The National Academies

NCHRP 25-25/Task 89 [Completed]

Establishing Representative Background Concentrations for Quantitative Hot-spot Analyses for Particulate Matter
[ NCHRP 25-25 (Research for the AASHTO Committee on Environment and Sustainability) ]

  Project Data
Funds: $125,000
Research Agency: The Louis Berger Group, Inc.
Principal Investigator: Douglas Eisinger
Effective Date: 8/7/2013
Completion Date: 8/29/2014
Comments: Final deliverables available for AASHTO use

This study was requested by the American Association of State Highway and Transportation Officials (AASHTO), and conducted as part of the National Cooperative Highway Research Program (NCHRP) Project 25-25. The final deliverables are NOT official publications of the National Cooperative Highway Research Program, Transportation Research Board, National Research Council, or the National Academies.


Under EPA guidance certain transportation projects must be quantitatively evaluated to assess near-road particulate matter (PM) impacts. The PM hot-spot assessment involves estimating the incremental PM concentration originating from a proposed project, adding that increment to a representative background concentration, and determining whether the combination (increment plus background) meets conformity tests.  The purpose of this project was to develop step-by-step methods to help transportation project analysts estimate representative background concentrations for use in PM hot-spot conformity analyses.   In addition, the project addresses the influence of exceptional-type events on background concentration calculations.  The final deliverables for the project are as follows:

·         The agency’s final research report:  http://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP25-25(89)_FR.pdf  (Note: Revised October 2014 to include all case studies in Appendix C)

·         Appendices D and E in MS Word format to facilitate modifications by users:  http://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP25-25(89)_Documentation_Templates.docx

o   Background Concentration Documentation Template

o   Template for Addressing Data for Exceptional-Type and Air Transport Events in Background PM Calculations for PM Hot-Spot Analysis

·         Summary PowerPoint presentation:  http://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP25-25(89)_BackgroundPMConc.ppt





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