Transportation Control Measures
Under the Transportation Conformity Rule, Transportation Control Measures (TCMs) are strategies that:
Under the Transportation Conformity Rule, Transportation Control Measures (TCMs) are strategies that:
- are specifically identified and committed to in State Implementation Plans (SIPs); and
- 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:
- improved public transit,
- traffic flow improvements and high-occupancy vehicle lanes,
- shared ride services,
- pedestrian/bicycle facilities, and
- flexible work schedules.
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.
In response to Section 5107 of the Transportation Equity Act for the 21st Century, which called for more information on transportation control measures, information regarding TCM Effectiveness and TCM Methods and Models were prepared.
Policy & Guidance
- Diesel Retrofits: Quantifying and Using Their Emission Benefits in SIPs and Conformity - Guidance for State and Local Air and Transportation Agencies (EPA, February 2014) - Guidance on quantifying and using emission reductions from on-road and nonroad diesel vehicles, engines, and equipment that have been retrofitted with emission reduction technology. This guidance supersedes EPA's June 2006 guidance under the same name.
- Commuter Programs: Quantifying and Using Their Emission Benefits in SIPs and Conformity (EPA, February 2014) - Guidance on how to estimate the emission benefits of commuter programs and, under appropriate circumstances, take credit for them in SIPs and conformity determinations. This guidance supersedes EPA's October 2007 document, "Guidance for Quantifying and Using Emission Reductions from Best Workplaces for Commuter Programs in State Implementation Plans and Transportation Conformity".
- Guidance for Implementing the Clean Air Act Section 176(c)(8) Transportation Control Measure Substitution and Addition Provision (January 2009) - EPA guidance on implementing the CAA provision that establishes a streamlined process for substituting or adding transportation control measures to an approved state air quality plan. Transportation control measures, such as public transit and carpooling, can provide alternatives to the public that reduce motor vehicle emissions. This document supersedes the section of the February 14, 2006, interim guidance on implementing the CAA amendments made by SAFETEA-LU that addressed this provision.
- Program Guidance on High Occupancy Vehicle Lanes (or PDF) (August 2008) - FHWA guidance on the planning, design, operation, and management of HOV facilities, as well as examples to follow in evaluating proposed significant changes to the operation of an HOV lane (e.g., conversion of an HOV lane to an HOT lane)
- SmartWay SIP and Transportation Conformity Guidance: Accounting for NOx Reductions from Trailer Aerodynamic Kits and Low Rolling Resistance Tires (June 2007) - EPA guidance that describes how to quantify and use reductions in nitrogen oxides (NOx) that result when trucks are outfitted with two specific SmartWay fuel-efficient technologies: trailer aerodynamic kits and low-rolling resistance tires
- Interim Guidance for Implementing the Transportation Conformity Provisions in SAFETEA-LU (February 2006) - Memorandum from FHWA, FTA, and EPA concerning guidance on implementing the transportation conformity-related provisions contained in SAFETEA-LU - this interim guidance pertained to the time period before the federal transportation conformity rule was revised.
- Guidance on Incorporating Bundled Measures in a State Implementation Plan (August 2005) - EPA guidance on SIP credit from a group ("bundle") of pollution control measures or strategies considered in the aggregate
- Guidance on Quantifying NOx Benefits for Cetane Improvement Programs for Use in SIPs and Transportation Conformity (June 2004) - EPA guidance quantifying emission reductions from the use of cetane improvement additives in diesel fuel. These emission reductions may be used either to meet SIP requirements or in transportation conformity determinations.
- Guidance on the Implementation of the March 2, 1999 Court Decision (January 2002) - Updated guidance from FHWA and FTA concerning approval for projects in nonattainment and maintenance areas that do not have a currently conforming transportation plan and transportation improvement program. Changes resulted from a case brought against EPA by the Environmental Defense Fund.
