Project-Level Air Quality Assessment Actions: Interrelating Conformity with National Environmental Policy Act Process

The procedural aspect of linking the transportation conformity process and the transportation alternatives development process that is part of the National Environmental Policy Act (NEPA) is discussed. The linkage is structured to ensure continuity between project-level design considerations developed during planning and programming and refined as part of the NEPA process. These issues are critical to the Pennsylvania Department of Transportation, Bureau of Environmental Quality, where air quality impacts delineated during the conformity process play a significant role in the continued development and refinement of the transportation system. For states like Pennsylvania, where transportation conformity requirements play a strong role in the transportation development process, providing a single set of air quality assessment actions can avoid the risk of conformity reevaluation or failure caused by project redesign during the NEPA process. A method to link the regional transportation conformity air quality analysis with project development and design conducted during the NEPA process is described. The linkage is made by using project-level air quality impacts developed during the regional conformity analysis and comparing the air quality impacts of transportation alternatives as they are developed during the NEPA process. Elements of the air quality impacts delineated during the regional conformity analysis act as the project-level air quality benchmark that is carried forward into the NEPA process.