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Transportation Control Measures

Under the Transportation Conformity Rule, Transportation Control Measures (TCMs) are strategies that:

  1. are specifically identified and committed to in State Implementation Plans (SIPs); and
  2. are either listed in Section 108 of the Clean Air Act (CAA) or will reduce transportation-related emissions by reducing vehicle use or improving traffic flow.

Measures that reduce emissions by improving vehicle technologies, fuels, or maintenance practices are not TCMs. Section 108 of the CAA provides examples of transportation control measures including, but not limited to:

Timely implementation of TCMs criterion must be satisfied before conformity determinations can be made. Consequently, TCMs receive the highest priority for funding under the Congestion Mitigation and Air Quality Improvement (CMAQ) Program.

Many other measures, similar to the TCMs listed in the CAA, are being used throughout the country to manage traffic congestion on streets and highways and to reduce vehicle emissions. Increasingly they are being recognized for their benefits toward improving an area's livability. These TCM type activities may be eligible for CMAQ funding, whether or not they are in approved SIPs, if they are documented to have emission reduction benefits in nonattainment and maintenance areas. These activities have been employed throughout the country for many years and include many travel demand management and transportation system management applications.

This website was designed to promote a better understanding of TCMs and the role they play in keeping America moving while reducing emissions. Information regarding TCM Effectiveness and TCM Methods and Models are provided. Additionally, TCM memoranda and links to other sites and documents are provided. These pages were prepared in partial fulfillment of Section 5107 of the Transportation Equity Act for the 21st Century that called for more information on transportation control measures.


Updated: 6/28/2017
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