B:
Bridges - Science Tracer Bullet - Bridges - Science Tracer Bullets - Research Finding Aids from the Library of Congress, Science Reference Services. [U.S. Library of Congress (LOC)]

E:
Environmental Management - Responsible for the risk reduction and cleanup of the environmental legacy of the Nation's nuclear weapons program [U.S. Department of Energy (DOE), Office of Environmental Management (EM)]

N:
National Transportation Safety Board - The National Transportation Safety Board is an independent U.S. Federal agency that investigates every civil aviation accident in the United States and significant accidents in the other modes of transportation, conducts special investigations and safety studies, and issues safety recommendations to prevent future accidents. [Ad Hoc Organizations, National Transportation Safety Board]

R:
Record Group 198: Records of the Board of Investigation and Research-Transportation, 1940 - 1944 - National Archives' Archival Research Catalog description for Record Group 198: Records of the Board of Investigation and Research-Transportation, 1940 - 1944 [U.S. National Archives and Records Administration (NARA)]

T:
TSA: Advanced Imaging Technology - Technology to help ensure travel safety [U.S. Department of Homeland Security (DHS), Travel Security Administration]

TSA: Helpful Hints for Holiday Travelers - Helpful hints to be prepared for security before traveling [U.S. Department of Homeland Security (DHS), Transportation Security Administration]