and VOCs and reduce NOx emissions from gasoline-fueled vehicles.

Transient emissions test—

An emissions test performed under a load that varies from moment to moment during the test.

Transportation control measure (TCM)—

Any control measure to reduce vehicle trips, vehicle use, vehicle miles traveled, vehicle idling, or traffic congestion for the purpose of reducing motor-vehicle emissions. TCMs can include encouraging the use of carpools and mass transit.

Transportation-demand management (TDM) strategies—

Strategies which use regulatory mandates, economic incentives, or education campaigns to change driver behavior. TDM strategies attempt to reduce the frequency or length of automobile trips or to shift the timing of automobile trips.

Transportation-supply improvement (TSI) strategies—

TSI strategies attempt to reduce emissions by changing the physical infrastructure of the road system to improve traffic flow and reduce stop-and-go movements.

Two-way catalytic converter—

A first generation catalytic converter designed to oxidize CO and VOC emissions from gasoline-fueled vehicles.

Urban airshed model (UAM)—

A three-dimensional photochemical air quality grid model for calculating the concentrations of both inert and chemically reactive pollutants in the atmosphere. It simulates the physical and chemical processes that affect concentrations of pollutants.

U.S. Environmental Protection Agency (EPA)—

The federal government agency that establishes regulations and oversees the enforcement of laws related to the environment.

Vehicle-miles traveled (VMT)—

The number of miles driven by a fleet of vehicles over a set period of time, such as a day, month, or year.

Sources: California Air Resources Board 2002; Davis 1997; EPA 2002; FHWA 2000; Harvey and Deakin 1993; IMRC 2000.

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