Publication Detail

A Transportation Control Measure Taxonomy and Review of Recent TCM Effectiveness Studies


Research Report

Suggested Citation:
Guensler, Randall L. and Daniel Sperling (1992) A Transportation Control Measure Taxonomy and Review of Recent TCM Effectiveness Studies. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-92-17

In modern American society, technical fixes to existing transportation and environmental problems are almost exclusively relied upon, and are generally easier and more popular to implement than measures designed to achieve behavioral change. For instance, one survey found that motorists were much more willing to switch to alternative fuels than to use transit or carpool. Transportation control measures are strategies designed to improve the transportation system, and include both technical fixes as well as less popular behavioral change strategies.

"Transportation control measures are strategies designed to reduce vehicle trips, vehicle use, vehicle miles traveled, vehicle idling or traffic congestion for the purposes of reducing vehicle emissions (California Health and Safety Code (HSC) Section 40717 (g))."

Successful transportation control measures reduce air pollution, as well as energy consumption. However, in the U.S., the legal premise for the implementation of transportation control measures (TCMs) arises from legislation designed reduce air pollutant emissions. TCM implementation is required in areas violating air quality standards by the U.S. Clean Air Act (Public Law 101-549), as ammended in 1990, and by the California Clean Air Act of 1988. In addition, both the 1990 Clean Air Act Amendments (Section 176(c)) and the 1991 Intermodal Surface Transortation Efficiency Act (ISTEA) require transportation projects receiving federal funding to conform with air quality managment plan requirements.

This paper describes a taxonomy, or classification system, for transportation control measures. TCMs include transportation demand management (TDM) strategies, designed to change the tripmaking behavior of the individual. In addition, TCMs include supply improvement (TSI) strategies, designed to improve the existing transportation infrastructure, reduce congestion, and improve traffic flow. Historically, incremental TSI strategies have been included in highly structured air quality regulatory programs in the U.S., in combination with certain demand management strategies, under the label of transportation systems management.

Transportation demand management strategies have been divided into four classes: education and exhortation, regulatory mandates, economic incentives, and land use control. Transportation supply improvement strategies have been divided into three classes: traffic flow controls, construction and bottleneck relief, and intelligent vehicle and highway systems. Recognizing that no TCM taxonomy can establish completely discrete groupings of TCM strategies, the paper also discusses a number of stratgies that couple transportation demand management and supply improvement approaches into hybrid TCMs.