Constituent groups: Constituent groups include private companies involved in various aspects of transportation, such as rail, truck, and marine carriers, airlines, and manufacturers and suppliers of equipment; state and local governments; the research community; and others such as transportation user groups and associations.

Intermodal: A transportation service making use of different modes of transportation.

Modal administrations: These are the organizational units within DOT that are responsible for the various transportation modes, namely, the Federal Aviation Administration (FAA), the Federal Highway Administration (FHWA), the Federal Railroad Administration (FRA), the Federal Transit Administration (FTA), the Maritime Administration (MARAD), the National Highway Traffic Safety Administration (NHTSA), and the U.S. Coast Guard (USCG). The Bureau of Transportation Statistics (BTS) is also included as one of the organizational units within DOT, although it is not responsible for any individual transportation mode.

Modes: These are the major types of transportation, namely, highway, water, rail, air, and pipeline.

Multimodal: Relating to or characterized by several different modes of transportation.

NSTC Transportation R&D Committee: This committee is a federal interagency planning group managed by the White House Office of Science and Technology Policy. The Deputy Secretary of Transportation, Mortimer Downey, and NASA's Associate Administrator for Aeronautics, Robert Whitehead, are Chair and Vice-Chair, respectively, of the NSTC Transportation R&D Committee.

R&D: See "S&T."

S&T: The terms "S&T" (science and technology) and "R&D" (research and development) are used interchangeably by the NSTC Committee on Transportation R&D to encompass basic research, applied research, technology development, technology deployment, engineering, and education and training. In DOD terminology, R&D includes all the aforementioned activities, whereas S&T encompasses only basic research, applied research, and technology development.

Transportation S&T Strategy Team: This interagency group, cochaired by NASA and the Policy Office of the Office of the Secretary of Transportation (OST), is working to develop a transportation S&T strategy under the auspices of the NSTC Transportation R&D Committee. Team members include representatives from the modal administrations within DOT, as well as from the U.S. Departments of Commerce, Defense, Energy, and State; the Environmental Protection Agency; and NASA. Representatives of OMB, OSTP, and the OST Budget Office also participate in team activities.