor

NASA Astrophysics Data System (ADS)

Lei, P.; Jackson, J.; Lewis, R.; Marigny, A.; Mitchell, J. D.; Nguyen, R.; Philips, B.; Randle, D.; Romero, D.; Spears, D.; Telles, C.; Weissman, D.

2012-12-01

Particulate matter (PM) is a complex mixture of small solid pieces and/or liquid droplets in the air. High concentrations of PM can pose a serious health hazard because inhalation can result in breathing problems and/or aggravate asthma. Long term exposure can increase the likelihood of respiratory problems like asthma and emphysema as well as cancer. The smaller the particles, the deeper they can get into the respiratory system. For this reason, the smallest particles, those smaller than 2.5 micrometers in diameter (PM2.5), are the most dangerous. PM2.5 is largely emitted from motor vehicles burning fuels that don't break down fully. Our research team investigated the levels of PM2.5 as well as particles smaller than 10 micrometers (PM10) and total suspended particulate (TSP) along the northeast-southwest trending High Street Corridor, near Fremont High School in East Oakland, California. Using the Aerocet 531 mass particle counter, team members walked through neighborhoods and along major roads within a 1 mile radius of Fremont High School. The Aerocet 531 recorded two minute average measurements of all the relevant PM sizes, which are reported in mg/m3. Measurements were consistently taken in the morning, between 8:30 and 11:30 am. Preliminary results indicate maximum readings of all PM sizes at sites that are in close proximity to a major freeway (Interstate-880). These results support our initial hypothesis that proximity to major roads and freeways, especially those with high diesel-fuel burning truck traffic, would be the primary factor affecting PM concentration levels. Preliminary median and maximum readings all suggest particulate matter levels below what the EPA would consider unhealthy or risky.

Near-Roadway Emission of Reactive Nitrogen Compounds and Other Non-Criteria Pollutants at a Southern California Freeway Site

NASA Astrophysics Data System (ADS)

Moss, J. A.; Baum, M.; Castonguay, A. E.; Aguirre, V., Jr.; Pesta, A.; Fanter, R. K.; Anderson, M.

2015-12-01

Emission control systems in light-duty motor vehicles (LDMVs) have played an important role in improving regional air quality by dramatically reducing the concentration of criteria pollutants (carbon monoxide, hydrocarbons, and nitrogen oxides) in exhaust emissions. Unintended side-reactions occurring on the surface of three-way catalysts may lead to emission of a number of non-criteria pollutants whose identity and emission rates are poorly understood. A series of near-roadway field studies conducted between 2009-2015 has investigated LDMV emissions of these pollutants with unprecedented depth of coverage, including reactive nitrogen compounds (NH3, amines, HCN, HONO, and HNO3), organic peroxides, and carbonyl compounds (aldehydes, ketones, and carboxylic acids). Methods to collect these pollutants using mist chambers, annular denuders, impingers, and solid-phase cartridges and quantify their concentration using GC-MS, LC-MS/MS, IC, and colorimetry were developed and validated in the laboratory and field. These methods were subsequently used in near-roadway field studies where the concentrations of the target compounds integrated over 1-4 hour blocks were measured at the edge of a freeway and at a background site 140 m from the roadway. Concentrations followed a steep decreasing gradient from the freeway to the background site. Emission factors (pollutant mass emitted per mass fuel consumed) were calculated by carbon mass balance using the difference in concentration measured between the freeway and background sites for the emitted pollutant and CO2 as a measure of carbon mass in the vehicle exhaust. The significance of these results will be discussed in terms of emissions inventories in the South Coast Air Basin of California, emission trends at this site over the period of 2009-2015, and for NH3, emission measurements conducted by our group and others over the period 2000-2015.

Algorithm design, user interface, and optimization procedure for a fuzzy logic ramp metering algorithm : a training manual for freeway operations engineers

DOT National Transportation Integrated Search

2000-02-01

This training manual describes the fuzzy logic ramp metering algorithm in detail, as implemented system-wide in the greater Seattle area. The method of defining the inputs to the controller and optimizing the performance of the algorithm is explained...

Characterization of air pollutant concentrations, fleet emission factors, and dispersion near a North Carolina interstate freeway across two seasons

NASA Astrophysics Data System (ADS)

Saha, Provat K.; Khlystov, Andrey; Snyder, Michelle G.; Grieshop, Andrew P.

2018-03-01

We present field measurement data and modeling of multiple traffic-related air pollutants during two seasons at a site adjoining Interstate 40, near Durham, North Carolina. We analyze spatial-temporal and seasonal trends and fleet-average pollutant emission factors and use our data to evaluate a line source dispersion model. Month-long measurement campaigns were performed in summer 2015 and winter 2016. Data were collected at a fixed near-road site located within 10 m from the highway edge, an upwind background site and, under favorable meteorological conditions, along downwind perpendicular transects. Measurements included the size distribution, chemical composition, and volatility of submicron particles, black carbon (BC), nitrogen oxides (NOx), meteorological conditions and traffic activity data. Results show strong seasonal and diurnal differences in spatial distribution of traffic sourced pollutants. A strong signature of vehicle emissions was observed within 100-150 m from the highway edge with significantly higher concentrations during morning. Substantially higher concentrations and less-sharp near-road gradients were observed in winter for many species. Season-specific fleet-average fuel-based emission factors for NO, NOx, BC, and particle number (PN) were derived based on up- and down-wind roadside measurements. The campaign-average NOx and PN emission factors were 20% and 300% higher in winter than summer, respectively. These results suggest that the combined effect of higher emissions and their slower downwind dispersion in winter dictate the observed higher downwind concentrations and wider highway influence zone in winter for several species. Finally, measurements of traffic data, emission factors, and pollutant concentrations were integrated to evaluate a line source dispersion model (R-LINE). The dispersion model captured the general trends in the spatial and temporal patterns in near-road concentrations. However, there was a tendency for the model to under-predict concentrations near the road in the mornings and over-predict concentrations in the evenings.

Did mud contribute to freeway collapse?

NASA Astrophysics Data System (ADS)

Hough, Susan E.; Friberg, Paul A.; Busby, Robert; Field, Edward F.; Jacob, Klaus H.; Borcherdt, Roger D.

At least 41 people were killed October 17 when the upper tier of the Nimitz Freeway in Oakland, Calif., collapsed during the Ms = 7.1 Loma Prieta earthquake. Seismologists studying aftershocks concluded that soil conditions and resulting ground motion amplification were important in the failure of the structure and should be considered in the reconstruction of the highway.Structural design weaknesses in the two-tiered freeway, known as the Cypress structure, had been identified before the tragedy. The seismologists, from Lamont Doherty Geological Observatory in Palisades, N.Y., and the U.S. Geological Survey in Menlo Park, Calif., found that the collapsed section was built on fill over Bay mud. A southern section of the Cypress structure built on alluvium of Quaternary age did not collapse (see Figure 1).

A generalized exponential link function to map a conflict indicator into severity index within safety continuum framework.

PubMed

Zheng, Lai; Ismail, Karim

2017-05-01

Traffic conflict indicators measure the temporal and spatial proximity of conflict-involved road users. These indicators can reflect the severity of traffic conflicts to a reliable extent. Instead of using the indicator value directly as a severity index, many link functions have been developed to map the conflict indicator to a severity index. However, little information is available about the choice of a particular link function. To guard against link misspecification or subjectivity, a generalized exponential link function was developed. The severity index generated by this link was introduced to a parametric safety continuum model which objectively models the centre and tail regions. An empirical method, together with full Bayesian estimation method was adopted to estimate model parameters. The safety implication of return level was calculated based on the model parameters. The proposed approach was applied to the conflict and crash data collected from 21 segments from three freeways located in Guangdong province, China. The Pearson's correlation test between return levels and observed crashes showed that a θ value of 1.2 was the best choice of the generalized parameter for current data set. This provides statistical support for using the generalized exponential link function. With the determined generalized exponential link function, the visualization of parametric safety continuum was found to be a gyroscope-shaped hierarchy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Prenatal air pollution exposure and ultrasound measures of fetal growth in Los Angeles, California.

PubMed

Ritz, Beate; Qiu, Jiaheng; Lee, Pei-Chen; Lurmann, Fred; Penfold, Bryan; Erin Weiss, Robert; McConnell, Rob; Arora, Chander; Hobel, Calvin; Wilhelm, Michelle

2014-04-01

Few previous studies examined the impact of prenatal air pollution exposures on fetal development based on ultrasound measures during pregnancy. In a prospective birth cohort of more than 500 women followed during 1993-1996 in Los Angeles, California, we examined how air pollution impacts fetal growth during pregnancy. Exposure to traffic related air pollution was estimated using CALINE4 air dispersion modeling for nitrogen oxides (NOx) and a land use regression (LUR) model for nitrogen monoxide (NO), nitrogen dioxide (NO2) and NOx. Exposures to carbon monoxide (CO), NO2, ozone (O3) and particles <10μm in aerodynamic diameter (PM10) were estimated using government monitoring data. We employed a linear mixed effects model to estimate changes in fetal size at approximately 19, 29 and 37 weeks gestation based on ultrasound. Exposure to traffic-derived air pollution during 29 to 37 weeks was negatively associated with biparietal diameter at 37 weeks gestation. For each interquartile range (IQR) increase in LUR-based estimates of NO, NO2 and NOx, or freeway CALINE4 NOx we estimated a reduction in biparietal diameter of 0.2-0.3mm. For women residing within 5km of a monitoring station, we estimated biparietal diameter reductions of 0.9-1.0mm per IQR increase in CO and NO2. Effect estimates were robust to adjustment for a number of potential confounders. We did not observe consistent patterns for other growth endpoints we examined. Prenatal exposure to traffic-derived pollution was negatively associated with fetal head size measured as biparietal diameter in late pregnancy. Copyright © 2014 Elsevier Inc. All rights reserved.

Prenatal Air Pollution Exposure and Ultrasound Measures of Fetal Growth in Los Angeles, California

PubMed Central

Ritz, Beate; Qiu, Jiaheng; Lee, Pei-Chen; Lurmann, Fred; Penfold, Bryan; Weiss, Robert Erin; McConnell, Rob; Arora, Chander; Hobel, Calvin; Wilhelm, Michelle

2014-01-01

Background Few previous studies examined the impact of prenatal air pollution exposures on fetal development based on ultrasound measures during pregnancy. Methods In a prospective birth cohort of more than 500 women followed during 1993-1996 in Los Angeles, California, we examined how air pollution impacts fetal growth during pregnancy. Exposure to traffic related air pollution was estimated using CALINE4 air dispersion modeling for nitrogen oxides (NOx) and a land use regression (LUR) model for nitrogen monoxide (NO), nitrogen dioxide (NO2) and NOx. Exposures to carbon monoxide (CO), NO2, ozone (O3) and particles <10 μm in aerodynamic diameter (PM10) were estimated using government monitoring data. We employed a linear mixed effects model to estimate changes in fetal size at approximately 19, 29 and 37 weeks gestation based on ultrasound. Results Exposure to traffic-derived air pollution during 29 to 37 weeks was negatively associated with biparietal diameter at 37 weeks gestation. For each interquartile range (IQR) increase in LUR-based estimates of NO, NO2 and NOx, or freeway CALINE4 NOx we estimated a reduction in biparietal diameter of 0.2-0.3 mm. For women residing within 5 km of a monitoring station, we estimated biparietal diameter reductions of 0.9-1.0 mm per IQR increase in CO and NO2. Effect estimates were robust to adjustment for a number of potential confounders. We did not observe consistent patterns for other growth endpoints we examined. Conclusions Prenatal exposure to traffic-derived pollution was negatively associated with fetal head size measured as biparietal diameter in late pregnancy. PMID:24517884

Design of Dual-Road Transportable Portal Monitoring System for Visible Light and Gamma-Ray Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karnowski, Thomas Paul; Cunningham, Mark F; Goddard Jr, James Samuel

2010-01-01

The use of radiation sensors as portal monitors is increasing due to heightened concerns over the smuggling of fissile material. Transportable systems that can detect significant quantities of fissile material that might be present in vehicular traffic are of particular interest, especially if they can be rapidly deployed to different locations. To serve this application, we have constructed a rapid-deployment portal monitor that uses visible-light and gamma-ray imaging to allow simultaneous monitoring of multiple lanes of traffic from the side of a roadway. The system operation uses machine vision methods on the visible-light images to detect vehicles as they entermore » and exit the field of view and to measure their position in each frame. The visible-light and gamma-ray cameras are synchronized which allows the gamma-ray imager to harvest gamma-ray data specific to each vehicle, integrating its radiation signature for the entire time that it is in the field of view. Thus our system creates vehicle-specific radiation signatures and avoids source confusion problems that plague non-imaging approaches to the same problem. Our current prototype instrument was designed for measurement of upto five lanes of freeway traffic with a pair of instruments, one on either side of the roadway. Stereoscopic cameras are used with a third alignment camera for motion compensation and are mounted on a 50 deployable mast. In this paper we discuss the design considerations for the machine-vision system, the algorithms used for vehicle detection and position estimates, and the overall architecture of the system. We also discuss system calibration for rapid deployment. We conclude with notes on preliminary performance and deployment.« less

Design of dual-road transportable portal monitoring system for visible light and gamma-ray imaging

NASA Astrophysics Data System (ADS)

Karnowski, Thomas P.; Cunningham, Mark F.; Goddard, James S.; Cheriyadat, Anil M.; Hornback, Donald E.; Fabris, Lorenzo; Kerekes, Ryan A.; Ziock, Klaus-Peter; Bradley, E. Craig; Chesser, J.; Marchant, W.

