NCHRP Report 462, Quantifying Air-Quality and Other Benefits and Costs of Transportation Control Measures,presents potential improvements to the analytical framework for assessing the air quality and other benefits and costs of transportation air quality control strategies. Short- and long-range improvements are included that will enhance the metropolitan planning models being used and considered in major metropolitan areas. The report also discusses how a monitoring program can augment quantitative analysis to provide a fuller understanding of the air quality impacts of transportation control measures. Air quality specialists will find the report helpful, particularly when considering improvements to their analysis systems. A CD-ROM containing more detailed research results is included with the printed report which is available at https://www.trb.org/trb/bookstore/.

The Clean Air Act Amendments of 1990 (CAAA) identify transportation control measures (TCMs) that are expected to provide emission-reduction benefits and other measures intended to modify motor vehicle use. In addition, depending on the area's nonattainment status, the CAAA mandates implementation of some of them. States and MPOs require specific, quantitative information on the benefits, costs, and expected air-quality improvements of various TCMs in order to select those TCMs that will best meet agency needs.

Under NCHRP Project 8-33, Cambridge Systematics evaluated current analysis techniques for estimating the impacts of TCMs on emissions. The research team then developed and tested a comprehensive framework for analyzing TCMs, including those designed to produce mode shifts, operational traffic changes, and reductions in motor vehicle usage. The testing used data from Sacramento, California, and Portland, Oregon. The framework is also useful for assessing other types of benefits and costs.

Cambridge Systematics also examined how air quality monitoring could augment emissions analysis in determining the effectiveness of TCMs. This effort consisted of a thorough assessment of the issues and a careful analysis of the transportation and measured air quality changes associated with the 1996 Olympic Games in Atlanta, Georgia. The report summarizes the research conducted and presents a list of recommended improvements to those modeling methods that are in common use. Priorities are assigned to each improvement based on its importance to TCM analysis and the ease of implementation. The report describes alternative methods of monitoring air quality and assesses their appropriateness for evaluation of TCMs. Findings from throughout the research effort are included to promote better understanding of the issues.

In the interest of brevity, considerable technical material has been consigned to a companion CD-ROM included with the printed report. The CD-ROM contains the following documents:

• Appendix A: Portland Pilot Testing
• Appendix B: Analytical Framework for the Evaluation of Air Quality Transportation Control Strategies
• Appendix C: Summary of Ambient Air Measurement Evaluation Studies
• Interim Report: Feasibility of Using Advanced Air Quality Monitoring Systems
• Interim Report: Use of Remote Sensing and Personal Exposure Monitors
• Interim Report: Relationships Between Monitored Air-Quality and Traffic During the Atlanta Olympics
• Interim Report: Freeway Speed Correction Factors
• Interim Report: Immediate Improvements to Current Analysis Techniques
• NCHRP Research Results Digest 217: Relationships Between Implemented Transportation Control Measures and Measured Pollutant Levels
• NCHRP Research Results Digest 223: Development of an Improved Framework for the Analysis of Air Quality and Other Benefits and Costs of Transportation Control Measures
• NCHRP Research Results Digest 230: Review of Travel Assumptions Employed in Emission Factor Models