The Illinois Department of Transportation (IDOT) currently uses the computer screening model Illinois Carbon Monoxide Screen for Intersection Modeling (COSIM) to estimate worst-case carbon monoxide (CO) concentrations that could result after the construction of proposed roadway projects affecting signalized intersections having traffic volumes of more than 16,000 average daily traffic (ADT). If the results from COSIM are within the National Ambient Air Quality Standards (NAAQS) for CO, no further CO modeling is required for the intersection. If the results from COSIM indicate that the project may cause a NAAQS violation, a detailed analysis is performed to more accurately evaluate potential CO levels. Modeled results from Version 1.0 and 1.1 of COSIM are based on the U.S. Environmental Protection Agency's (USEPA's) mobile source emission model, MOBILE5b, and roadway dispersion model, CAL3QHC v 2.0. In January 2002, the USEPA released an updated version of the MOBILE model called MOBILE6. The main objective of this research was to update the COSIM with new vehicle emission factors using MOBILE6. In addition to updating the emission factors used in COSIM, pre-screen criteria for determining when COSIM needs to be used for a roadway project were developed to replace the 16,000 ADT threshold. The new criteria were incorporated into the new release of COSIM as a Pre-Screen feature. This report summarizes the methods used to determine MOBILE6 emission factors and to develop revised pre-screen criteria. The report also documents the creation of a new version of the COSIM model designated as Version 2.0.


  • English

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: 102 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00962846
  • Record Type: Publication
  • Report/Paper Numbers: ITRC FR 97-6,, Final Report
  • Contract Numbers: IIIA-H1, FY 97
  • Files: TRIS
  • Created Date: Sep 11 2003 12:00AM