2010-04-01

The use of radiation sensors as portal monitors is increasing due to heightened concerns over the smuggling of fissile material. Transportable systems that can detect significant quantities of fissile material that might be present in vehicular traffic are of particular interest, especially if they can be rapidly deployed to different locations. To serve this application, we have constructed a rapid-deployment portal monitor that uses visible-light and gamma-ray imaging to allow simultaneous monitoring of multiple lanes of traffic from the side of a roadway. The system operation uses machine vision methods on the visible-light images to detect vehicles as they enter and exit the field of view and to measure their position in each frame. The visible-light and gamma-ray cameras are synchronized which allows the gamma-ray imager to harvest gamma-ray data specific to each vehicle, integrating its radiation signature for the entire time that it is in the field of view. Thus our system creates vehicle-specific radiation signatures and avoids source confusion problems that plague non-imaging approaches to the same problem. Our current prototype instrument was designed for measurement of upto five lanes of freeway traffic with a pair of instruments, one on either side of the roadway. Stereoscopic cameras are used with a third "alignment" camera for motion compensation and are mounted on a 50' deployable mast. In this paper we discuss the design considerations for the machine-vision system, the algorithms used for vehicle detection and position estimates, and the overall architecture of the system. We also discuss system calibration for rapid deployment. We conclude with notes on preliminary performance and deployment.

40 CFR 93.101 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

...(c)(2)(A), 182(c)(2)(B), 187(a)(7), 187(g), 189(a)(1)(B), 189(b)(1)(A), and 189(d); sections 192(a... project, e.g., freeway, expressway, arterial highway, grade-separated highway, reserved right-of-way rail... person carrying capacity and control, e.g., number of lanes or tracks to be constructed or added, length...

Learning in the Fast Lane: The Freeway Game

ERIC Educational Resources Information Center

Giraud-Carrier, François C.; Schmidt, Glen M.

2015-01-01

When deciding whether to get on the freeway during rush hour, did you ever stop to consider that if you did so, you would slow everybody ELSE down? When we ask our students that question, they typically laugh--their only consideration is how long their own trip will take. When a decision maker does not account for all the costs or benefits…

Dallas Freeway/HOV system planning study: Year 2015. A summary of recommended hov improvements. Interim research report, September 1992-August 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walters, C.H.; Lomax, T.J.; Poe, C.M.

1995-07-01

The Dallas Freeway/High-Occupany Vehicle Lane System Planning Study is a joint project in cooperation with the Texas Department of Transportation (TxDOT), Dallas Area Rapid Transit (DART), the North Central Texas Council of Governments (NCTCOG), and the Texas Transportation Institute (TTI). The intent of this effort is to assist in the development of an area-wide freeway/HOV system that recognizes implementation constraints (right-of-way and construction costs) and provides reasonable peak-hour operating conditions on all freeway facilities, while incorporating the long-range plans developed by TxDOT, DART, and NCTCOG. The proposed system is a set of recommendations to be considered and evaluated as partmore » of the development of the NCTCOG Mobility 2010 Plan Update, the long-range transportation plan for the Dallas area. HOV facilities are a significant part of the recommended system in the Dallas System Planning Study, and their implementation is important to the successful operation of the Dallas area transportation system in the future. The report, therefore, focuses on the recommended HOV improvements from the methodology.« less

Combined effects of compact cevelopment, transportation investments, and road user pricing on vehicle miles traveled in urbanized areas

USGS Publications Warehouse

Ewing, Reid; Hamidi, Shima; Gallivan, Frank; Nelson, Arthur C.; Grace, James B.

2014-01-01

Vehicle miles traveled (VMT) is the primary determinant of traffic congestion, vehicle crashes, greenhouse gas emissions, and other effects of transportation. Two previous studies have sought to explain VMT levels in urbanized areas. This study updates and expands on previous work with more recent data, additional metrics, and structural equation modeling (SEM) to explain VMT levels in 315 urbanized areas. According to SEM, population, income, and gasoline prices are primary exogenous drivers of VMT. Development density is a primary endogenous driver. Urbanized areas with more freeway capacity are significantly less dense and have significantly higher VMT per capita. Areas with more transit service coverage and service frequency have higher development densities and per capita transit use, which leads to lower VMT per capita. The indirect effect of transit on VMT through land use, the so-called land use multiplier, is more than three times greater than the direct effect through transit ridership.

Emission rates of regulated pollutants from on-road heavy-duty diesel vehicles

NASA Astrophysics Data System (ADS)

Shah, Sandip D.; Johnson, Kent C.; Wayne Miller, J.; Cocker, David R.

Emissions from heavy-duty diesel (HDD) vehicles are affected by many factors. Changes in engine technology, operating mode, fuel properties, vehicle speed and ambient conditions can have significant effects on emission rates of regulated species. This paper presents the results of on-road emissions testing of 11 HDD vehicles (model years 1996-2000) over the ARB Four Phase driving schedule and the urban dynamometer driving schedule (UDDS). Emission rates were found to be highly dependent on vehicle operating mode. Per mile NO x emission rates for vehicle operation at low speeds, in simulated congested traffic, were three times higher per mile emissions then while cruising on the freeway. Comparisons of NO x emission factors to EMFAC baseline emission factors were within 5-40% for vehicles of various model years tested over the UDDS. A comparison of NO x emission factors for a weighted average of the ARB four phase driving schedule yielded values within 17-57% of EMFAC values. Generally, particulate matter (PM) emission rates were lower than EMFAC values.

Topography as a contextual variable in infectious disease transmission.

PubMed

Montoya, Isaac D

2004-01-01

This paper examines whether or not topography is a contextual variable that indirectly influences the transmission of infectious diseases. Age, gender, race/ethnicity, education level, economic status, injection drug use, and high-risk sexual behavior are known to influence infectious diseases transmission, but the effects of topography are often overlooked. A sample of 395 drug users were chosen from census tracts based upon a target profile of drug use behavior and demographics for the city of Houston. HIV was chosen as the infectious disease used to test this hypothesis. Residents of 16 census tracts in Houston, Texas participated in this study. The findings revealed that census tracts that were 'isolated' by topographic barriers, such as bayous, parks, railroad tracks, railway yards, major thoroughfares, freeways, and unique street grids had fewer cases of HIV than census tracks that were more accessible to thru-traffic. The research findings suggest that future research studies should consider topography as being contextually related to infectious disease transmission.

Joint measurements of black carbon and particle mass for ...

EPA Pesticide Factsheets

The black carbon (BC) emitted from heavy-duty diesel vehicles(HDDVs) is an important source of urban atmospheric pollution and createsstrong climate-forcing impacts. The emission ratio of BC to totalparticle mass (PM) (i.e., BC/PM ratio) is an essential variable used toestimate total BC emissions from historical PM data; however, theseratios have not been measured using portable emission measurement systems(PEMS) in order to obtain real-world measurements over a wide range ofdriving conditions. In this study, we developed a PEMS platform byintegrating two Aethalometers and an electric low pressure impactor torealize the joint measurement of real-world BC and PM emissions for tenHDDVs in China. Test results showed that the average BC/PM ratio for fiveHDDVs equipped with mechanical fuel injection (MI) engines was 0.43±0.06,significantly lower (P<0.05) than another five HDDVs equipped withelectronically-controlled fuel injection (EI) engines (0.56±0.12).Traffic conditions also affected the BC/PM ratios with higher BC/PMratios on freeway routes than on local roads. Further, higher ratios wereobserved for HDDVs equipped with EI engines than for the MI engines forthe highway and local road routes. With an operating mode binningapproach, we observed that the instantaneous BC/PM ratios of EI enginevehicles were above those of the MI engine vehicles in all operatingmodes except for the braking mode (i.e., Bin 0). Therefore, the compleximpacts from engine technology and

75 FR 5168 - Notice of Final Federal Agency Action on Proposed Highway in Illinois

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-01

... limitation on claims for judicial review of actions by FHWA and other Federal agencies. SUMMARY: This notice... construction of an access-controlled, four-lane freeway on new right-of-way between the existing IL 6... final agency actions subject to 23 U.S.C. 139(l)(1). A claim seeking judicial review of the Federal...

Chapter C. The Loma Prieta, California, Earthquake of October 17, 1989 - Fire, Police, Transportation and Hazardous Materials

USGS Publications Warehouse

Van Anne, Craig; Scawthorn, Charles R.

1994-01-01

The papers in this chapter discuss some of the failures and successes that resulted from the societal response by a multitude of agencies to the Loma Prieta earthquake. Some of the lessons learned were old ones relearned. Other lessons were obvious ones which had gone unnoticed. Still, knowledge gained from past earthquakes spawned planning and mitigation efforts which proved to be successful in limiting the aftermath effects of the Loma Prieta event. At least four major areas of response are presented in this chapter: the Oakland Police Department response to the challenge of controlled access to the Cypress freeway collapse area without inhibiting relief and recovery efforts; search and rescue of the freeway collapse and the monumental crisis management problem that accompanied it; the short- and long-term impact on transbay transportation systems to move a large work force from home to business; and the handling of hazardous material releases throughout the Bay Area.

Driver distraction in an unusual environment: Effects of text-messaging in tunnels.

PubMed

Rudin-Brown, Christina M; Young, Kristie L; Patten, Christopher; Lenné, Michael G; Ceci, Ruggero

2013-01-01

Text messaging while driving can be distracting and significantly increases the risk of being involved in a collision. Compared to freeway driving, driving in a tunnel environment introduces factors that may interact with driver attentional resources to exacerbate the effects of distraction on driving safety. With planning and design of the 18km Stockholm Bypass tunnel ongoing, and because of the potentially devastating consequences of crashes in long tunnels, it is critical to assess the effects of driver distraction in a tunnel environment. Twenty-four participants (25-50 years) drove in simulated highway and tunnel road environments while reading and writing text messages using their own mobile phones. As expected, compared to driving alone, text messaging was associated with decrements in driving performance and visual scanning behavior, and increases in subjective workload. Speeds were slower compared to baseline (no text-messaging) driving when participants performed the text-messaging tasks in the tunnel environment compared to the freeway, suggesting that drivers may have attempted to compensate more for the increased text-messaging-related workload when they were in the tunnel. On the other hand, increases in lane deviation associated with the most complex text-messaging task were more pronounced in the tunnel compared to on the freeway. Collectively, results imply that driver distraction in tunnels is associated with generally similar driving decrements as freeway driving; however, the potential consequences of these decrements in tunnels remain significantly more serious. Future research should attempt to elucidate the nature of any differential compensatory behavior in tunnel, compared to freeway, driving. In the meantime, drivers should be advised to refrain from text messaging, especially when driving in tunnels. Copyright © 2012 Elsevier Ltd. All rights reserved.

Advanced control architecture for autonomous vehicles

NASA Astrophysics Data System (ADS)

Maurer, Markus; Dickmanns, Ernst D.

1997-06-01

An advanced control architecture for autonomous vehicles is presented. The hierarchical architecture consists of four levels: a vehicle level, a control level, a rule-based level and a knowledge-based level. A special focus is on forms of internal representation, which have to be chosen adequately for each level. The control scheme is applied to VaMP, a Mercedes passenger car which autonomously performs missions on German freeways. VaMP perceives the environment with its sense of vision and conventional sensors. It controls its actuators for locomotion and attention focusing. Modules for perception, cognition and action are discussed.

Dynamic analysis of a long span, cable-stayed freeway bridge using NASTRAN

NASA Technical Reports Server (NTRS)

Salus, W. L.; Jones, R. E.; Ice, M. W.

1973-01-01

The dynamic analysis for earthquake- and wind-induced response of a long span, cable-stayed freeway bridge by NASTRAN in conjunction with post-processors is described. Details of the structural modeling, the input data generation, and numerical results are given. The influence of the dynamic analysis on the bridge design is traced from the project initiation to the development of a successful earthquake and wind resistant configuration.

Seat-belt wearing and driving behavior: an instrumented-vehicle study.

PubMed

Janssen, W

1994-04-01

Less-than-expected fatality reductions after seat-belt legislation has been introduced in a jurisdiction may be explained in terms of selective recruitment of parts of the driving population and/or behavioral adaptation by beginning belt users. The present investigation has compared the relative merits of these two hypotheses at the level of individual driver behavior. In the initial study the driving behavior of groups of habitual wearers and nonwearers of the belt was compared. Nonwearers made two trips, one with the belt on and one without the belt. Habitual wearers drove belted only. The main part of the experiment was a 105 km freeway route. Two additional tasks of a somewhat more critical nature, a double lane-change manoeuvre and the performance of a braking manoeuvre in front of a fixed obstacle, were performed after the freeway trips. Factor analysis on 39 variables describing driving behavior on the road and during the additional tasks resulted in five factors. One of these, the factor describing the distribution of driving speed on the freeway, differentiated between nonwearers and wearers (thus yielding support for the selective recruitment hypothesis) as well as between wearing and not wearing the belt by the same drivers (thus yielding support for the behavioral adaptation hypothesis). In the follow-up study the original wearers and nonwearers were assigned to one of four experimental treatments: (i) the promise by the experimenter of a considerable incentive for not having a culpable motor vehicle accident over a period of a year. Half the habitual wearer subjects were assigned to this condition. The expectation was that this group would become more careful in their driving; (ii) a control group, consisting of the remaining habitual wearers; (iii) the agreement between the experimenter and the subject that the latter would buckle up in everyday driving for the year to come--half the habitual nonwearer subjects were assigned to this condition; (iv) a control group to the previous treatment, consisting of the remaining habitual nonwearers. All subjects returned for repeat measurements, consisting of the freeway trips plus additional tasks, three times over the next year. The main result was that beginning wearers (group iii) showed signs of continuing behavioral adaptation, in the form of increased speed and increased propensity for close following, as well as several minor effects. The "incentive" group (group i), however, did not change driving behavior in the expected sense, i.e. in the safe direction.

