The National Academies

NCHRP 25-25/Task 96 [Final]

Quick Reference Guide for Traffic Modelers for Generating Traffic and Activity Data for Project-Level Air Quality Analyses
[ NCHRP 25-25 (Research for the AASHTO Committee on Environment and Sustainability) ]

  Project Data
Funds: $75,000
Research Agency: WSP
Principal Investigator: Ms. Helen Ginzburg
Effective Date: 11/4/2015
Completion Date: 5/31/2018

Status: Final report available HERE.  (Please note that the document includes several pages that are best printed on paper sized 11" x 17".)


There is a frequent disconnect between the traffic data needed for project-level air quality analysis and the traffic data provided by traffic modelers.  The disconnect leads to waste in processing and time and introduces project risk by introducing uncertainty into the NEPA and Transportation Conformity process. The challenge stems from different technical vocabulary and knowledge-base of air quality and transportation modelers.  State DOTs need guidance that can bridge the gap between air quality and traffic modelers by articulating air quality needs with an understanding of common language and tools available to traffic modelers. 

Research Objective:

The objective of this research is to supplement NCHRP Report 765, "Analytical Travel Forecasting Approaches for Project-Level Planning and Design" by providing guidance focusing specifically on generating traffic information for air quality analysis.  The guidance will aid traffic modelers in understanding the traffic data needed for air quality analysis. It will also contribute to improved accuracy and efficiency of the traffic and activity modeling required for federally required air quality analyses by providing guidance to modelers to help them develop data in formats that can be easily used by air quality analysts.  NCHRP Report 765 addressed the general subject of project-level modeling in detail but does not address needs specific to project-level air quality analyses. For more information on NCHRP Report 765, visit: https://www.trb.org/Publications/Blurbs/170900.aspx

The Quick Reference Guide describes traffic needs for project screening, refined analyses, and dispersion modeling of carbon monoxide (CO), particulate matter (PM), and mobile source air toxics (MSATs). Information on greenhouse gas (GHG) analysis is also included.


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