A comparison of three modeling procedures—CAL3QHCR, AERMOD area, and AERMOD volume—for predicting pollutant concentrations near highways is presented. All three use the Gaussian dispersion equations and are evaluated by contrasting the trends in model predictions. Model trends are depicted for a variety of conditions related to atmospheric stability, wind angle with respect to the highway, and near-road downwind distances. The tested models provided widely differing prediction trends. Predictions by the CAL3QHCR model at the roadway edge for crosswind conditions were independent of atmospheric stability; however, AERMOD predictions varied significantly by atmospheric stability. AERMOD produced the highest pollutant concentrations at roadside with an area source configuration and the lowest with a volume source configuration. AERMOD predicted a wider range of concentrations across unstable to stable atmospheric conditions compared with CAL3QHCR. The concentration decay predicted by AERMOD for convective conditions was virtually identical across a wide range of atmospheric scaling (Monin-Obukhov lengths of −6.9 to −8,888 m).
EckhoffP. A., and BravermanT. N.Addendum to the User's Guide to CAL3QHC Version 2.0 (CAL3QHCR User's Guide).Office of Air Quality Planning and Standards, Technical Support Division, U.S. Environmental Protection Agency, 1995. http://www.epa.gov/ttn/scram/dispersion_prefrec.htm#cal3qhc.
3.
Air Quality Assessment Division, Office of Air Quality Planning and Standards. User's Guide for the AMS/EPA Regulatory Model—AERMOD. EPA-454/B-03-001. U.S. Environmental Protection Agency, 2004. http://www.epa.gov/ttn/scram/models/aermod/aermod_userguide.zip.
4.
VallamsundarS., and LinJ.Sensitivity Tests of MOVES and AERMOD Models for PM2.5 Hotspot Analysis. Presented at 2012 International Workshop on Mobile Source PM2.5 Emission Controls, Beijing.
5.
PaschA., BaiS., EisingerD., CraigK., AndrewsJ., and ElderJ.PM Hot-Spot Analysis Using AERMOD and EMFAC2011: Technical Issues and Lessons Learned. Presented at 91st Annual Meeting of the Transportation Research Board, Washington, D.C., 2012.
BensonP. E.CALINE3—A Versatile Dispersion Model for Predicting Air Pollutant Levels Near Highways and Arterial Streets. Report FHWA/CA/TL-79/23. Office of Transportation Laboratory, California Department of Transportation, 1979. http://www.epa.gov/ttn/scram/userg/regmod/caline3.pdf.
9.
Office of Air Quality Planning and Standards. User's Guide to CAL3QHC Version 2.0: A Modeling Methodology for Predicting Pollutant Concentrations Near Roadway Intersections. EPA-454/R-92-006R. U.S. Environmental Protection Agency, 1995. http://www.epa.gov/ttn/scram/dispersion_prefrec.htm#cal3qhc.
10.
Transportation and Regional Programs Division, Office of Transportation and Air Quality. Transportation Conformity Guidance for Quantitative Hot-Spot Analyses in PM2.5 and PM10 Nonattainment and Maintenance Areas. EPA-420-B-10-040. U.S. Environmental Protection Agency, 2010. http://www.epa.gov/otaq/stateresources/transconf/policy/420b10040.pdf.
Air Quality Assessment Division, Office of Air Quality Planning and Standards. Near-Road NO2 Monitoring Technical Assistance Document. EPA-454/B-12-002. U.S. Environmental Protection Agency, 2012. http://www.epa.gov/ttn/amtic/files/nearroad/NearRoadTAD.pdf.
13.
Office of Air Quality Planning and Standards, Office of Air and Waste Management. Application of the HIWAY Model for Indirect Source Analysis—User's Manual. EPA-450/3-75-072. U.S. Environmental Protection Agency, 1975.
14.
Office of Air Quality Planning and Standards, Office of Air and Waste Management. Guidelines for Air Quality Maintenance Planning and Analysis, Volume 9 (Revised): Evaluating Indirect Sources. EPA-450/4-78-001. U.S. Environmental Protection Agency, 1978. http://www.epa.gov/nscep/index.html.
15.
Office of Air Quality Planning and Standards. Guideline for Modeling Carbon Monoxide from Roadway Intersections. EPA-450/R-92-005. U.S. Environmental Protection Agency, 1992. http://www.epa.gov/ttn/scram/guidance/guide/coguide.pdf.
16.
Transportation and Regional Programs Division, Office of Transportation and Air Quality. Using MOVES in Project-Level Carbon Monoxide Analyses. EPA-420-B-10-041. U.S. Environmental Protection Agency, 2010. http://www.epa.gov/otaq/stateresources/transconf/policy/420b10041.pdf.
17.
ClaggettM.Improvements to the CAL3QHCR Model. Presented at 93rd Annual Meeting of the Transportation Research Board, Washington, D.C., 2014.
18.
PasquillF.The Estimation of the Dispersion of Windborne Material. Meteorological Magazine, Vol. 90, No. 1063, pp. 33–49.
19.
GolderD.Relations Among Stability Parameters in the Surface Layer. Boundary-Layer Meteorology, Vol. 3, 1972, pp. 47–58.
20.
ScireJ. S., StrimaitisD. G., and YamartinoR. J.A User's Guide for the CALPUFF Dispersion Model (Version 5).Earth Tech, Inc., Concord, Mass., 2000.
21.
Atmospheric Research and Exposure Assessment Laboratory. User's Guide to the Complex Terrain Dispersion Model Plus Algorithms for Unstable Situations (CTDMPLUS): Volume 1. Model Description and User Instructions. EPA/600/8-89/041. U.S. Environmental Protection Agency, 1989.