Intelligent Traffic Light Based on PLC Control

NASA Astrophysics Data System (ADS)

Mei, Lin; Zhang, Lijian; Wang, Lingling

2017-11-01

The traditional traffic light system with a fixed control mode and single control function is contradicted with the current traffic section. The traditional one has been unable to meet the functional requirements of the existing flexible traffic control system. This paper research and develop an intelligent traffic light called PLC control system. It uses PLC as control core, using a sensor module for receiving real-time information of vehicles, traffic control mode for information to select the traffic lights. Of which control mode is flexible and changeable, and it also set the countdown reminder to improve the effectiveness of traffic lights, which can realize the goal of intelligent traffic diversion, intelligent traffic diversion.

Evaluating the impacts of grades on vehicular speeds on interstate highways.

PubMed

Chen, Xinqiang; Li, Zhibin; Wang, Yinhai; Cui, Zhiyong; Shi, Chaojian; Wu, Huafeng

2017-01-01

Grade variation on interstate highways affects the roadway geometric design, vehicle performance and driver behavior, thus possibly exerting an unexpected effect on vehicular speed. Hence, determining the internal relationship between grade and speed is important and useful for drivers, traffic regulators and other traffic participants. However, the problem with performing this research is the lack of large-scale gradient and speed data. Google Earth (GE) provides an application programming interface for extracting elevation data worldwide. The elevation dataset from GE can be easily converted to grade data. In addition, our team has collected and stored speed series data for different freeways over several years. Based on the above obtainable grade and speed datasets, we conducted research on the effect of grades on free flow speeds from two perspectives. First, the influence of grades on speed was analyzed from both quantitative and qualitative aspects. The analysis of the distributions of four typical types of speeds demonstrated a decreasing tendency as the speed increased. Steeper grades generated a more intense speed fluctuation in terms of the four types of speeds. Second, a model based on the Student's t-test was developed to evaluate the level of significant difference among speed series under neighboring grades. The Student's t-test demonstrated that adjacent grades do not significantly influence the speeds. In summary, speeds under different grades showed obviously different tendencies. The findings of this study can help transport authorities set more reasonable speed limits and improve the geometric design of interstates with grade variation constraints.

Impact of pavement conditions on crash severity.

PubMed

Li, Yingfeng; Liu, Chunxiao; Ding, Liang

2013-10-01

Pavement condition has been known as a key factor related to ride quality, but it is less clear how exactly pavement conditions are related to traffic crashes. The researchers used Geographic Information System (GIS) to link Texas Department of Transportation (TxDOT) Crash Record Information System (CRIS) data and Pavement Management Information System (PMIS) data, which provided an opportunity to examine the impact of pavement conditions on traffic crashes in depth. The study analyzed the correlation between several key pavement condition ratings or scores and crash severity based on a large number of crashes in Texas between 2008 and 2009. The results in general suggested that poor pavement condition scores and ratings were associated with proportionally more severe crashes, but very poor pavement conditions were actually associated with less severe crashes. Very good pavement conditions might induce speeding behaviors and therefore could have caused more severe crashes, especially on non-freeway arterials and during favorable driving conditions. In addition, the results showed that the effects of pavement conditions on crash severity were more evident for passenger vehicles than for commercial vehicles. These results provide insights on how pavement conditions may have contributed to crashes, which may be valuable for safety improvement during pavement design and maintenance. Readers should notice that, although the study found statistically significant effects of pavement variables on crash severity, the effects were rather minor in reality as suggested by frequency analyses. Copyright © 2013 Elsevier Ltd. All rights reserved.

Scanning secondary derived crashes from disabled and abandoned vehicle incidents on uninterrupted flow highways.

PubMed

Chimba, Deo; Kutela, Boniphace

2014-09-01

Extent of secondary crashes derived from primary incidents involving abandoned and disabled vehicles are presented in this paper. Using years 2004 to 2010 incident and crash data on selected Tennessee freeways, the study identified secondary crashes that resulted from disabled and abandoned vehicle primary incidents. The relationship between time and distance gaps before the secondary crash with respect to individual incident characteristics were evaluated through descriptive statistics and linear regression. The time and distance gap analysis indicated that a large portion of secondary crashes occurred within 20 min after the primary incidents and within a distance of 0.5 miles upstream. While 76% of incidents involved shoulder, most secondary crashes were related to the closing of right lanes. Overall, 58% of the secondary crashes occurred within 30 min after the occurrence of the primary incidents. Most of the vehicles in the incidents that involved towing and caused secondary crashes were towed or removed out of the travel way within 60 min from the time of occurrence. The study found that most (95%) secondary crashes were property damage only (PDO), while 49% were rear-end crashes. The negative binomial model was used to evaluate the impact of roadway geometry and traffic factors associated with frequency of these secondary crashes. It was found that the posted speed limit, congested segments, segments with high percentages of trucks, and peak hour volumes increased the likelihood of secondary crash occurrence. Roadway segments with wider medians, shoulders, and multilanes decrease the likelihood of secondary crashes caused by abandoned and disabled vehicles as the primary incidents. Practical applications The paper recommends that wider shoulders be provided on any section of freeway to accommodate abandoned or disabled vehicles to avoid blocking of travel lane(s). Copyright © 2014 National Safety Council and Elsevier Ltd. All rights reserved.

A Sarsa(λ)-based control model for real-time traffic light coordination.

PubMed

Zhou, Xiaoke; Zhu, Fei; Liu, Quan; Fu, Yuchen; Huang, Wei

2014-01-01

Traffic problems often occur due to the traffic demands by the outnumbered vehicles on road. Maximizing traffic flow and minimizing the average waiting time are the goals of intelligent traffic control. Each junction wants to get larger traffic flow. During the course, junctions form a policy of coordination as well as constraints for adjacent junctions to maximize their own interests. A good traffic signal timing policy is helpful to solve the problem. However, as there are so many factors that can affect the traffic control model, it is difficult to find the optimal solution. The disability of traffic light controllers to learn from past experiences caused them to be unable to adaptively fit dynamic changes of traffic flow. Considering dynamic characteristics of the actual traffic environment, reinforcement learning algorithm based traffic control approach can be applied to get optimal scheduling policy. The proposed Sarsa(λ)-based real-time traffic control optimization model can maintain the traffic signal timing policy more effectively. The Sarsa(λ)-based model gains traffic cost of the vehicle, which considers delay time, the number of waiting vehicles, and the integrated saturation from its experiences to learn and determine the optimal actions. The experiment results show an inspiring improvement in traffic control, indicating the proposed model is capable of facilitating real-time dynamic traffic control.

A Sarsa(λ)-Based Control Model for Real-Time Traffic Light Coordination

PubMed Central

Zhu, Fei; Liu, Quan; Fu, Yuchen; Huang, Wei

2014-01-01

Traffic problems often occur due to the traffic demands by the outnumbered vehicles on road. Maximizing traffic flow and minimizing the average waiting time are the goals of intelligent traffic control. Each junction wants to get larger traffic flow. During the course, junctions form a policy of coordination as well as constraints for adjacent junctions to maximize their own interests. A good traffic signal timing policy is helpful to solve the problem. However, as there are so many factors that can affect the traffic control model, it is difficult to find the optimal solution. The disability of traffic light controllers to learn from past experiences caused them to be unable to adaptively fit dynamic changes of traffic flow. Considering dynamic characteristics of the actual traffic environment, reinforcement learning algorithm based traffic control approach can be applied to get optimal scheduling policy. The proposed Sarsa(λ)-based real-time traffic control optimization model can maintain the traffic signal timing policy more effectively. The Sarsa(λ)-based model gains traffic cost of the vehicle, which considers delay time, the number of waiting vehicles, and the integrated saturation from its experiences to learn and determine the optimal actions. The experiment results show an inspiring improvement in traffic control, indicating the proposed model is capable of facilitating real-time dynamic traffic control. PMID:24592183

Overview of Airport Surface Traffic Control - Present and Future

DOT National Transportation Integrated Search

1975-09-01

The Airport Surface Traffic Control System, an integral part of the nation's Air Traffic Control System, is specifically concerned with the safe and efficient control of airport airside surface traffic. The current status of airport surface traffic c...

14 CFR 170.13 - Airport Traffic Control Tower (ATCT) establishment criteria.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airport Traffic Control Tower (ATCT... AIR TRAFFIC CONTROL SERVICES AND NAVIGATIONAL FACILITIES Airport Traffic Control Towers § 170.13 Airport Traffic Control Tower (ATCT) establishment criteria. (a) The following criteria along with general...

EPRI/SCE testing and evaluation of electric work vehicles: Jet 500, Volkswagen Type 2, DAUG Type GM2, and Battronic Minivan

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCluskey, R.K.; Arias, J.L.

1979-12-01

During the first 11 months of the EPRI/SCE Electric Vehicle Project, four electric vehicles (EVs) were tested and evaluated: the Jet Industries Electra-Van Model 500, the Volkswagen (VW) Type 2 Electrotransporter, a VW Type GM2 Transporter with DAUG electric drive, and the Battronic Minivan. The project emphasized road-testing of these vehicles to acquire data on their useful driving range, performance, and reliability. Each vehicle was driven more than 1000 miles along SCE-selected test routes to determine the effects of different terrains (level, slight grades, and steep grades), traffic conditions (one, two, three, and four stops/mile and freeway), and payload. Themore » vehicle component failures that occurred during testing are itemized and described briefly, and assessments of expected field reliability are made. Other vehicle characteristics and measurements of interest are presented. The data base on these test vehicles is intended to provide the reader an overview of the real world performance that can be expected from present-day state-of-the-art EVs.« less

Evaluation and enhancement of Texas ramp metering strategies, compliance, and alternative enforcement techniques: Go with the flow Houston. Public outreach plan (revised); Interim research report, September 1995--October 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lancaster, S.; Fette, B.; Busler, L.

This report describes the public outreach plan on the implementation of ramp meters along the Katy Freeway in Houston, Generally, ramp metering is neither beloved nor understood by the public. To gain public awareness, acceptance, compliance and continued support, ramp metering operations should be reinforced by a strong, ongoing public information and outreach campaign that communicates the need for and benefits of the program. Because the term `ramp metering` exhibits restrictions on the public, the phrase `Flow Signals` was developed to better describe the benefits of ramp metering; enhanced flow of traffic, fewer bottlenecks, and fewer trip delays. The logo,more » `Go with the Flow Houston,` and a graphic identity were developed to help communicate the theme throughout the various media where both the primary and secondary messages are intended to reach 15 different audiences. These media will include: a PSA, both static and changeable message signs, a brochure, Internet web site information, letters to specific audience and media relations efforts.« less

Safety evaluation of joint and conventional lane merge configurations for freeway work zones.

PubMed

Ishak, Sherif; Qi, Yan; Rayaprolu, Pradeep

2012-01-01

Inefficient operation of traffic in work zone areas not only leads to an increase in travel time delays, queue length, and fuel consumption but also increases the number of forced merges and roadway accidents. This study evaluated the safety performance of work zones with a conventional lane merge (CLM) configuration in Louisiana. Analysis of variance (ANOVA) was used to compare the crash rates for accidents involving fatalities, injuries, and property damage only (PDO) in each of the following 4 areas: (1) advance warning area, (2) transition area, (3) work area, and (4) termination area. The analysis showed that the advance warning area had higher fatality, injury, and PDO crash rates when compared to the transition area, work area, and termination area. This finding confirmed the need to make improvements in the advance warning area where merging maneuvers take place. Therefore, a new lane merge configuration, called joint lane merge (JLM), was proposed and its safety performance was examined and compared to the conventional lane merge configuration using a microscopic simulation model (VISSIM), which was calibrated with real-world data from an existing work zone on I-55 and used to simulate a total of 25 different scenarios with different levels of demand and traffic composition. Safety performance was evaluated using 2 surrogate measures: uncomfortable decelerations and speed variance. Statistical analysis was conducted to determine whether the differences in safety performance between both configurations were significant. The safety analysis indicated that JLM outperformed CLM in most cases with low to moderate flow rates and that the percentage of trucks did not have a significant impact on the safety performance of either configuration. Though the safety analysis did not clearly indicate which lane merge configuration is safer for the overall work zone area, it was able to identify the possibly associated safety changes within the work zone area under different traffic conditions. Copyright © 2012 Taylor & Francis Group, LLC

Impacts of carpool utilization on the Katy Freeway Transitway 42-month after evaluation. Interim report, September 1984-September 1989

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hawkins, H.G.; Christiansen, D.L.

1989-09-01

A major commitment has been made in the Houston area to develop physically separated transitways in the medians of freeways. The lanes are reserved for high-occupancy vehicles. Phase 1 of the first completed transitway opened on the Katy Freeway (I-10) in October 1984. The research study, funded jointly by the Metropolitan Transit Authority of Harris County and the Texas State Department of Highways and Public Transportation, was initiated in order to conduct a comprehensive analysis of the effects of permitting carpools to utilize the transitway. The report documents data collected in October 1988, 3.5 years after carpool utilization of themore » transitway began. The report compares the 1988 data to similar data collected before carpool utilization was permitted (March 1985) and after carpool utilization was permitted (April 1986, October 1987). These comparisons address numerous concerns and provide an indication of the effectiveness of allowing carpools on the transitway.« less

Impacts of carpool utilization on the Katy Freeway transitway 30-month after evaluation. Interim report, September 1984-April 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christiansen, D.L.; McCasland, W.R.

