Synthesis of Current Practices in Traffic Microsimulation for Project-Level Air Quality Studies

Focus Area

Air Quality


Air Quality




Under $99k


Under 1 year

Research Idea Scope

The objective for this study would be to compile information on the state of the practice among state DOTs for using microscopic traffic simulation in support of project-level air quality studies for NEPA and conformity. It would answer questions such as to what extent are the simulation models being used to generate traffic forecasts for air quality studies, what parameters are being generated for use in air quality studies, e.g., queue lengths, speeds, volumes, drive cycles, operating mode distributions, etc., and what issues or challenges have been encountered and how they were handled. The time and cost for analyses of varying scope and complexity would also be documented for future reference. To the extent feasible based on the information obtained, the study may also recommend best practices.

For background, traffic simulation is a rapidly evolving field that holds significant promise for improving emission and dispersion modeling for air quality studies for NEPA, particularly as the models improve and costs are reduced. A synthesis study would help state DOTs remain abreast of the current state of the practice and position themselves to best make use of simulation modeling tools to support air quality studies in the future.

Urgency and Payoff

State DOTs would benefit through the use of improved traffic forecasts for emission and dispersion modeling. Such improvements are needed to support air quality studies for NEPA particularly in cases where margins between background concentrations and the applicable national ambient air quality standard (NAAQS) are small and accuracy in modeling is at a premium.

Suggested By

Christopher Voigt

[email protected]