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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.

All Documents

• Evaluation of Methods for Modeling Vehicle Activity at Signalized Intersections for Air Quality Hot-Spot Analyses (October 2020) – Prepared by the Cadmus Group LLC for FHWA, this report summarizes an evaluation undertaken to compare methods of representing vehicle activity at signalized intersections for use in project scale air quality analysis. This evaluation is intended to advance the state of the practice for emissions and dispersion analysis at signalized intersections, which will improve the accuracy of pollutant concentration estimates.
• 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.
• Improving Vehicle Fleet, Activity, and Emissions Data for On-Road Mobile Sources Emissions Inventories (September 2011). Prepared by the University of California at Riverside for FHWA, this report investigates several modeling concepts and methodologies in the MOVES emissions model and explores new data sources and new methods for utilizing existing data sources to improve the emission inventory and analysis of on-road mobile sources.
• 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.
• 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 mobile 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.
• Transportation Conformity Domestic Scan Report: Use of Latest Planning Assumptions and Transition to MOBILE6 (October 2003) - The FHWA transportation
  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 - 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 (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
• 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