1988-09-01

A major commitment has been made in the Houston area to develop physically separated transitways in the medians of freeways. The lanes are reserved for high-occupancy vehicles. Phase I of the first completed transitway opened on the Katy Freeway (I-10) in October 1984. Phase 2 opened in June 1987. To increase potential utilization of the facility, carpools began using the transitway on a test basis in April 1985. The research study, funded jointly by the Metropolitan Transit Authority of Harris County and the Texas State Department of Highways and Public Transportation, was initiated to undertake a comprehensive analysis of themore » effects of permitting carpool utilization. The report documents the data collected in October 1987, 2.5 years after carpool utilization of the transitway was permitted. In the report, these data are compared to similar data collected both before carpool utilization was permitted and on several occasions after carpool utilization was permitted.« less

New findings regarding the significance of pavement skid resistance for road safety on Swiss freeways.

PubMed

Lindenmann, H P

2006-01-01

The significance of the influence of poor pavement skid resistance values on accident frequency in wet pavement conditions has been the object of many studies over several years. The various investigations have produced very diverse findings. Only seldom, however, has detailed consideration been given to the central question of whether pavement skid resistance is a decisive parameter in the occurrence of local accident "black spots." Until now, the focus has been more on describing a relationship between pavement skid resistance and accident frequency. In the course of the network-wide survey of the states of pavements and of accident occurrence on Switzerland's freeways from 1999 to 2003, it emerged that a relationship with inadequate pavement skid resistance was provable for only a small proportion of accident black spots. These findings were used to frame a guideline for authorities and highway operators about how to treat skid resistance when assessing pavements and accident occurrence on freeways.

76 FR 54156 - National Standards for Traffic Control Devices; the Manual on Uniform Traffic Control Devices for...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-31

... traffic control device design, location, or operation that have made some existing devices in the field...-2010-0159] RIN 2125-AF43 National Standards for Traffic Control Devices; the Manual on Uniform Traffic Control Devices for Streets and Highways; Revision AGENCY: Federal Highway Administration (FHWA...

77 FR 28460 - National Standards for Traffic Control Devices; the Manual on Uniform Traffic Control Devices for...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-14

...-2010-0159] RIN 2125-AF43 National Standards for Traffic Control Devices; the Manual on Uniform Traffic Control Devices for Streets and Highways; Revision AGENCY: Federal Highway Administration (FHWA..., approved by the FHWA, and recognized as the national standard for traffic control devices used on all...

Asthma exacerbation and proximity of residence to major roads: a population-based matched case-control study among the pediatric Medicaid population in Detroit, Michigan

PubMed Central

2011-01-01

Background The relationship between asthma and traffic-related pollutants has received considerable attention. The use of individual-level exposure measures, such as residence location or proximity to emission sources, may avoid ecological biases. Method This study focused on the pediatric Medicaid population in Detroit, MI, a high-risk population for asthma-related events. A population-based matched case-control analysis was used to investigate associations between acute asthma outcomes and proximity of residence to major roads, including freeways. Asthma cases were identified as all children who made at least one asthma claim, including inpatient and emergency department visits, during the three-year study period, 2004-06. Individually matched controls were randomly selected from the rest of the Medicaid population on the basis of non-respiratory related illness. We used conditional logistic regression with distance as both categorical and continuous variables, and examined non-linear relationships with distance using polynomial splines. The conditional logistic regression models were then extended by considering multiple asthma states (based on the frequency of acute asthma outcomes) using polychotomous conditional logistic regression. Results Asthma events were associated with proximity to primary roads with an odds ratio of 0.97 (95% CI: 0.94, 0.99) for a 1 km increase in distance using conditional logistic regression, implying that asthma events are less likely as the distance between the residence and a primary road increases. Similar relationships and effect sizes were found using polychotomous conditional logistic regression. Another plausible exposure metric, a reduced form response surface model that represents atmospheric dispersion of pollutants from roads, was not associated under that exposure model. Conclusions There is moderately strong evidence of elevated risk of asthma close to major roads based on the results obtained in this population-based matched case-control study. PMID:21513554

Emissions from an international airport increase particle number concentrations 4-fold at 10 km downwind.

PubMed

Hudda, Neelakshi; Gould, Tim; Hartin, Kris; Larson, Timothy V; Fruin, Scott A

2014-06-17

We measured the spatial pattern of particle number (PN) concentrations downwind from the Los Angeles International Airport (LAX) with an instrumented vehicle that enabled us to cover larger areas than allowed by traditional stationary measurements. LAX emissions adversely impacted air quality much farther than reported in previous airport studies. We measured at least a 2-fold increase in PN concentrations over unimpacted baseline PN concentrations during most hours of the day in an area of about 60 km(2) that extended to 16 km (10 miles) downwind and a 4- to 5-fold increase to 8-10 km (5-6 miles) downwind. Locations of maximum PN concentrations were aligned to eastern, downwind jet trajectories during prevailing westerly winds and to 8 km downwind concentrations exceeded 75 000 particles/cm(3), more than the average freeway PN concentration in Los Angeles. During infrequent northerly winds, the impact area remained large but shifted to south of the airport. The freeway length that would cause an impact equivalent to that measured in this study (i.e., PN concentration increases weighted by the area impacted) was estimated to be 280-790 km. The total freeway length in Los Angeles is 1500 km. These results suggest that airport emissions are a major source of PN in Los Angeles that are of the same general magnitude as the entire urban freeway network. They also indicate that the air quality impact areas of major airports may have been seriously underestimated.

Evaluating the impacts of grades on vehicular speeds on interstate highways

PubMed Central

Li, Zhibin; Wang, Yinhai; Cui, Zhiyong; Shi, Chaojian; Wu, Huafeng

2017-01-01

Grade variation on interstate highways affects the roadway geometric design, vehicle performance and driver behavior, thus possibly exerting an unexpected effect on vehicular speed. Hence, determining the internal relationship between grade and speed is important and useful for drivers, traffic regulators and other traffic participants. However, the problem with performing this research is the lack of large-scale gradient and speed data. Google Earth (GE) provides an application programming interface for extracting elevation data worldwide. The elevation dataset from GE can be easily converted to grade data. In addition, our team has collected and stored speed series data for different freeways over several years. Based on the above obtainable grade and speed datasets, we conducted research on the effect of grades on free flow speeds from two perspectives. First, the influence of grades on speed was analyzed from both quantitative and qualitative aspects. The analysis of the distributions of four typical types of speeds demonstrated a decreasing tendency as the speed increased. Steeper grades generated a more intense speed fluctuation in terms of the four types of speeds. Second, a model based on the Student’s t-test was developed to evaluate the level of significant difference among speed series under neighboring grades. The Student’s t-test demonstrated that adjacent grades do not significantly influence the speeds. In summary, speeds under different grades showed obviously different tendencies. The findings of this study can help transport authorities set more reasonable speed limits and improve the geometric design of interstates with grade variation constraints. PMID:28863157

Predicting drowsy driving in real-time situations: Using an advanced driving simulator, accelerated failure time model, and virtual location-based services.

PubMed

Wang, Junhua; Sun, Shuaiyi; Fang, Shouen; Fu, Ting; Stipancic, Joshua

2017-02-01

This paper aims to both identify the factors affecting driver drowsiness and to develop a real-time drowsy driving probability model based on virtual Location-Based Services (LBS) data obtained using a driving simulator. A driving simulation experiment was designed and conducted using 32 participant drivers. Collected data included the continuous driving time before detection of drowsiness and virtual LBS data related to temperature, time of day, lane width, average travel speed, driving time in heavy traffic, and driving time on different roadway types. Demographic information, such as nap habit, age, gender, and driving experience was also collected through questionnaires distributed to the participants. An Accelerated Failure Time (AFT) model was developed to estimate the driving time before detection of drowsiness. The results of the AFT model showed driving time before drowsiness was longer during the day than at night, and was longer at lower temperatures. Additionally, drivers who identified as having a nap habit were more vulnerable to drowsiness. Generally, higher average travel speeds were correlated to a higher risk of drowsy driving, as were longer periods of low-speed driving in traffic jam conditions. Considering different road types, drivers felt drowsy more quickly on freeways compared to other facilities. The proposed model provides a better understanding of how driver drowsiness is influenced by different environmental and demographic factors. The model can be used to provide real-time data for the LBS-based drowsy driving warning system, improving past methods based only on a fixed driving. Copyright © 2016 Elsevier Ltd. All rights reserved.

Stress in air traffic controllers : comparison of two air route traffic control centers on different shift rotation patterns.

DOT National Transportation Integrated Search

1975-01-01

Stress in 23 air traffic controllers (ATCS) at Atlanta Air Route Traffic Control Center (ATL) on the straight 5-day shift rotation schedule was compared with stress in 23 ATCS's on the 2-2-1 shift rotation schedule at Fort Worth Air Route Traffic Con...

Control of Networked Traffic Flow Distribution - A Stochastic Distribution System Perspective

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Hong; Aziz, H M Abdul; Young, Stan

Networked traffic flow is a common scenario for urban transportation, where the distribution of vehicle queues either at controlled intersections or highway segments reflect the smoothness of the traffic flow in the network. At signalized intersections, the traffic queues are controlled by traffic signal control settings and effective traffic lights control would realize both smooth traffic flow and minimize fuel consumption. Funded by the Energy Efficient Mobility Systems (EEMS) program of the Vehicle Technologies Office of the US Department of Energy, we performed a preliminary investigation on the modelling and control framework in context of urban network of signalized intersections.more » In specific, we developed a recursive input-output traffic queueing models. The queue formation can be modeled as a stochastic process where the number of vehicles entering each intersection is a random number. Further, we proposed a preliminary B-Spline stochastic model for a one-way single-lane corridor traffic system based on theory of stochastic distribution control.. It has been shown that the developed stochastic model would provide the optimal probability density function (PDF) of the traffic queueing length as a dynamic function of the traffic signal setting parameters. Based upon such a stochastic distribution model, we have proposed a preliminary closed loop framework on stochastic distribution control for the traffic queueing system to make the traffic queueing length PDF follow a target PDF that potentially realizes the smooth traffic flow distribution in a concerned corridor.« less

Prediction based active ramp metering control strategy with mobility and safety assessment

NASA Astrophysics Data System (ADS)

Fang, Jie; Tu, Lili

2018-04-01

Ramp metering is one of the most direct and efficient motorway traffic flow management measures so as to improve traffic conditions. However, owing to short of traffic conditions prediction, in earlier studies, the impact on traffic flow dynamics of the applied RM control was not quantitatively evaluated. In this study, a RM control algorithm adopting Model Predictive Control (MPC) framework to predict and assess future traffic conditions, which taking both the current traffic conditions and the RM-controlled future traffic states into consideration, was presented. The designed RM control algorithm targets at optimizing the network mobility and safety performance. The designed algorithm is evaluated in a field-data-based simulation. Through comparing the presented algorithm controlled scenario with the uncontrolled scenario, it was proved that the proposed RM control algorithm can effectively relieve the congestion of traffic network with no significant compromises in safety aspect.

77 FR 28455 - National Standards for Traffic Control Devices; the Manual on Uniform Traffic Control Devices for...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-14

... Options for design and applications of traffic control devices, this Manual should not be considered a... application of traffic control devices, as well as in the location and design of roads and streets that the..., while this Manual provides Standards, Guidance, and Options for design and applications of traffic...

Initial Air Traffic Control Training at Tartu Aviation College

DOT National Transportation Integrated Search

1997-01-01

A well developed air traffic control training system is vitally important for guaranteeing flight safety and the efficient provision of air traffic control services. During the Soviet era, air traffic control services in Estonia were provided by Aero...

Delay-feedback control strategy for reducing CO2 emission of traffic flow system

NASA Astrophysics Data System (ADS)

Zhang, Li-Dong; Zhu, Wen-Xing

2015-06-01

To study the signal control strategy for reducing traffic emission theoretically, we first presented a kind of discrete traffic flow model with relative speed term based on traditional coupled map car-following model. In the model, the relative speed difference between two successive running cars is incorporated into following vehicle's acceleration running equation. Then we analyzed its stability condition with discrete control system stability theory. Third, we designed a delay-feedback controller to suppress traffic jam and decrease traffic emission based on modern controller theory. Last, numerical simulations are made to support our theoretical results, including the comparison of models' stability analysis, the influence of model type and signal control on CO2 emissions. The results show that the temporal behavior of our model is superior to other models, and the traffic signal controller has good effect on traffic jam suppression and traffic CO2 emission, which fully supports the theoretical conclusions.

Simulation of traffic control signal systems

NASA Technical Reports Server (NTRS)

Connolly, P. J.; Concannon, P. A.; Ricci, R. C.

1974-01-01

In recent years there has been considerable interest in the development and testing of control strategies for networks of urban traffic signal systems by simulation. Simulation is an inexpensive and timely method for evaluating the effect of these traffic control strategies since traffic phenomena are too complex to be defined by analytical models and since a controlled experiment may be hazardous, expensive, and slow in producing meaningful results. This paper describes the application of an urban traffic corridor program, to evaluate the effectiveness of different traffic control strategies for the Massachusetts Avenue TOPICS Project.

Real-time characterization of particle-bound polycyclic aromatic hydrocarbons in ambient aerosols and from motor-vehicle exhaust

NASA Astrophysics Data System (ADS)

Polidori, A.; Hu, S.; Biswas, S.; Delfino, R. J.; Sioutas, C.

