The Clean Air Act of 1990 requires that transportation plans programs and projects not cause or contribute to violations of the health based air quality standards. This requirement met through the conformity process during which emissions from the transportation system are compared to emissions budgets in the State Implementation Plan. Without a conformity determination all regionally significant capacity additions are stopped. Historically the conformity process has dealt mostly with urban areas and urban area transportation plans. Once the eight-hour ozone standard is implemented conformity will required in a large number of rural areas. While many of these areas are contiguous with urban areas their transportation problems are different from those of urban areas. Under the current conformity regulation these new rural areas would be added to urban areas in order to implement the conformity process.
Departments of transportation should institute research intended to answer the following questions:
1. What are the appropriate institutional arrangements for performing conformity in rural areas?
2. What changes should be made in the conformity regulation which would make it possible to effectively make conformity determinations in rural areas?
3. What methods, other than travel demand models, are available to estimate regional emissions in rural areas?
The objective of this task is to survey DOT's and MPOs across the country who have experience with conformity in rural areas and determine what institutional, decision making, and analytical methods they have used in their conformity analyses and prepare a list of recommended procedures and methods for performing conformity in rural areas.