Transportation Conformity

Transportation conformity is a process that links a state's air quality efforts with its transportation planning activities. It requires multiple agencies and groups to work together to ensure that federal transportation dollars go to projects that are consistent with a state's air quality goals. The federal government requires transportation conformity in all geographic areas that fail to meet one or more National Ambient Air Quality Standards.

As part of transportation conformity, emissions analyses must be conducted for every proposed transportation plan, program or project in a nonattainment area. An emission analysis estimates the mobile source emissions that will likely result if a project is carried out. Analyses use the latest planning assumptions, traffic modeling, and federally approved emissions models.

The process is meant to ensure that new projects will not produce new air quality violations, worsen existing violations, or delay the timely attainment of air quality standards. For a project to receive federal funds, it must be shown that emissions resulting from it will not exceed the area's emissions budget. The budget is part of the state’s air quality plan, also known as the state implementation plan (SIP). The federal government cannot fund or approve transportation plans, programs or projects that do not conform to the SIP.

As the state's air quality planning agency, DHEC developed and is responsible for updating South Carolina's Transportation Conformity SIP in consultation with transportation agencies and air quality partners.

What is Tranportation Conformity? Health Effects of Pollutants Background Information

Transportation Conformity Memorandum of Agreement Lessons Learned from a Local Area Additional Resources

For additional information, contact:

Melinda Mathias - (803) 898-3269
SCDHEC Bureau of Air Quality
Planning
Fax: (803) 898-4487