2007-12-01

A photo-electric aerosol sensor, a diffusion charger, an Aethalometer, and a continuous particle counter were used along with other real-time instruments to characterize the particle-bound polycyclic aromatic hydrocarbon (p-PAH) content, and the physical/chemical characteristics of aerosols collected a) in Wilmington (CA) near the Los Angeles port and close to 2 major freeways, and b) at a dynamometer testing facility in downtown Los Angeles (CA), where 3 diesel trucks were tested. In Wilmington, the p-PAH, surface area, particle number, and "black" carbon concentrations were 4-8 times higher at 09:00-11:00 a.m. than between 17:00 and 18:00 p.m., suggesting that during rush hour traffic people living in that area are exposed to a higher number of diesel combustion particles enriched in p-PAH coatings. Dynamometer tests revealed that the p-PAH emissions from the "baseline" truck (no catalytic converted) were up to 200 times higher than those from the 2 vehicles equipped with advanced emission control technologies, and increased when the truck was accelerating. In Wilmington, integrated filter samples were collected and analyzed to determine the concentrations of the most abundant p-PAHs. A correlation between the total p-PAH concentration (μg/m3) and the measured photo-electric aerosol sensor signal (fA) was also established. Estimated ambient p-PAH concentrations (Average = 0.64 ng/m3; Standard deviation = 0.46 ng/m3) were in good agreement with those reported in previous studies conducted in Los Angeles during a similar time period. Finally, we calculated the approximate theoretical lifetime (70 years per 24-h/day) lung-cancer risk in the Wilmington area due to inhalation of multi-component p-PAHs and "black" carbon. Our results indicate that the lung-cancer risk is highest during rush hour traffic and lowest in the afternoon, and that the genotoxic risk of the considered p-PAHs does not seem to contribute to a significant part of the total lung-cancer risk attributable to "black" carbon.

Real-time characterization of particle-bound polycyclic aromatic hydrocarbons in ambient aerosols and from motor-vehicle exhaust

NASA Astrophysics Data System (ADS)

Polidori, A.; Hu, S.; Biswas, S.; Delfino, R. J.; Sioutas, C.

2008-03-01

A photo-electric aerosol sensor, a diffusion charger, an Aethalometer, and a continuous particle counter were used along with other real-time instruments to characterize the particle-bound polycyclic aromatic hydrocarbon (p-PAH) content, and the physical/chemical characteristics of aerosols collected a) in Wilmington (CA) near the Los Angeles port and close to 2 major freeways, and b) at a dynamometer testing facility in downtown Los Angeles (CA), where 3 diesel trucks were tested. In Wilmington, the p-PAH, surface area, particle number, and "black" carbon concentrations were 4-8 times higher at 09:00-11:00 a.m. than between 17:00 and 18:00 p.m., suggesting that during rush hour traffic people living in that area are exposed to a higher number of diesel combustion particles enriched in p-PAH coatings. Dynamometer tests revealed that the p-PAH emissions from the "baseline" truck (no catalytic converter) were up to 200 times higher than those from the 2 vehicles equipped with advanced emission control technologies, and increased when the truck was accelerating. In Wilmington, integrated filter samples were collected and analyzed to determine the concentrations of the most abundant p-PAHs. A correlation between the total p-PAH concentration (μg/m3) and the measured photo-electric aerosol sensor signal (fA) was also established. Estimated ambient p-PAH concentrations (Average=0.64 ng/m3; Standard deviation=0.46 ng/m3 were in good agreement with those reported in previous studies conducted in Los Angeles during a similar time period. Finally, we calculated the approximate theoretical lifetime (70 years per 24-h/day) lung-cancer risk in the Wilmington area due to inhalation of multi-component p-PAHs and "black" carbon. Our results indicate that the lung-cancer risk is highest during rush hour traffic and lowest in the afternoon, and that the genotoxic risk of the considered p-PAHs does not seem to contribute to a significant part of the total lung-cancer risk attributable to "black" carbon.

47 CFR 80.325 - Control of distress traffic.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Control of distress traffic. 80.325 Section 80... Safety Procedures § 80.325 Control of distress traffic. (a) Distress traffic consists of all messages relating to the immediate assistance required by the mobile station in distress. In distress traffic, the...

Fast packet switching algorithms for dynamic resource control over ATM networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsang, R.P.; Keattihananant, P.; Chang, T.

1996-12-01

Real-time continuous media traffic, such as digital video and audio, is expected to comprise a large percentage of the network load on future high speed packet switch networks such as ATM. A major feature which distinguishes high speed networks from traditional slower speed networks is the large amount of data the network must process very quickly. For efficient network usage, traffic control mechanisms are essential. Currently, most mechanisms for traffic control (such as flow control) have centered on the support of Available Bit Rate (ABR), i.e., non real-time, traffic. With regard to ATM, for ABR traffic, two major types ofmore » schemes which have been proposed are rate- control and credit-control schemes. Neither of these schemes are directly applicable to Real-time Variable Bit Rate (VBR) traffic such as continuous media traffic. Traffic control for continuous media traffic is an inherently difficult problem due to the time- sensitive nature of the traffic and its unpredictable burstiness. In this study, we present a scheme which controls traffic by dynamically allocating/de- allocating resources among competing VCs based upon their real-time requirements. This scheme incorporates a form of rate- control, real-time burst-level scheduling and link-link flow control. We show analytically potential performance improvements of our rate- control scheme and present a scheme for buffer dimensioning. We also present simulation results of our schemes and discuss the tradeoffs inherent in maintaining high network utilization and statistically guaranteeing many users` Quality of Service.« less

A generic approach for examining the effectiveness of traffic control devices in school zones.

PubMed

Zhao, Xiaohua; Li, Jiahui; Ding, Han; Zhang, Guohui; Rong, Jian

2015-09-01

The effectiveness and performance of traffic control devices in school zones have been impacted significantly by many factors, such as driver behavioral attributes, roadway geometric features, environmental characteristics, weather and visibility conditions, region-wide traffic regulations and policies, control modes, etc. When deploying traffic control devices in school zones, efforts are needed to clarify: (1) whether traffic control device installation is warranted; and (2) whether other device effectively complements this traffic control device and strengthens its effectiveness. In this study, a generic approach is developed to examine and evaluate the effectiveness of various traffic control devices deployed in school zones through driving simulator-based experiments. A Traffic Control Device Selection Model (TCDSM) is developed and two representative school zones are selected as the testbed in Beijing for driving simulation implementation to enhance its applicability. Statistical analyses are conducted to extract the knowledge from test data recorded by a driving simulator. Multiple measures of effectiveness (MOEs) are developed and adopted including average speed, relative speed difference, and standard deviation of acceleration for traffic control device performance quantification. The experimental tests and analysis results reveal that the appropriateness of the installation of certain traffic control devices can be statistically verified by TCDSM. The proposed approach provides a generic framework to assess traffic control device performance in school zones including experiment design, statistical formulation, data analysis, simulation model implementation, data interpretation, and recommendation development. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mitigating and Tracking Black Carbon Exposure at Schools in the Mountain View Corridor of Salt Lake City

NASA Astrophysics Data System (ADS)

Roberts, P. T.; Brown, S. G.; Vaughn, D.; DeWinter, J. L.

2015-12-01

Black carbon (BC) is a short lived climate forcer and is associated with human health effects. We measured BC inside and outside at four schools in Salt Lake City during two studies in 2011-2014. In addition, PM2.5 was measured indoor and outdoor at one school, and gaseous air toxics outdoor at one school. The schools are within 500 m of a planned major freeway, and two of them will adjoin the freeway. The objectives included determining the outdoor and indoor concentrations of BC, the likely sources of BC, and once the freeway is built, the change in ambient BC at the schools. We determined the current state of air quality outdoors at these schools, to provide baseline data for comparison when the major freeway is operational, and indoors as a baseline before installing improved filtration to reduce BC in classrooms. Using MATES IV cancer risk values, we found that diesel particulate matter, as indicated by ambient, outdoor BC measurements, was responsible for 84% of the cancer risk at the schools. The HVAC system was moderately effective at filtrating PM mass (73% reduction), but very poor at filtering BC (7%-34% reduction), indicating that air toxics risk is similar indoors and outdoors. Improved filtration devices could potentially mitigate this risk, and improved filtration systems have been recommended for the schools. Lastly, we used the difference in absorption at two Aethalometer channels to determine that the majority of BC (> 90%) during the spring through fall is from fossil fuel emissions.

Emissions from an International Airport Increase Particle Number Concentrations 4-fold at 10 km Downwind

PubMed Central

2014-01-01

We measured the spatial pattern of particle number (PN) concentrations downwind from the Los Angeles International Airport (LAX) with an instrumented vehicle that enabled us to cover larger areas than allowed by traditional stationary measurements. LAX emissions adversely impacted air quality much farther than reported in previous airport studies. We measured at least a 2-fold increase in PN concentrations over unimpacted baseline PN concentrations during most hours of the day in an area of about 60 km2 that extended to 16 km (10 miles) downwind and a 4- to 5-fold increase to 8–10 km (5–6 miles) downwind. Locations of maximum PN concentrations were aligned to eastern, downwind jet trajectories during prevailing westerly winds and to 8 km downwind concentrations exceeded 75 000 particles/cm3, more than the average freeway PN concentration in Los Angeles. During infrequent northerly winds, the impact area remained large but shifted to south of the airport. The freeway length that would cause an impact equivalent to that measured in this study (i.e., PN concentration increases weighted by the area impacted) was estimated to be 280–790 km. The total freeway length in Los Angeles is 1500 km. These results suggest that airport emissions are a major source of PN in Los Angeles that are of the same general magnitude as the entire urban freeway network. They also indicate that the air quality impact areas of major airports may have been seriously underestimated. PMID:24871496

FAA Air Traffic Control Operations Concepts. Volume 7. ATCT (Airport Traffic Control Towers) Tower Controllers

DTIC Science & Technology

1989-04-21

kift rIn FAA AIR TRAFFIC CONTROL OPERATIONS CONCEPTS V olum e V iI:.................... ATCT Tower Controllers AmELECTE JUL 2 11989 21 April 1989 A...01 022.3013209-87-B 11 a FAA AIR TRAFFIC CONTROL OPERATIONS CONCEPTS VOLUME VII: ATCT TOWER CONTROLLERS CDRL Bl 12, VOL. VII CONTRACT DTF-AO1-85-Y...INCORPORATED 7150 Campus Drive, Suite 100 Colorado Springs, CO 80920 (719) 590-5100 DOT/FAA/AP-87-0i (VOL#7) 21 April 1989 FAA AIR TRAFFIC CONTROL OPERATIONS

Evaluation of New Jersey Route 18 OPAC/MIST traffic-control system

DOT National Transportation Integrated Search

1997-01-01

Conventional traffic-control strategies have limitations in handling unanticipated traffic demands. An adaptive traffic-signal control is expected to mitigate this problem and improve overall system performance. Furthermore, with the increasing needs...

Sediment-induced amplification and the collapse of the Nimitz Freeway

USGS Publications Warehouse

Hough, S.E.; Friberg, P.A.; Busby, R.; Field, E.F.; Jacob, K.H.; Borcherdt, R.D.

1990-01-01

THE amplification of ground motion by low-seismic-velocity surface sediments is an important factor in determining the seismic hazard specific to a given site. The Ms = 7.1 Loma Prieta earthquake of 17 October 1989 was the largest event in the contiguous United States in 37 years, and yielded an unparalleled volume of seismic data from the main shock and aftershock sequence1. These data can be used to image the seismic source, to study detailed Earth structure, and to study the propagation of seismic waves both through bedrock at depth and through sediment layers near the surface. Near the edge of San Francisco Bay, site conditions vary considerably on scales of hundreds of metres. The collapsed section of the two-tiered Nimitz Freeway in Oakland was built on San Francisco Bay mud, whereas stiffer alluvial sediments underlie a southern section that was damaged but did not collapse. Here we analyse high-quality, digital aftershock recordings from several sites near the Nimitz Freeway, and conclude that soil conditions and resulting ground-motion amplification may have contributed significantly to the failure of the structure.

Fixed Point Learning Based Intelligent Traffic Control System

NASA Astrophysics Data System (ADS)

Zongyao, Wang; Cong, Sui; Cheng, Shao

2017-10-01

Fixed point learning has become an important tool to analyse large scale distributed system such as urban traffic network. This paper presents a fixed point learning based intelligence traffic network control system. The system applies convergence property of fixed point theorem to optimize the traffic flow density. The intelligence traffic control system achieves maximum road resources usage by averaging traffic flow density among the traffic network. The intelligence traffic network control system is built based on decentralized structure and intelligence cooperation. No central control is needed to manage the system. The proposed system is simple, effective and feasible for practical use. The performance of the system is tested via theoretical proof and simulations. The results demonstrate that the system can effectively solve the traffic congestion problem and increase the vehicles average speed. It also proves that the system is flexible, reliable and feasible for practical use.

A survey of lead contamination in soil along Interstate 880, Alameda County, California.

PubMed

Teichman, J; Coltrin, D; Prouty, K; Bir, W A

1993-09-01

This study was undertaken to determine the levels of lead in soils taken from yards of homes in close proximity to a major freeway. Soils were collected from the yards of homes in communities adjacent to the freeway and within a 1-mile radius. Samples were analyzed using U.S. Environmental Protection Agency (EPA) methods and atomic absorption instrumentation. Ten percent of the samples were split and sent to a second laboratory for quality control. The possibility of lead-based paint contributing to the contamination was eliminated by sampling more than 20 feet from the homes. The soils closest to the highway showed lead levels exceeding California's and EPA's criteria for hazardous waste. A stratified sample of the depth of contamination in soils was also undertaken. Previously identified "hot spots" (soils with lead levels exceeding 500 ppm in the top 0.75 inch) were core sampled. Results indicated 90% of the subsurface samples contained lead exceeding the surface contaminations. This may be attributed to decades of urban lead-laden dust deposition. As the use of leaded gasolines have diminished in the past decade, the uppermost layers of soil/dust contained lower amounts of lead.

Automated Air Traffic Control Operations with Weather and Time-Constraints: A First Look at (Simulated) Far-Term Control Room Operations

NASA Technical Reports Server (NTRS)

Prevot, Thomas; Homola, Jeffrey R.; Martin, Lynne H.; Mercer, Joey S.; Cabrall, Christopher C.

