The CLRP must conform to air quality improvement goals, and like financial constraint, air quality conformity is a federal requirement. Each year that the Constrained Long Range Plan (CLRP) and Transportation Improvement Program (TIP) are updated, TPB staff tests the draft CLRP and TIP to ensure that the projects in the plan, when considered collectively, meet general regulatory requirements, as well as specific requirements for each air quality plan (called a State Implementation Plan, or SIP) promulgated under the Clean Air Act Amendments of 1990. The analysis is documented in a report that describes the technical elements of the analysis such as travel demand forecasting, emissions calculation procedures, and impacts of transportation emission reduction measures. The analysis demonstrates that mobile source emissions, estimated for the TIP and for each analysis year of the long range plan, adhere to all carbon monoxide (CO) and ozone season volatile organic compound (VOC) and nitrogen oxides (NOx) budgets established by the Metropolitan Washington Air Quality Committee (MWAQC) and approved by the EPA. Tests are also done to ensure that PM2.5 pollutant (direct PM2.5 and precursor NOx) emissions are not greater than base year 2002 emissions.
Once the TPB finds that the CLRP meets regional air quality requirements, federal agencies certify that the plan is “in conformity.” In other words, the TPB ensures that the CLRP “conforms” to air quality improvement goals. If the TPB encounters difficulty in meeting conformity—or expects to—it may choose to adopt Transportation Emission Reduction Measures (TERMs), such as ridesharing and telecommuting programs, improved transit and bicycling facilities, clean fuel vehicle programs or other possible actions.
The Metropolitan Washington Air Quality Committee (MWAQC) is the entity certified, through delegation of responsibilities from the District of Columbia, Maryland and Virginia air management agencies, to prepare regional air quality plans for the Washington region. MWAQC includes local elected officials, representatives of the state and D.C. air management and transportation agencies, state legislators and the chair of the TPB. Like the TPB, MWAQC is housed at the Council of Governments (COG), which provides its staff. Transportation is integral to air quality planning. Regional air quality plans for CO, ozone, and PM2.5 each include one or more ceilings (“emissions budgets”) for emissions from mobile sources (cars, trucks and buses), as well as emissions reduction requirements for other sources of air pollution, such as power plants. The TPB must show that its transportation plans will conform to the mobile source emissions ceilings for specific milestone years established in the regional air quality plans.