Glossary of Transportation Terms

Employing a Continuing, Cooperative and Comprehensive (3C) planning process is a requirement for all MPOs as specified in 23 CFR 450.300.

AADT

Accessibility is the extent to which facilities are barrier free and useable by persons with disabilities, including wheelchair users.

Average Daily Traffic is the average number of vehicles passing a specific point in a 24-hour period, often measured throughout a year, it is a standard measurement for vehicle traffic-load on a section of road and is used when making transportation planning decisions.

The Clean Air Act is a United States federal law designed to control air pollution on a national level. It requires the Environmental Protection Agency (EPA) to develop and enforce regulations to protect the general public from exposure to airborne contaminants that are known to be hazardous to human health.

Conformity is a process in which transportation plans and spending programs are reviewed to ensure that they are consistent with federal clean air requirements; transportation projects collectively must not worsen air quality.

An Environmental Impact Statement is a comprehensive study required by the National Environmental Policy Act (NEPA) before certain types of major transportation projects may proceed.

Executive Order 12898 mandates that federal agencies address equity and fairness or Environmental Justice toward low-income and minority populations.

Any allowable expense actually incurred in implementing a particular capital or operating or capital program.

Making sure that a given program or project can reasonably expect to receive funding within the time allotted for its implementation.

Within the U.S. Department of Transportation, the Federal Transit Administration is responsible for public transit issues, including federal laws and regulations related to metropolitan transportation planning.

Federal Transit Administration Capital and Operating funds for urban areas.

Federal Transit Administration Capital and Operating funds for private and non-profit transportation providers in urban and rural areas.

Intelligent Transportation System refers to advanced technology applications which aim to improve transportation services and traffic management and enable users to be better informed and make safer, more coordinated and ‘smarter’ use of transportation networks. Examples include vehicle navigation systems, computerized signalization systems, surveillance cameras used to locate and clear accidents, etc., as well as electronic signs that notify drivers of traffic conditions.

Level of Service is a measuring technique used to gauge the level of efficiency of an individual roadway or a highway network; generally expressed as A, B, C, D, E, or F, with A being the lightest level of congestion and F being the heaviest.

Measures of Effectiveness are parameters describing the quality of service provided to drivers, passengers and pedestrians. Speed, delay, passenger loadings and transit vehicle travel time could be examples. Qualitative rankings such as Level of Service and On-Time Performance would be based on these measures.

Federal transportation laws and regulations require the establishment of a Metropolitan Planning Organization in every urbanized area of the U.S. with a population over 50,000. MPOs are responsible for meeting the federal metropolitan planning regulations for transportation.

The National Highway Institute is part of the Office of Professional and Corporate Development (OPCD) within the Federal Highway Administration (FHWA). NHI helps improve the performance of the transportation industry through training. To achieve this mission, NHI provides leadership and resources to guide the development and delivery of transportation-related training in many formats including both classroom-based and distance-based learning.

Any geographic region of the United States that the U.S. EPA has designated as not attaining the federal air quality standards for one or more air pollutants, such as ozone and carbon monoxide, is designated as a nonattainment area.

Designated parking areas for automobile drivers who then board transit vehicles or rideshare from these locations.

Indicators of how well the transportation system is performing with regard to such things as average speed, reliability of travel and accident rates. Used as feedback in the decision making process.

Movement in a direction opposite the main flow of traffic, such as from the central city to a suburb during the morning peak period.

Ridesharing is a form of transportation, other than public transit, in which more than one person shares the use of the vehicle, such as a van or car, to make a trip. Also known as “carpooling” or “vanpooling.”

Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users is the 2005 amendment of the U.S. Code Transportation section and related federal funding bill.

Metropolitan areas prepare local State Implementation Plans and regional areas prepare local and regional SIPs showing steps they plan to take to meet federal air quality standards.

Required by federal law, the State Transportation Improvement Program is a four-year “programmatic document” that requires joint FHWA and FTA approval and that portrays the projected use of legally committed federal “obligated dollars” to transportation projects over the course of the four year documents. The STIP is produced at least every four years (sometimes two years), and it is amended often.

Required by state law, the Six-Year Improvement Program is a six-year “programmatic document” that requires CTB approval and that portrays the state’s allocation of federal funds to transportation projects including the allocation and projected use of federal “obligated dollars” to those projects over the course of the first four years of the six year SYIP. The SYIP is produces and approved annually.

Transportation Control Measures are specific measures that reduce emissions by reducing vehicle use or reducing traffic flow, like improved public transit, shared-ride services, bicycle/pedestrian facilities and flexible work schedules.

The Transit Development Plan is an intermediate-range transit plan (usually five years) that examines service, markets and funding to make specific recommendations for transit improvements.

Developed and approved by the TPB, the Transportation Improvement Program is a list of projects and programs that will be implemented over the next six years. In order to receive federal funding, transportation projects must be included in the CLRP and the TIP.

Transportation Management Areas are urbanized areas over 200,000 in population, and any other area that requests such designation.

The Transportation Research Board’s mission is to promote innovation and progress in transportation by stimulating and conducting research, facilitating the dissemination of information and encouraging the implementation of research results.

U.S. Environmental Protection Agency is the federal agency responsible for federal environmental laws and regulations. EPA plays a central role in implementing the federal Clean Air Act, which deeply affects the metropolitan transportation planning process.

Volume/Capacity ratio: A ratio >1 indicates the facility is carrying more traffic than it can handle and improvements may be needed.

Virginia Department of Rail and Public Transportation is an agency under the Virginia Secretary of Transportation (as is VDOT) providing technical and financial assistance to Virginia’s public transit.