2011-01-01

In this paper we discuss results from a recent high fidelity simulation of air traffic control operations with automated separation assurance in the presence of weather and time-constraints. We report findings from a human-in-the-loop study conducted in the Airspace Operations Laboratory (AOL) at the NASA Ames Research Center. During four afternoons in early 2010, fifteen active and recently retired air traffic controllers and supervisors controlled high levels of traffic in a highly automated environment during three-hour long scenarios, For each scenario, twelve air traffic controllers operated eight sector positions in two air traffic control areas and were supervised by three front line managers, Controllers worked one-hour shifts, were relieved by other controllers, took a 3D-minute break, and worked another one-hour shift. On average, twice today's traffic density was simulated with more than 2200 aircraft per traffic scenario. The scenarios were designed to create peaks and valleys in traffic density, growing and decaying convective weather areas, and expose controllers to heavy and light metering conditions. This design enabled an initial look at a broad spectrum of workload, challenge, boredom, and fatigue in an otherwise uncharted territory of future operations. In this paper we report human/system integration aspects, safety and efficiency results as well as airspace throughput, workload, and operational acceptability. We conclude that, with further refinements. air traffic control operations with ground-based automated separation assurance can be an effective and acceptable means to routinely provide very high traffic throughput in the en route airspace.

Assessment of Air Traffic Controller Acceptability of Aircrew Route Change Requests

NASA Technical Reports Server (NTRS)

Idris, Husni; Enea, Gabriele; Burke, Kelly; Wing, David

2017-01-01

NASA developed the traffic aware strategic aircrew requests concept for a cockpit automation that identifies route improvements and advises the aircrew to request the change from the air traffic controller. In order to increase the chance of air traffic control approval, the automation ensures that the route is clear of known traffic, weather, and airspace restrictions. Hence the technology is anticipated to provide benefits in areas such as flight efficiency, flight schedule compliance, passenger comfort, and pilot and controller workload. In support of a field trial of a prototype of the technology, observations were conducted at the Atlanta and Jacksonville air traffic control centers to identify the main factors that affect the acceptability of aircrew requests by air traffic controllers. Observers shadowed air traffic controllers as the test flight pilot made pre-scripted requests to invoke acceptability issues and then they interviewed voluntarily fifty controllers with experience ranging from one to thirty-five years. The most common reason for rejecting requests is conflicting with traffic followed by violating air traffic procedures, increasing sector workload, and conflicting with major arrival and departure flows and flow restrictions. Quantitative parameters such as the distance that a route should maintain from sector boundaries and special use airspace were identified and recommended for inclusion in the automation.

5 CFR 842.207 - Air traffic controllers.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 5 Administrative Personnel 2 2014-01-01 2014-01-01 false Air traffic controllers. 842.207 Section... (CONTINUED) FEDERAL EMPLOYEES RETIREMENT SYSTEM-BASIC ANNUITY Eligibility § 842.207 Air traffic controllers... misconduct, is entitled to an annuity— (1) After completing 25 years of service as an air traffic controller...

5 CFR 842.207 - Air traffic controllers.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 5 Administrative Personnel 2 2013-01-01 2013-01-01 false Air traffic controllers. 842.207 Section... (CONTINUED) FEDERAL EMPLOYEES RETIREMENT SYSTEM-BASIC ANNUITY Eligibility § 842.207 Air traffic controllers... misconduct, is entitled to an annuity— (1) After completing 25 years of service as an air traffic controller...

5 CFR 842.207 - Air traffic controllers.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 5 Administrative Personnel 2 2011-01-01 2011-01-01 false Air traffic controllers. 842.207 Section... (CONTINUED) FEDERAL EMPLOYEES RETIREMENT SYSTEM-BASIC ANNUITY Eligibility § 842.207 Air traffic controllers... misconduct, is entitled to an annuity— (1) After completing 25 years of service as an air traffic controller...

5 CFR 842.207 - Air traffic controllers.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false Air traffic controllers. 842.207 Section... (CONTINUED) FEDERAL EMPLOYEES RETIREMENT SYSTEM-BASIC ANNUITY Eligibility § 842.207 Air traffic controllers... misconduct, is entitled to an annuity— (1) After completing 25 years of service as an air traffic controller...

76 FR 80910 - Revised Notice of Intent To Prepare an Environmental Impact Statement for Military Training...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-27

... Boardman Northeast MOA would have two parts, A and B, with the current Boardman Air Traffic Control.... Civilian or other nonparticipating air traffic flying with an air traffic control clearance and under... civilian or other nonparticipating air traffic flying under VFR, or under IFR without air traffic control...

Dynamic Density: An Air Traffic Management Metric

NASA Technical Reports Server (NTRS)

Laudeman, I. V.; Shelden, S. G.; Branstrom, R.; Brasil, C. L.

1998-01-01

The definition of a metric of air traffic controller workload based on air traffic characteristics is essential to the development of both air traffic management automation and air traffic procedures. Dynamic density is a proposed concept for a metric that includes both traffic density (a count of aircraft in a volume of airspace) and traffic complexity (a measure of the complexity of the air traffic in a volume of airspace). It was hypothesized that a metric that includes terms that capture air traffic complexity will be a better measure of air traffic controller workload than current measures based only on traffic density. A weighted linear dynamic density function was developed and validated operationally. The proposed dynamic density function includes a traffic density term and eight traffic complexity terms. A unit-weighted dynamic density function was able to account for an average of 22% of the variance in observed controller activity not accounted for by traffic density alone. A comparative analysis of unit weights, subjective weights, and regression weights for the terms in the dynamic density equation was conducted. The best predictor of controller activity was the dynamic density equation with regression-weighted complexity terms.

Air Traffic Controller Working Memory: Considerations in Air Traffic Control Tactical Operations

DTIC Science & Technology

1993-09-01

INFORMATION PROCESSING SYSTEM 3 2. AIR TRAFFIC CONTROLLER MEMORY 5 2.1 MEMORY CODES 6 21.1 Visual Codes 7 2.1.2 Phonetic Codes 7 2.1.3 Semantic Codes 8...raise an awareness of the memory re- quirements of ATC tactical operations by presenting information on working memory processes that are relevant to...working v memory permeates every aspect of the controller’s ability to process air traffic information and control live traffic. The

An intelligent traffic controller

DOT National Transportation Integrated Search

1995-11-01

Advances in computing sciences have not been applied to traffic control. This paper describes the development of an intelligent controller. A controller with advanced control logic can significantly improve traffic flows at intersections. In this vei...

Neural networks for continuous online learning and control.

PubMed

Choy, Min Chee; Srinivasan, Dipti; Cheu, Ruey Long

2006-11-01

This paper proposes a new hybrid neural network (NN) model that employs a multistage online learning process to solve the distributed control problem with an infinite horizon. Various techniques such as reinforcement learning and evolutionary algorithm are used to design the multistage online learning process. For this paper, the infinite horizon distributed control problem is implemented in the form of real-time distributed traffic signal control for intersections in a large-scale traffic network. The hybrid neural network model is used to design each of the local traffic signal controllers at the respective intersections. As the state of the traffic network changes due to random fluctuation of traffic volumes, the NN-based local controllers will need to adapt to the changing dynamics in order to provide effective traffic signal control and to prevent the traffic network from becoming overcongested. Such a problem is especially challenging if the local controllers are used for an infinite horizon problem where online learning has to take place continuously once the controllers are implemented into the traffic network. A comprehensive simulation model of a section of the Central Business District (CBD) of Singapore has been developed using PARAMICS microscopic simulation program. As the complexity of the simulation increases, results show that the hybrid NN model provides significant improvement in traffic conditions when evaluated against an existing traffic signal control algorithm as well as a new, continuously updated simultaneous perturbation stochastic approximation-based neural network (SPSA-NN). Using the hybrid NN model, the total mean delay of each vehicle has been reduced by 78% and the total mean stoppage time of each vehicle has been reduced by 84% compared to the existing traffic signal control algorithm. This shows the efficacy of the hybrid NN model in solving large-scale traffic signal control problem in a distributed manner. Also, it indicates the possibility of using the hybrid NN model for other applications that are similar in nature as the infinite horizon distributed control problem.

Design of a final approach spacing tool for TRACON air traffic control

NASA Technical Reports Server (NTRS)

Davis, Thomas J.; Erzberger, Heinz; Bergeron, Hugh

1989-01-01

This paper describes an automation tool that assists air traffic controllers in the Terminal Radar Approach Control (TRACON) Facilities in providing safe and efficient sequencing and spacing of arrival traffic. The automation tool, referred to as the Final Approach Spacing Tool (FAST), allows the controller to interactively choose various levels of automation and advisory information ranging from predicted time errors to speed and heading advisories for controlling time error. FAST also uses a timeline to display current scheduling and sequencing information for all aircraft in the TRACON airspace. FAST combines accurate predictive algorithms and state-of-the-art mouse and graphical interface technology to present advisory information to the controller. Furthermore, FAST exchanges various types of traffic information and communicates with automation tools being developed for the Air Route Traffic Control Center. Thus it is part of an integrated traffic management system for arrival traffic at major terminal areas.

Toward the development of a new selection battery for air traffic control specialists.

DOT National Transportation Integrated Search

1979-09-01

In an effort to update and refine the selection battery for air traffic controllers, five experimental tests measuring aptitudes and skills considered important in air traffic work were administered to newly selected Air Traffic Control Specialist (A...

Planning in air traffic control

DOT National Transportation Integrated Search

2001-12-01

An experiment was conducted to examine the planning activities of en route air traffic controllers. : Controllers were placed in the role of planners and verbalized a plan for controlling traffic to a tactician : (another controller) who implemented ...

Analysis of pilot response time to time-critical air traffic control calls

DOT National Transportation Integrated Search

1991-08-01

One of the most important time-critical air traffic control messages for a pilot is one : that required an immediate maneuver for traffic avoidance. This study examines the time : required for an air traffic controller to successfully transmit such a...

Next-generation smart traffic signals : RHODES with Intellidrive, the self-taught traffic control system.

DOT National Transportation Integrated Search

2009-01-01

Can a self-calibrating signal control system lead to wider adoption of adaptive traffic control systems? The focus of Next Generation of Smart Traffic Signals, an Exploratory Advanced Research (EAR) Program project, is a system that-with lit...

A computerized traffic control algorithm to determine optimal traffic signal settings. Ph.D. Thesis - Toledo Univ.

NASA Technical Reports Server (NTRS)

Seldner, K.

1977-01-01

An algorithm was developed to optimally control the traffic signals at each intersection using a discrete time traffic model applicable to heavy or peak traffic. Off line optimization procedures were applied to compute the cycle splits required to minimize the lengths of the vehicle queues and delay at each intersection. The method was applied to an extensive traffic network in Toledo, Ohio. Results obtained with the derived optimal settings are compared with the control settings presently in use.

Preliminary Investigation of Workload on Intrastate Bus Traffic Controllers

NASA Astrophysics Data System (ADS)

Yen Bin, Teo; Azlis-Sani, Jalil; Nur Annuar Mohd Yunos, Muhammad; Ismail, S. M. Sabri S. M.; Tajedi, Noor Aqilah Ahmad

2016-11-01

The daily routine of bus traffic controller which involves high mental processes would have a direct impact on the level of workload. To date, the level of workload on the bus traffic controllers in Malaysia is relatively unknown. Excessive workload on bus traffic controllers would affect the control and efficiency of the system. This paper served to study the workload on bus traffic controllers and justify the needs to conduct further detailed research on this field. The objectives of this research are to identify the level of workload on the intrastate bus traffic controllers. Based on the results, recommendations will be proposed for improvements and future studies. The level of workload for the bus traffic controllers is quantified using questionnaire adapted from NASA TLX. Interview sessions were conducted for validation of workload. Sixteen respondents were involved and it was found that the average level of workload based on NASA TLX was 6.91. It was found that workload is not affected by gender and marital status. This study also showed that the level of workload and working experience of bus traffic controllers has a strong positive linear relationship. This study would serve as a guidance and reference related to this field. Since this study is a preliminary investigation, further detailed studies could be conducted to obtain a better comprehension regarding the bus traffic controllers.

76 FR 27743 - Notice of Availability of a Draft Environmental Assessment for a Proposed Airport Traffic Control...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-12

... Environmental Assessment for a Proposed Airport Traffic Control Tower and Base Building, University of Illinois... Availability of a Draft Environmental Assessment for a Proposed Airport Traffic Control Tower and Base Building...) proposes to fund, construct, and operate a new Airport Traffic Control Tower (ATCT) and Base Building at...

30 CFR 57.9100 - Traffic control.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Dumping Traffic Safety § 57.9100 Traffic control. To provide for the safe movement of self-propelled... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Traffic control. 57.9100 Section 57.9100 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE...

30 CFR 57.9100 - Traffic control.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Dumping Traffic Safety § 57.9100 Traffic control. To provide for the safe movement of self-propelled... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Traffic control. 57.9100 Section 57.9100 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE...

30 CFR 56.9100 - Traffic control.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Dumping Traffic Safety § 56.9100 Traffic control. To provide for the safe movement of self-propelled... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Traffic control. 56.9100 Section 56.9100 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE...

30 CFR 56.9100 - Traffic control.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Traffic control. 56.9100 Section 56.9100 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Dumping Traffic Safety § 56.9100 Traffic control. To provide for the safe movement of self-propelled...

30 CFR 56.9100 - Traffic control.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Traffic control. 56.9100 Section 56.9100 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Dumping Traffic Safety § 56.9100 Traffic control. To provide for the safe movement of self-propelled...

30 CFR 56.9100 - Traffic control.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Traffic control. 56.9100 Section 56.9100 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Dumping Traffic Safety § 56.9100 Traffic control. To provide for the safe movement of self-propelled...

