Simplified Methodology for Risk-Based Air Quality Assessments of NEPA Alternatives

For state departments of transportation (DOTs), comparisons of alternative build and no-build scenarios in project-level air quality analyses can affect project selection and approval. These comparisons typically focus on emissions and/or ambient concentrations of specific pollutants, including greenhouse gases, mobile source air toxins, particulate matter, and carbon monoxide. However, the emission and concentration estimates between pollutant classes are not directly comparable and cannot be directly aggregated. As a result, decision-making on National Environmental Policy Act (NEPA) project alternative analyses becomes constrained, limiting the ability to consider potential multi-pollutant air quality impacts, which may differ substantially by alternative. One possible solution to this problem is to translate the results for each pollutant class into a common risk-based metric that would allow for aggregation and comparison. Potential synergistic effects could also be considered as part of the aggregation. NEPA alternatives could then be compared on the common basis of potential air quality impacts for each alternative in terms of aggregate risk. Research is needed to support the development of a simplified air quality risk assessment methodology that provides state DOTs with increased flexibility and capability to make informed air quality decisions at the project level. OBJECTIVE: The objective of this project is to develop (1) a guide for applying a simplified air quality risk assessment methodology for project-specific NEPA air quality alternative analyses to be used by state DOTs at their discretion and (2) a compendium of historical and notional case studies illustrating the developed risk assessment approach and its applications, which may be appended to NEPA air studies to add transparency and provide context to stakeholders.

• Record URL:
  • http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=5711
• Supplemental Notes:
  • Contract to a Performing Organization has not yet been awarded.

Language

• English

Project

• Funding: $450,000.00
• Contract Numbers:

  Project 25-75

• Sponsor Organizations:

  National Cooperative Highway Research Program

  Transportation Research Board
  500 Fifth Street, NW
  Washington, DC  United States  20001

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590

  American Association of State Highway and Transportation Officials (AASHTO)

  444 North Capitol Street, NW
  Washington, DC  United States  20001
• Project Managers:

  Brooks, Michael

• Start Date: 20250310
• Expected Completion Date: 0
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Air quality; Compliance; Decision making; Environmental justice; Environmental monitoring; Metrics (Quantitative assessment); Plan implementation; Risk assessment; State departments of transportation
• Subject Areas: Environment; Highways; Planning and Forecasting; Society;

Filing Info

• Accession Number: 01919358
• Record Type: Research project
• Source Agency: Transportation Research Board
• Contract Numbers: Project 25-75
• Files: TRB, RIP
• Created Date: May 22 2024 2:21PM