Traditional air quality planning and conformity analysis consider only the total mobile emissions for a region, perhaps supplemented by the study of a few specific hot-spots. A new GIS-based tool, AQ+, was developed to implement instead a link-based approach, which allows planners to exploit GIS to examine and compare mobile emissions at the corridor level. AQ+ has been applied successfully in several cities, including Knoxville, Tennessee, Lexington, Kentucky, and Evansville, Indiana. The new tool eliminates significant aggregation bias in the traditional approach, resulting in more accurate emissions forecasts, and offers clear advantages for planning, enabling planners to prioritize air quality needs within a region and better allocate CMAQ and other air quality funds among competing projects. The paper presents the motivation for and implementation of this alternative approach. It explores challenges, advantages and limitations of an automated application of the MOBILE6 emissions model to the link-level output of a travel demand model, rather than its aggregate output and the way in which the GIS environment can facilitate the analysis, interpretation and presentation of the results.
Abstract