30 CFR 57.9100 - Traffic control.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Traffic control. 57.9100 Section 57.9100 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Dumping Traffic Safety § 57.9100 Traffic control. To provide for the safe movement of self-propelled...

30 CFR 57.9100 - Traffic control.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Traffic control. 57.9100 Section 57.9100 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE... Dumping Traffic Safety § 57.9100 Traffic control. To provide for the safe movement of self-propelled...

Overview of the Arizona Quiet Pavement Program

NASA Astrophysics Data System (ADS)

Donavan, Paul; Scofield, Larry

2005-09-01

The Arizona Quiet Pavement Pilot Program (QP3) was initially implemented to reduce highway related traffic noise by overlaying most of the Phoenix metropolitan area Portland cement concrete pavement with a one inch thick asphalt rubber friction coarse. With FHWA support, this program represents the first time that pavement surface type has been allowed as a noise mitigation strategy on federally funded projects. As a condition of using pavement type as a noise mitigation strategy, ADOT developed a ten-year, $3.8 million research program to evaluate the noise reduction performance over time. Historically, pavement surface type was not considered a permanent solution. As a result, the research program was designed to specifically address this issue. Noise performance is being evaluated through three means: (1) conventional roadside testing within the roadway corridor (e.g., far field measurements within the right-of-way) (2) the use of near field measurements, both close proximity (CPX) and sound intensity (SI); and (3) far field measurements obtained beyond the noise barriers within the surrounding neighborhoods. This paper provides an overview of the program development, presents the research conducted to support the decision to overlay the urban freeway, and the status of current research.

A Novel Sensor System for Measuring Wheel Loads of Vehicles on Highways

PubMed Central

Zhang, Wenbin; Suo, Chunguang; Wang, Qi

2008-01-01

With the development of the highway transportation and business trade, vehicle Weigh-In-Motion (WIM) technology has become a key technology for measuring traffic loads. In this paper a novel WIM system based on monitoring of pavement strain responses in rigid pavement was investigated. In this WIM system multiple low cost, light weight, small volume and high accuracy embedded concrete strain sensors were used as WIM sensors to measure rigid pavement strain responses. In order to verify the feasibility of the method, a system prototype based on multiple sensors was designed and deployed on a relatively busy freeway. Field calibration and tests were performed with known two-axle truck wheel loads and the measurement errors were calculated based on the static weights measured with a static weighbridge. This enables the weights of other vehicles to be calculated from the calibration constant. Calibration and test results for individual sensors or three-sensor fusions are both provided. Repeatability, sources of error, and weight accuracy are discussed. Successful results showed that the proposed method was feasible and proven to have a high accuracy. Furthermore, a sample mean approach using multiple fused individual sensors could provide better performance compared to individual sensors. PMID:27873952

How to reduce workload--augmented reality to ease the work of air traffic controllers.

PubMed

Hofmann, Thomas; König, Christina; Bruder, Ralph; Bergner, Jörg

2012-01-01

In the future the air traffic will rise--the workload of the controllers will do the same. In the BMWi research project, one of the tasks is, how to ensure safe air traffic, and a reasonable workload for the air traffic controllers. In this project it was the goal to find ways how to reduce the workload (and stress) for the controllers to allow safe air traffic, esp. at huge hub-airports by implementing augmented reality visualization and interaction.

Characteristics of trace metals in traffic-derived particles in Hsuehshan Tunnel, Taiwan: size distribution, fingerprinting metal ratio, and emission factor

NASA Astrophysics Data System (ADS)

Lin, Y.-C.; Tsai, C.-J.; Wu, Y.-C.; Zhang, R.; Chi, K.-H.; Huang, Y.-T.; Lin, S.-H.; Hsu, S.-C.

2014-05-01

Traffic emissions are a significant source of airborne particulate matter (PM) in ambient environments. These emissions contain high abundance of toxic metals and thus pose adverse effects on human health. Size-fractionated aerosol samples were collected from May to September 2013 by using micro-orifice uniform deposited impactor (MOUDI). Sample collection was conducted simultaneously at the inlet and outlet sites of Hsuehshan Tunnel in northern Taiwan, which is the second longest freeway tunnel (12.9 km) in Asia. Such endeavor aims to characterize the chemical constituents, size distributions, and fingerprinting ratios, as well as the emission factors of particulate metals emitted by vehicle fleets. A total of 36 metals in size-resolved aerosols were determined through inductively coupled plasma mass spectrometry. Three major groups, namely, tailpipe emissions (Zn, Pb, and V), wear debris (Cu, Cd, Fe, Ga, Mn, Mo, Sb, and Sn), and resuspended dust (Ca, Mg, K, and Rb), of airborne PM metals were categorized on the basis of the results of enrichment factor, correlation matrix, and principal component analysis. Size distributions of wear-originated metals resembled the pattern of crustal elements, which were predominated by super-micron particulates (PM1-10). By contrast, tailpipe exhaust elements such as Zn, Pb, and V were distributed mainly in submicron particles. By employing Cu as a tracer of wear abrasion, several inter-metal ratios, including Fe/Cu (14), Ba/Cu (1.05), Sb/Cu (0.16), Sn/Cu (0.10), and Ga/Cu (0.03), served as fingerprints for wear debris. Emission factor of PM10 mass was estimated to be 7.7 mg vkm-1. The metal emissions were mostly predominated in super-micron particles (PM1-10). Finally, factors that possibly affect particulate metal emissions inside Hsuehshan Tunnel are discussed.

Driver hand-held cellular phone use: a four-year analysis.

PubMed

Eby, David W; Vivoda, Jonathon M; St Louis, Renée M

2006-01-01

The use of hand-held cellular (mobile) phones while driving has stirred more debate, passion, and research than perhaps any other traffic safety issue in the past several years. There is ample research showing that the use of either hand-held or hands-free cellular phones can lead to unsafe driving patterns. Whether or not these performance deficits increase the risk of crash is difficult to establish, but recent studies are beginning to suggest that cellular phone use elevates crash risk. The purpose of this study was to assess changes in the rate of hand-held cellular phone use by motor-vehicle drivers on a statewide level in Michigan. This study presents the results of 13 statewide surveys of cellular phone use over a 4-year period. Hand-held cellular phone use data were collected through direct observation while vehicles were stopped at intersections and freeway exit ramps. Data were weighted to be representative of all drivers traveling during daylight hours in Michigan. The study found that driver hand-held cellular phone use has more than doubled between 2001 and 2005, from 2.7% to 5.8%. This change represents an average increase of 0.78 percentage points per year. The 5.8% use rate observed in 2005 means that at any given daylight hour, around 36,550 drivers were conversing on cellular phones while driving on Michigan roadways. The trend line fitted to these data predicts that by the year 2010, driver hand-held cellular phone use will be around 8.6%, or 55,000 drivers at any given daylight hour. These results make it clear that cellular phone use while driving will continue to be an important traffic safety issue, and highlight the importance of continued attempts to generate new ways of alleviating this potential hazard.

Pedestrian Friendly Traffic Signal Control.

DOT National Transportation Integrated Search

2016-01-01

This project continues research aimed at real-time detection and use of pedestrian : traffic flow information to enhance adaptive traffic signal control in urban areas : where pedestrian traffic is substantial and must be given appropriate attention ...

The Conception Approach to the Traffic Control in Czech Cities - Examples from Prague

NASA Astrophysics Data System (ADS)

Tichý, Tomáš; Krajčír, Dušan

Modern and economic development of contemporary towns is without question highly dependent upon traffic infrastructure progress. Automobile transport intensity is dramatically rising in large towns and other Czech and European cities. At the same time number of traffic congestions and accidents is increasing, standing times are becoming longer and ecological stress is also escalated. To solve this situation seems to be the most effective solution to design intelligent traffic light intersection control system, variable message signs, preference of public transportation, road line traffic control and next telematics subsystems. This control system and subsystems should improve permeability of traffic road network with a respect for all demands on recent trends of traffic development in towns and regions.

Exposure to urban stressor and effects on free testosterone in female workers.

PubMed

Tomei, Gianfranco; Ciarrocca, Manuela; Fiore, Pina; Rosati, Maria Valeria; Pimpinella, Benedetta; Anzani, Maria Francesca; Giubilati, Roberto; Cangemi, Chiara; Tomao, Enrico; Tomei, Francesco

2008-03-25

The aim of the study is to evaluate if occupational exposure to chemical, physical and psycho-social urban stressor could cause alterations in plasma free testosterone (T) levels and related diseases in female traffic police vs. control group. The research was carried out on initial sample of 468 female Municipal Police employees (209 traffic police and 259 controls). After excluding the principal confounding factors, traffic police were matched with controls by age, working life, menstrual cycle day, BMI, drinking habit, cigarette smoking habit, liquorice and soy intake in diet, habitual consumption of Italian coffee. There were 96 female traffic police and 96 controls included in the study. T mean levels were significantly higher in female traffic police compared to controls (p=0.000). The distribution of T values in traffic police and in controls was significant (p=0.000). No significant differences were found comparing the percentage in traffic police and controls concerning dystocial, premature and post-term birth. An increase in mental health disorders was found in traffic police compared to controls but the difference was not significant. The increase in T plasma levels observed in traffic police vs. controls can be due to a chronic working exposure to low doses of environmental chemical urban stressor. According to our previous researches T could be used as an early biological marker even before the onset of the related disorders.

Simulating and evaluating an adaptive and integrated traffic lights control system for smart city application

NASA Astrophysics Data System (ADS)

Djuana, E.; Rahardjo, K.; Gozali, F.; Tan, S.; Rambung, R.; Adrian, D.

2018-01-01

A city could be categorized as a smart city when the information technology has been developed to the point that the administration could sense, understand, and control every resource to serve its people and sustain the development of the city. One of the smart city aspects is transportation and traffic management. This paper presents a research project to design an adaptive traffic lights control system as a part of the smart system for optimizing road utilization and reducing congestion. Research problems presented include: (1) Congestion in one direction toward an intersection due to dynamic traffic condition from time to time during the day, while the timing cycles in traffic lights system are mostly static; (2) No timing synchronization among traffic lights in adjacent intersections that is causing unsteady flows; (3) Difficulties in traffic condition monitoring on the intersection and the lack of facility for remotely controlling traffic lights. In this research, a simulator has been built to model the adaptivity and integration among different traffic lights controllers in adjacent intersections, and a case study consisting of three sets of intersections along Jalan K. H. Hasyim Ashari has been simulated. It can be concluded that timing slots synchronization among traffic lights is crucial for maintaining a steady traffic flow.

Air Traffic ControL : FAA Order 7110.65K

DOT National Transportation Integrated Search

1997-07-17

This order prescribes air traffic control procedures and phraseology for use by : personnel providing air traffic control services. Controllers are required to : be familiar with the provisions of this order that pertain to their operational : respon...

Buffalo Air Traffic Control Tower Operations Analysis.

DOT National Transportation Integrated Search

1981-09-01

This report provides a description of the non-surveillance aspects of the FAA air traffic control facility operation at Greater Buffalo International Airport from the air traffic controller's point of view. It includes photographs of all controller c...

Lattice hydrodynamic model based traffic control: A transportation cyber-physical system approach

NASA Astrophysics Data System (ADS)

Liu, Hui; Sun, Dihua; Liu, Weining

2016-11-01

Lattice hydrodynamic model is a typical continuum traffic flow model, which describes the jamming transition of traffic flow properly. Previous studies in lattice hydrodynamic model have shown that the use of control method has the potential to improve traffic conditions. In this paper, a new control method is applied in lattice hydrodynamic model from a transportation cyber-physical system approach, in which only one lattice site needs to be controlled in this control scheme. The simulation verifies the feasibility and validity of this method, which can ensure the efficient and smooth operation of the traffic flow.

A knowledge-based system for controlling automobile traffic

NASA Technical Reports Server (NTRS)

Maravas, Alexander; Stengel, Robert F.

1994-01-01

Transportation network capacity variations arising from accidents, roadway maintenance activity, and special events as well as fluctuations in commuters' travel demands complicate traffic management. Artificial intelligence concepts and expert systems can be useful in framing policies for incident detection, congestion anticipation, and optimal traffic management. This paper examines the applicability of intelligent route guidance and control as decision aids for traffic management. Basic requirements for managing traffic are reviewed, concepts for studying traffic flow are introduced, and mathematical models for modeling traffic flow are examined. Measures for quantifying transportation network performance levels are chosen, and surveillance and control strategies are evaluated. It can be concluded that automated decision support holds great promise for aiding the efficient flow of automobile traffic over limited-access roadways, bridges, and tunnels.

Pedestrian friendly traffic signal control : final research report.

DOT National Transportation Integrated Search

2016-01-01

This project continues research aimed at real-time detection and use of pedestrian : traffic flow information to enhance adaptive traffic signal control in urban areas : where pedestrian traffic is substantial and must be given appropriate attention ...

Effects of mental workload on physiological and subjective responses during traffic density monitoring: A field study.

PubMed

Fallahi, Majid; Motamedzade, Majid; Heidarimoghadam, Rashid; Soltanian, Ali Reza; Miyake, Shinji

2016-01-01

This study evaluated operators' mental workload while monitoring traffic density in a city traffic control center. To determine the mental workload, physiological signals (ECG, EMG) were recorded and the NASA-Task Load Index (TLX) was administered for 16 operators. The results showed that the operators experienced a larger mental workload during high traffic density than during low traffic density. The traffic control center stressors caused changes in heart rate variability features and EMG amplitude, although the average workload score was significantly higher in HTD conditions than in LTD conditions. The findings indicated that increasing traffic congestion had a significant effect on HR, RMSSD, SDNN, LF/HF ratio, and EMG amplitude. The results suggested that when operators' workload increases, their mental fatigue and stress level increase and their mental health deteriorate. Therefore, it maybe necessary to implement an ergonomic program to manage mental health. Furthermore, by evaluating mental workload, the traffic control center director can organize the center's traffic congestion operators to sustain the appropriate mental workload and improve traffic control management. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

[Modeling the vehicle pollution in the urban streets before and during the Beijing Olympic Games traffic control period].

