Air Quality Planning and SIPs
Transportation conformity ensures that Federal funding and approval goes to those transportation activities that are consistent with air quality goals and can have a significant impact on the transportation planning process. Transportation officials must be involved in the air quality planning process to ensure that emissions inventories, emissions budgets, and transportation control measures (TCMs) are appropriate and consistent with the transportation vision of a region.
Each State air quality agency is tasked with determining how best to achieve the Clean Air Act's (CAA's) goals and with developing state implementation plans (SIPs) for achieving health-based air quality standards. In some states, local air quality agencies also play a major role in air quality planning. SIPs are collections of regulations and measures used by a State to reduce emissions from stationary, area, and mobile sources and demonstrate attainment and maintenance of air quality standards. Decisions made in the air quality planning process and during SIP development can have a direct effect on transportation plans and projectcs. Transportation agencies need to participate fully in the air quality planning process to ensure that the decisions made reflect community priorities, including mobility.
- MOVES2010a Regional Level Sensitivity Analysis (December 2012) – Prepared by Volpe National Transportation Systems Center for FHWA, this document discusses the sensitivity of various input parameter effects on emission rates using MOVES2010a at the regional level. Pollutants included in the study are CO, NOx, PM2.5, and VOCs.
- Multi-Pollutant Emissions Benefits of Transportation Strategies (or PDF, 1.3 MB) (November 2006) - Prepared by ICF Consulting for FHWA, this report provides a compendium of traditional and innovative transportation-related control strategies. It identifies the emissions effects of the strategies on CO, PM10, PM2.5, NOx, VOCs, SOx, and NH3.
- Environmental Protection: Federal Planning Requirements for Transportation and Air Quality Protection Could Potentially Be More Efficient and Better Linked (April 2003) - This report documents the GAO's review of areas that have failed to demonstrate conformity and related conformity issues. The GAO reviewed all available data from EPA and DOT and conducted a Web-based survey of all MPOs and state air quality agencies. The GAO makes two recommendations that the relevant Federal agencies consider extending the 3-year time frame between required transportation plan updates and asking Congress to amend the Clean Air Act to change the conformity requirements to match, and to assess the advantages and disadvantages of statutorily requiring that the emissions budgets in air quality plans be regularly updated with new travel data and emissions models.
- Exhausting Options: Assessing SIP-Conformity Interactions (April 2003) - Prepared by Resources for the Future, Harvard University, and Sarah Siwek & Associates, this report evaluates SIP and transportation conformity interactions based on six case studies: Baltimore, MD; Houston, TX; Paducah, KY; Portland, OR; Sacramento, CA; and Washington, DC
- Transportation/Air Quality Issues in Rural Areas (April 2003) - Prepared by the Dye Management Group for FHWA, the purpose of this study was to increase understanding of how many rural areas are facing air quality issues and to identify the main causes for their exceeding air quality standards. The study focuses on transportation's contribution to the air quality problems in rural areas and how these areas are meeting certain Clean Air Act requirements related to motor vehicle emission sources.
- Linking Transportation and Air Quality Planning: Implementation of the Transportation Conformity Regulations in 15 Nonattainment Areas (March 1999) - Prepared by the Taubman Center for State and Local Government (Harvard University) for EPA and FHWA, this report documents the Conformity Assessment Project, which studied the implementation of the transportation conformity regulation in 15 nonattainment areas.
- An Overview of Federal Air Quality Legislation (or PDF, 1.24MB) - FHWA Resource Center paper that gives an overview of the U.S. Federal legislation in air quality as related to Federally assisted highway and transit program development.