Determine Alternative Calculations for Fine Particulate Emission Factors Other Than AP-42 Applicable to Calculate Re-entrained Dust on Transportation Projects
Research Idea Scope
TERI Administrator Note (June 2007): Funded as NCHRP Project 25-25, Task 42 http://www.trb.org/TRBNet/ProjectDisplay.asp?ProjectID=1660.
TERI Administrator Note (January 2009): Task reported completed Nov. 2008.
The US EPA emission factor document called “AP-42” provides emission factors for emissions of fine particulate from re-entrained dust on roadways. The way the calculations work, the amount of particulate (dust/silt loading) continues to increase with each passing vehicle. There is no higher limit on the amount of dust that can be created, even when there is only a finite amount of dust available on the roadway. The current tailpipe emission factor model, MOBILE6.2 does not account for re-entrained dust, so the options available to analysts are to either conduct expensive field monitoring to develop site specific emissions or use AP-42 emission factor calculations. The updated MOVES tailpipe emission factor model is also not anticipated to incorporate re-entrained dust emission factors.
The lack of upper limit for dust using AP-42 creates artificially high calculated emissions for transportation projects. To help PM10 and PM2.5 nonattainment and maintenance areas move forward with their transportation projects and provide more accurate data, states need a better tool to use for re-entrained dust calculations.
Identify more accurate, alternative calculation methods (or a more accurate modification of the existing AP-42 method) for fine particulate from re-entrained dust for both paved and unpaved roads that will be acceptable to the US EPA and states.
Conduct a literature search on currently available calculation methods of evaluation for re-entrained dust. Identify all viable field studies on re-entrained dust that used site-specific data. This search should not be limited only to the United States.
Compare the accuracy of calculation methods against known field studies.
Discuss the results of Tasks 1 & 2 with the project chair and steering committee to reach a consensus on scenarios of interest.
Develop draft guidelines on how well the calculations predict the measurements from field studies. Submit to the steering committee.
Make changes in response to committee comments and prepare final guidelines.
Mia Waters, Washington State Dept of Transportation 206/440-4541