Carbon Monoxide Screen for Signalized Intersections: COSIM, Version 4.0: Technical Documentation

Illinois Carbon Monoxide Screen for Intersection Modeling (COSIM) Version 3.0 is a Windows-based computer program currently used by the Illinois Department of Transportation (IDOT) to estimate worst-case carbon monoxide (CO) concentrations near signalized intersections in Illinois. Modeled results from COSIM are based on the U.S. Environmental Protection Agency’s (EPA’s) mobile source emission model, MOBILE6.2, and roadway dispersion model, CAL3QHC v 2.0. Emission factor (EF) tables derived from MOBILE6.2 are incorporated directly into COSIM’s program coding. Recent regulatory changes in mobile source emissions modeling have prompted IDOT to update the EFs used in COSIM with EFs estimated using EPA's Motor Vehicle Emission Simulator (MOVES) mobile source emission model. This report documents the changes made to COSIM, Version 3.0, that allow IDOT to continue to use COSIM (Version 4.0) to estimate worst-case CO concentrations for proposed roadway projects with signalized intersections in 2013 and beyond.Illinois Department of Transportation R27-SP21published or submitted for publicationnot peer reviewe