PubMed

Wang, Ting; Xie, Shao-dong

2010-03-01

In order to investigate the vehicle pollution situation in the streets in Beijing and the abatement during the Olympic Games, the OSPM model was applied to calculate the concentrations of PM10, CO, NO2 and O3 inside the urban streets of Beijing before and during the Olympic traffic controlling period in July, 2008. The modeled concentrations before the traffic control are 146 micog/m3, 3.83 mg/m3, 114.4 microg/m3 and 4.71 x 10(-1), while after the traffic control are 112 microg/m3, 3.16 mg/m3, 102.4 microg/m3 and 5.31 x 10(-9) , with the reduction rates of 23.4%, 20.5%, 10.5% and -12.5%, respectively. The research on these concentration changes and the daily variations of the pollutants reveals: the concentration of PM10 is most influenced by the traffic control; the concentration of CO presents the most similar daily variation with the traffic flow; the reduction of NO2 concentration is limited, indicating the influence of other factors other than the traffic emission; the concentration of O3 increases after the traffic control, which means the traffic management measures can not abate the O3 pollution in the street. Furthermore, the comparison between the calculation results in different types of street canyons reveals that the fleet composition and street geometry impact the concentration changes. In a word, the vehicle pollution inside the streets of Beijing before the traffic control is relatively serious, as the concentrations of PM10, CO and NO2, all approach or exceed the Grade II National Air Quality Standard; the traffic control measures take effect in reducing the primary pollutants, but the secondary pollutants may increase after the traffic control.

Adaptive traffic signal control system (ACS-Lite) for Wolf Road, Albany, New York.

DOT National Transportation Integrated Search

2014-10-01

Adaptive Control Software Lite (ACS : - : Lite) is a : traffic : signal timing optimization system that : dynamically adjusts : traffic : signal timing : s : to meet current traffic demands. : The purpose of this : research project : was : to : deplo...

Development of a distance-to-roadway proximity metric to compare near-road pollutant levels to a central site monitor

NASA Astrophysics Data System (ADS)

Barzyk, Timothy M.; George, Barbara Jane; Vette, Alan F.; Williams, Ronald W.; Croghan, Carry W.; Stevens, Carvin D.

The primary objective of the Detroit Exposure and Aerosol Research Study (DEARS) was to compare air pollutant concentrations measured at various neighborhoods, or exposure monitoring areas (EMAs), throughout a major metropolitan area to levels measured at a central site or community monitor. One of the EMAs was located near a busy freeway (annual average daily traffic (AADT) of ˜130,000) so that impacts of mobile sources could be examined. Air pollution concentrations from the roadway-proximate sites were compared to the central site monitor. The volatile organic compounds (VOCs) selected (benzene, toluene, ethylbenzene, m,p- and o-xylene, 1,3 butadiene, 1,3,5-trimethylbenzene and 4-ethyltoluene) are typically associated with mobile sources. Gradients were also evident that demonstrated the amplification of pollutant levels near the roadway compared to the community monitor. A novel distance-to-roadway proximity metric was developed to plot the measurements and model these gradients. Effective distance represents the actual distance an air parcel travels from the middle of a roadway to a site and varies as a function of wind direction, whereas perpendicular distance is a fixed distance oriented normal to the roadway. Perpendicular distance is often used as a proxy for exposures to traffic emissions in epidemiological studies. Elevated concentrations of all the compounds were found for both a summer and winter season. Effective distance was found to be a statistically significant ( p < 0.05) univariate predictor for concentrations of toluene, ethylbenzene, m,p-xylene and o-xylene for summer 2005. For each of these pollutants, effective distance yielded lower p-values than the corresponding perpendicular distance models, and model fit improved. Results demonstrate that this near-road EMA had elevated levels of traffic-related VOCs compared to the community monitor, and that effective distance was a more accurate predictor of the degree to which they were elevated as a function of distance. Effective distance produced a range of distance-to-roadway values for a single site based on wind direction, thus increasing the number and range of values that could be used to plot and predict relative differences in pollutant concentrations between two sites.

Congestion control strategy on complex network with privilege traffic

NASA Astrophysics Data System (ADS)

Li, Shi-Bao; He, Ya; Liu, Jian-Hang; Zhang, Zhi-Gang; Huang, Jun-Wei

The congestion control of traffic is one of the most important studies in complex networks. In the previous congestion algorithms, all the network traffic is assumed to have the same priority, and the privilege of traffic is ignored. In this paper, a privilege and common traffic congestion control routing strategy (PCR) based on the different priority of traffic is proposed, which can be devised to cope with the different traffic congestion situations. We introduce the concept of privilege traffic in traffic dynamics for the first time and construct a new traffic model which taking into account requirements with different priorities. Besides, a new factor Ui is introduced by the theoretical derivation to characterize the interaction between different traffic routing selection, furthermore, Ui is related to the network throughput. Since the joint optimization among different kinds of traffic is accomplished by PCR, the maximum value of Ui can be significantly reduced and the network performance can be improved observably. The simulation results indicate that the network throughput with PCR has a better performance than the other strategies. Moreover, the network capacity is improved by 25% at least. Additionally, the network throughput is also influenced by privilege traffic number and traffic priority.

Traffic control systems handbook.

DOT National Transportation Integrated Search

2005-10-01

The Traffic Control Systems Handbook updates the 1996 edition (FHWA-SA-96-032). It serves as a basic reference in planning, designing and implementing traffic control systems. : Specific chapters include introduction, summary of available and emergin...

Traffic control systems handbook

DOT National Transportation Integrated Search

2005-10-01

The 2005 edition of "Traffic Control Systems Handbook" updates the 1996 edition (FHWA-SA-96-032). It serves as a basic reference in planning, designing and implementing traffic control systems. Specific chapters include introduction, summary of avail...

Impact of Automation Support on the Conflict Resolution Task in a Human-in-the-Loop Air Traffic Control Simulation

NASA Technical Reports Server (NTRS)

Mercer, Joey; Gomez, Ashley; Gabets, Cynthia; Bienert, Nancy; Edwards, Tamsyn; Martin, Lynne; Gujral, Vimmy; Homola, Jeffrey

2016-01-01

To determine the capabilities and limitations of human operators and automation in separation assurance roles, the second of three Human-in-the-Loop (HITL) part-task studies investigated air traffic controllers ability to detect and resolve conflicts under varying task sets, traffic densities, and run lengths. Operations remained within a single sector, staffed by a single controller, and explored, among other things, the controllers responsibility for conflict resolution with or without their involvement in the conflict detection task. Furthermore, these conditions were examined across two different traffic densities; 1x (current-day traffic) and a 20 increase above current-day traffic levels (1.2x). Analyses herein offer an examination of the conflict resolution strategies employed by controllers. In particular, data in the form of elapsed time between conflict detection and conflict resolution are used to assess if, and how, the controllers involvement in the conflict detection task affected the way in which they resolved traffic conflicts.

Self-control of traffic lights and vehicle flows in urban road networks

NASA Astrophysics Data System (ADS)

Lämmer, Stefan; Helbing, Dirk

2008-04-01

Based on fluid-dynamic and many-particle (car-following) simulations of traffic flows in (urban) networks, we study the problem of coordinating incompatible traffic flows at intersections. Inspired by the observation of self-organized oscillations of pedestrian flows at bottlenecks, we propose a self-organization approach to traffic light control. The problem can be treated as a multi-agent problem with interactions between vehicles and traffic lights. Specifically, our approach assumes a priority-based control of traffic lights by the vehicle flows themselves, taking into account short-sighted anticipation of vehicle flows and platoons. The considered local interactions lead to emergent coordination patterns such as 'green waves' and achieve an efficient, decentralized traffic light control. While the proposed self-control adapts flexibly to local flow conditions and often leads to non-cyclical switching patterns with changing service sequences of different traffic flows, an almost periodic service may evolve under certain conditions and suggests the existence of a spontaneous synchronization of traffic lights despite the varying delays due to variable vehicle queues and travel times. The self-organized traffic light control is based on an optimization and a stabilization rule, each of which performs poorly at high utilizations of the road network, while their proper combination reaches a superior performance. The result is a considerable reduction not only in the average travel times, but also of their variation. Similar control approaches could be applied to the coordination of logistic and production processes.

CATS-based Air Traffic Controller Agents

NASA Technical Reports Server (NTRS)

Callantine, Todd J.

2002-01-01

This report describes intelligent agents that function as air traffic controllers. Each agent controls traffic in a single sector in real time; agents controlling traffic in adjoining sectors can coordinate to manage an arrival flow across a given meter fix. The purpose of this research is threefold. First, it seeks to study the design of agents for controlling complex systems. In particular, it investigates agent planning and reactive control functionality in a dynamic environment in which a variety perceptual and decision making skills play a central role. It examines how heuristic rules can be applied to model planning and decision making skills, rather than attempting to apply optimization methods. Thus, the research attempts to develop intelligent agents that provide an approximation of human air traffic controller behavior that, while not based on an explicit cognitive model, does produce task performance consistent with the way human air traffic controllers operate. Second, this research sought to extend previous research on using the Crew Activity Tracking System (CATS) as the basis for intelligent agents. The agents use a high-level model of air traffic controller activities to structure the control task. To execute an activity in the CATS model, according to the current task context, the agents reference a 'skill library' and 'control rules' that in turn execute the pattern recognition, planning, and decision-making required to perform the activity. Applying the skills enables the agents to modify their representation of the current control situation (i.e., the 'flick' or 'picture'). The updated representation supports the next activity in a cycle of action that, taken as a whole, simulates air traffic controller behavior. A third, practical motivation for this research is to use intelligent agents to support evaluation of new air traffic control (ATC) methods to support new Air Traffic Management (ATM) concepts. Current approaches that use large, human-in-the-loop simulations are unquestionably valuable for this purpose, but pose considerable logistical, fiscal, and experimental control problems. First, data analysis is extremely complicated, owing simply to the large number of participants and data sources in such simulations. In addition, experienced human air traffic controllers working adjacent sectors tend to flexibly adapt to the evolving control problem - potentially shifting to other strategies than those under investigation. In addition, their performance is tightly coupled to the control interface, which in the development phase may support some concepts and supporting strategies better than others. A simple shift in strategy by one controller can change the character of a particular traffic scenario dramatically, which makes experimental comparison of ATC performance under different traffic scenarios difficult. Training a given team of controllers on operations under a new ATM concept for a sufficient period of time could avert such difficulties, but instituting an adequate training program is expensive and logistically difficult.

Effects of iterative learning based signal control strategies on macroscopic fundamental diagrams of urban road networks

NASA Astrophysics Data System (ADS)

Yan, Fei; Tian, Fuli; Shi, Zhongke

2016-10-01

Urban traffic flows are inherently repeated on a daily or weekly basis. This repeatability can help improve the traffic conditions if it is used properly by the control system. In this paper, we propose a novel iterative learning control (ILC) strategy for traffic signals of urban road networks using the repeatability feature of traffic flow. To improve the control robustness, the ILC strategy is further integrated with an error feedback control law in a complementary manner. Theoretical analysis indicates that the ILC-based traffic signal control methods can guarantee the asymptotic learning convergence, despite the presence of modeling uncertainties and exogenous disturbances. Finally, the impacts of the ILC-based signal control strategies on the network macroscopic fundamental diagram (MFD) are examined. The results show that the proposed ILC-based control strategies can homogenously distribute the network accumulation by controlling the vehicle numbers in each link to the desired levels under different traffic demands, which can result in the network with high capacity and mobility.

Evaluation of traffic responsive control on the Reston Parkway arterial network.

DOT National Transportation Integrated Search

2009-01-01

Traffic responsive plan selection (TRPS) control is considered an effective operational mode in traffic signal systems. Its efficiency stems from the fact that it can capture variations in traffic patterns and switch timing plans based on existing tr...

Application of color to reduce complexity in air traffic control.

DOT National Transportation Integrated Search

2002-11-01

The United States Air Traffic Control (ATC) system is designed to provide for the safe and efficient flow of air : traffic from origin to destination. The Federal Aviation Administration predicts that traffic levels will continue : increasing over th...

Evaluation of the effects of school zone signs and markings on speed reduction: a driving simulator study.

PubMed

Zhao, Xiaohua; Li, Jiahui; Ma, Jianming; Rong, Jian

2016-01-01

Traffic control devices are one of the most significant factors affecting driving behavior. In China, there is a lack of installation guidelines or standards for traffic control devices in school zones. In addition, little research has been done to examine the effects of traffic control devices on driving behavior. Few guidelines have been established for implementing traffic control devices in school zones in China. This research conducted a driving simulator experiment to assess the effects of school zone signs and markings for two different types of schools. The efficiency of these traffic control devices was evaluated using four variables derived from the driving simulation, including average speed, relative speed difference, standard deviation of acceleration, and 85th percentile speed. Results showed that traffic control devices such as the Flashing Beacon and School Crossing Ahead Warning Assembly, the Reduce Speed and School Crossing Warning Assembly, and the School Crossing Ahead Pavement Markings were recommended for school zones adjacent to a major multilane roadway, which is characterized by a median strip, high traffic volume, high-speed traffic and the presence of pedestrian crossing signals. The School Crossing Ahead Pavement Markings were recommended for school zones on a minor two-lane roadway, which is characterized by low traffic volume, low speed, and no pedestrian crossing signals.