Assessment of Quantitative Mobile Source Air Toxics in Environmental Documents
Research Idea Scope
Background: Federal guidance requires detailed emission modeling for mobile source air toxic emissions (MSATs) for transportation projects that meet certain traffic and other criteria. As the development of the requisite emission forecasts typically requires significant time and resources to prepare, primarily due to the need for detailed network-based travel demand modeling, a simple screening process is needed to provide state and other transportation agencies a ready and cost-effective means to meet federal requirements for quantitative assessments for large projects (those that meet federal criteria for quantitative analyses) and reserve limited staff and other resources for more detailed project-specific studies for only the largest projects or those with the greatest potential impact. The proposed screening process would involve not only the development of a new modeling capability for screening but also recommendations for associated guidance. Additional options for screening would be considered as resources permit.
FHWA currently provides an interface model, EMIT, to facilitate the development of MSATs emission forecasts for NEPA documentation using relatively detailed network modeling-based travel demand forecasts and emission factors generated using MOBILE6.2, the model currently specified for use in regulatory applications by the US Environmental Protection Agency. A screening version of the EMIT interface model is not available.
This project will require close coordination with the US DOT to enhance the existing EMIT interface model and associated guidance to provide an option to screen projects based on emissions, using default worst-case assumptions for traffic. The consultant may alternatively create a new standalone interface model for this purpose. The screening interface model (based on EMIT, or new) would have the following key features:
· Ability to import emission factors or rates from output files generated by the new US EPA model MOVE2010 (and its successors) while maintaining, for a transition period, the same capability for MOBILE6.2 emission factors,
· Emission-based screening,
· Ability to generate standard charts and tables for inclusion in NEPA documentation and other materials for public review.
Additionally, to the extent that resources permit, other options for screening MSATs would also be explored as part of this project. The options to be considered would include:
· The development of a template for a Programmatic Agreement, including a separate Technical Support Document, to establish local screening criteria for MSATs analyses, and
· A review of the feasibility of using diesel particulate as a proxy for MSATs.
Research Objectives: The purpose of this research is to develop a simple emission-based screening process and model to provide state and other transportation agencies a ready and cost-effective means to meet federal requirements for quantitative assessments for MSATs. The screening process should reduce or eliminate the need for detailed project-specific modeling inputs such as network-based traffic forecasts. The project may be conducted most cost-effectively by building upon the existing USDOT model (EMIT) although a new standalone screening model may alternatively be created. Additionally, as resources permit, other options for screening should be explored, including: 1) the development of a template for a programmatic agreement that state DOTs may apply to establish local screening criteria for MSATs analyses, and 2) the use of emission forecasts for diesel particulate as a proxy for potential MSAT impacts.
The new screening interface model would generate standards sets of worst-case emission forecasts, including build/no-build comparisons as well as long-term trend lines for each MSAT pollutant, based on worst-case emission forecasts for various typical highway and transit projects. For example, the default project types could include new/expanded highways, new/improved interchanges, transit service changes, and new/improved intermodal centers. The screening interface model would provide default worst-case emission factors and per lane traffic volumes, which if applied for a given project would significantly reduce the time and resources required to estimate project-level MSAT emissions. The screening interface model must still allow for the input of project-specific data for emission factors and traffic volumes as well as other key factors such as the before and after number of lanes, speeds, and truck and bus percentages for use by state DOTs at their discretion.
The screening interface model would generate standard summary charts and tables for NEPA documentation and public review. The qualitative text for the federal guidance may need to be updated as appropriate for this purpose.
Finalize Scope of Work: The Consultant will work with the Research Panel to update and finalize the project scope of work. The final scope of work should include an overall work plan including a detailed schedule.
Model Development: The Consultant will create the new screening interface model per the final scope of work, with beta testing at key milestones. All work will be closely coordinated with the US DOT as appropriate.
NEPA Documentation Template: The Consultant will develop draft text for inclusion in project documentation for each project type for review by the Research Panel. The text will be based on the existing US DOT guidance for MSATs, updated as appropriate to reference the new screening process. The text is intended for US DOT consideration in their next update of guidance for MSATs and should not be finalized without US DOT agreement.
Case Studies: Once the new screening interface model has been developed and the associated draft text for NEPA documentation finalized, the Consultant will apply the model for each of the project types identified in the final scope of work and prepare corresponding sample project reports to meet NEPA requirements. The sample or template documentation should include the new charts and tables generated by the model.
[Optional, to be conducted as resources permit] Template Programmatic Agreement & Technical Support Document: Apply the new screening interface model for various typical project types and recommend appropriate thresholds for average daily traffic (ADT) for detailed quantitative MSAT analyses. Incorporate the recommended levels into a template programmatic agreement for MSATs that state DOTs can execute locally with FHWA. Prepare a technical support document showing the modeling approach and results. Update the NEPA documentation template (Task 3) to suit. All modeling files are to be included with the deliverables.
[Optional, to be conducted as resources permit] Diesel Particulate Proxy for MSATs: Apply the new screening interface model to assess the potential utility of using forecasts for diesel particulate as a proxy for potential impacts from MSATs. Develop recommendations. Update the NEPA documentation template (Task 3) to suit. All modeling files are to be included with the deliverables.
Progress Reports: The Consultant will monitor progress on all tasks and provide regular progress reports to the Research Panel.
 Federal Highway Administration, “Interim Guidance Update on Mobile Source Air Toxic Analysis in NEPA Documents”, September 30, 2009
TERI Administrator Note (June 2007): Related Research
WisDOT: Analyzing Mobile Source Air Toxics in the NEPA Process: Emerging State Practices and Research (2006)
TERI Administrator Note (June 2007): Related Research
FHWA: Interim Guidance on Air Toxic Analysis in NEPA Documents (2006)
John Zamurs, Chair Air Quality, Climate Change and Energy Subcommittee