Updating the Illinois Carbon Monoxide Screen for Intersection Modeling (COSIM)
Background: IDOT uses the computer screening model Illinois CO Screen for Intersection Modeling (COSIM) to estimate worst-case carbon monoxide (CO) concentrations for proposed roadway projects affecting signalized intersections. 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 required to more accurately evaluate potential CO levels. The original model was developed in 1999 as part of an Illinois Transportation Research Center (ITRC) research project. In 2007, regulatory changes in the Illinois Vehicle Inspection and Maintenance (I&M) program prompted the Illinois Environmental Protection Agency (IEPA) to recommend that IDOT update COSIM with new emission factor (EF) tables generated from U.S. EPA's mobile source emission model, MOBILE 6.2.
Research: This project facilitated the release of COSIM Version 3.0 in June 2008. Version 3.0 incorporates new emission factors for Illinois On-board Diagnostics-only Vehicle Inspection and Maintenance program, enhancements to the pre-screen feature, and other updates.
Impact: Version 3.0 of COSIM is being used by IDOT to accurately predict CO concentrations.
PI: Scott Peters
