• Air Toxics
• CMAQ
• Conformity

• Laws and Regulations
• Policy and Guidance
• Research
  • General Practice
  • Air Quality Planning and SIPs
  • Emissions Analysis
  • Land Use
  • Multi-Jurisdictional (Complex) Areas
  • Project Level Conformity
  • Small Urban and Rural Areas
  • Tools & Methodologies
  • Transportation Control Measures
• Reference Material
• Models & Methodologies
• Training

Research

A variety of research has been conducted by FHWA, EPA, and others related to all aspects of transportation conformity. Final reports for some of this research are provided below.

FHWA research is funded through the Surface Transportation Environment and Planning Cooperative Research Program (STEP), which was established by SAFETEA-LU. STEP is the sole source of SAFETEA-LU funds available to conduct all FHWA research on planning and environmental issues

All Documents

• Advances in Project Level Analyses or (PDF , 918KB) (November 2010) - Prepared by E.H. Pechan & Associates for FHWA, this report provides research results and methods for preparing project-level emissions analyses that take advantage of the capabilities of the MOVES emissions model.
• Modifying Link-Level Emissions Modeling Procedures for Applications within the MOVES Framework (September 2010) - Prepared by Eastern Research Group, Inc. for FHWA, the primary goal of the study was to ease the transition to the MOVES model by providing both a road map for developing updated emissions inventories, as well as an analysis of the likely impacts of the transition on the emissions inventories themselves.
• 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.
• MOBILE6 Implementation Experience (June 2005) - FHWA, in conjunction with the Association of Metropolitan Planning Organizations (AMPO) Air Quality Subcommittee, worked with a group of MPOs to document their experience in applying MOBILE6 in the conformity process. Thus purpose of the study is to provide an understanding of what steps these organizations took to prepare for use of the new MOBILE model and to identify potential training and technical assistance needs. Specifically, this study documents how MPOs are implementing MOBILE6, what data are being collected locally, and how data are being collected and identifies implementation issues that arose during the transition to MOBILE6.
• Emissions Benefits of Land Use Planning Strategies (or PDF, 3.1 MB) (December 2004) - Prepared by the Louis Berger Group for FHWA, this report documents what land use planning strategies are being considered for reduction of on-road mobile source emissions and how these strategies are being incorporated into various planning activities. It also documents the magnitude of the emissions benefits that were estimated and any consideration of relative cost-benefit analysis of the strategies. The report also examined the methodologies being used to measure the impacts of changes in terms of on-road moblie source emissions attributable to land use strategies and the additional research needs related to emissions benefits of land use strategies.
• Regional Emissions Analysis in Small Urban and Rural Areas (or PDF, 405 KB) (October 2004) - Prepared by ICF Consulting for FHWA, this report documents and assesses methodologies that can be used for estimating regional emissions for conformity analyses in small urban or rural areas. The report provides transportation practitioners a menu of methodologies and techniques for small urban or rural areas to consider for regional emissions analysis. The report also includes an assessment of these methodologies/techniques and highlights strengths and weaknesses of each.
• Implications of the Implementation of the MOBILE6 Emissions Factor Model on Project-Level Impact Analyses Using the CAL3QHC Dispersion Model (or PDF, 1.9 MB) (August 2004) - Prepared by ICF Consulting for FHWA, this report discusses how revisions to the MOBILE model affect the estimation of localized CO concentrations, including problems and difficulties in the interaction of MOBILE6 with CAL3QHC, as well as recommendations for addressing these issues. In addition, this report discusses how the implementation of MOBILE6 impacts screening assessment procedures.
• Screening Procedures for Project-Level Hotspot Analysis April 2004(or PDF 242 KB) - FHWA Resource Center paper that provides a summary of project-level CO screening procedures developed and adopted by transportation agencies throughout the nation, highlights several innovative practices, and offers recommendations for developing refined screening protocols
• Transportation Conformity Domestic Scan Report: Use of Latest Planning Assumptions and Transition to MOBILE6 (October 2003) - The FHWA transportaion conformity domestic scan was initiated to identify good practices among a select number of nonattainment and maintenance areas for meeting the transportation conformity requirements of the Clean Air Act. This project was targeted at identifying and sharing good practices in meeting the latest planning assumptions of the transportation conformity process. The study also highlighted areas' efforts to address data issues associated with the transition to EPA's most recent vehicle emissions model, MOBILE6. The scan team visited six sites in the eastern and southeastern part of the country and met with key transportation and air quality officials at each location.
• 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.
• 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.
• 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
• 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.
• MOVES Research - EPA reports provided on its MOVES website
• 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
• Sensitivity Analysis of MOBILE6 Motor Vehicle Emission Factor Model (or PDF) - FHWA Resource Center paper that provides a basic evaluation of the MOBILE6 model behavior under various conditions
• An Efficient Method To Assess Carbon Monoxide Pollutant For Transportation Projects - FHWA Resource Center paper about Florida DOT's use of a screening tool to assess worst-case CO scenarios
• Off-Model Air Quality Analysis: A Compendium of Practice - FHWA Resource Center paper about Off-Model methods (analyses performed without the specific use of a Travel Demand Model) being successfuly used in the South
• Transportation Conformity Practices in Complex Areas - FHWA conducted an assessment of how conformity determinations and regional emissions analyses are being done in the different types of complex nonattainment and maintenance areas