5
FINDINGS AND RECOMMENDATIONS

A summary of the key findings resulting from the committee’s assessment of the CMAQ program is presented in this chapter, and the committee’s recommendations for improving the program are provided. As discussed in Chapter 4, the supporting evidence for these findings and recommendations is largely qualitative, drawn from the committee’s review of program operations to date, the papers commissioned for this study, the case studies conducted by and briefings provided to the committee, and the committee’s understanding of the changing air quality and travel context in which the program operates.

SUMMARY OF FINDINGS

It is not possible to undertake a credible scientific quantitative evaluation of the cost-effectiveness of the CMAQ program at the national level. An evaluation of the CMAQ program must take into account the magnitude of the air quality problem in the United States and must also provide a realistic expectation of the influence one relatively small program can have on improving air quality. Pollution from transportation is only one of many sources of emissions; industry is also a major polluter. The CMAQ program is modestly funded and accounts for a small portion of any region’s transportation budget. Thus, evaluation of the effectiveness of the CMAQ program even at the local level is difficult because the effects of most CMAQ projects are small compared with those of other sources of variation in emissions and air quality. In addition, methods for measuring the effects of many CMAQ-funded projects on emissions and air quality are limited at present. The available models are not suited to estimating the emissions effects of small projects or linking these effects with air quality. Moreover, few evaluations have been conducted following



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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 5 FINDINGS AND RECOMMENDATIONS A summary of the key findings resulting from the committee’s assessment of the CMAQ program is presented in this chapter, and the committee’s recommendations for improving the program are provided. As discussed in Chapter 4, the supporting evidence for these findings and recommendations is largely qualitative, drawn from the committee’s review of program operations to date, the papers commissioned for this study, the case studies conducted by and briefings provided to the committee, and the committee’s understanding of the changing air quality and travel context in which the program operates. SUMMARY OF FINDINGS It is not possible to undertake a credible scientific quantitative evaluation of the cost-effectiveness of the CMAQ program at the national level. An evaluation of the CMAQ program must take into account the magnitude of the air quality problem in the United States and must also provide a realistic expectation of the influence one relatively small program can have on improving air quality. Pollution from transportation is only one of many sources of emissions; industry is also a major polluter. The CMAQ program is modestly funded and accounts for a small portion of any region’s transportation budget. Thus, evaluation of the effectiveness of the CMAQ program even at the local level is difficult because the effects of most CMAQ projects are small compared with those of other sources of variation in emissions and air quality. In addition, methods for measuring the effects of many CMAQ-funded projects on emissions and air quality are limited at present. The available models are not suited to estimating the emissions effects of small projects or linking these effects with air quality. Moreover, few evaluations have been conducted following

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 the completion of CMAQ projects to determine whether modeled estimates have been realized. Thus, the basic data needed to carry out a cost-effectiveness analysis are not available. Even if better data and analytic methods were available, it would be unrealistic to attempt a nationwide cost-effectiveness analysis of the CMAQ program. Regions have differing priorities for their use of CMAQ funds; some are more interested in congestion mitigation, others in air quality. Hence finding a common basis on which to measure program effectiveness is difficult. Moreover, the costs and effects of CMAQ-funded projects are highly location specific. They can vary greatly within one metropolitan area, not to mention among areas. The performance of a project in a given region depends on the transportation systems already in place, the air quality and congestion mitigation measures already implemented, and the projects (CMAQ-funded and others) implemented together with any CMAQ projects. Therefore, an infeasible number of local studies would have to be conducted to aggregate local results credibly into a national total. A broad range of regional transportation planners, operating agency staff, air quality officials, and interest groups consulted for this study see value in the CMAQ program and support its continuation. This conclusion is not surprising because the CMAQ program helps finance the mandates imposed on the transportation sector by the 1990 Clean Air Act Amendments (CAAA). It provides funds specifically to assist regions with poor air quality in reaching and maintaining conformity. Without this restriction, the money likely would go to other uses, such as the backlog of infrastructure rehabilitation and expansion needs. For many regions that have implemented most available pollution reduction strategies, CMAQ-funded transportation control measures (TCMs) offer an additional source of reductions that can help keep an area in conformity and within state implementation plan (SIP) emission budget targets. The CMAQ program also provides funds that can be used for a wide range of activities, enabling areas to tailor their projects and programs to address specific local air quality and congestion problems and priorities. The program affords great flexibility in comparison with many other transportation programs whose funds are restricted to specific programmatic areas (e.g., highways, bridges).

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 The complexity of transportation funding in general creates an incentive to try to tailor investment programs to available funds, instead of establishing funding priorities based on investment worthiness. Flexible funds are therefore of great value to regions. The CMAQ program provides regions with the incentives and opportunity to experiment with nontraditional transportation projects, particularly alternatives to highway projects that are popular among elected officials and citizens. Given the scarcity of available funding, this focus would probably not have occurred without the CMAQ program. The committee was unable to determine whether the CMAQ program had resulted in any measurable change in transportation funding priorities at the national level. The Intermodal Surface Transportation Efficiency Act (ISTEA), which authorized the CMAQ program in 1991, introduced major changes in transportation and funding arrangements. For example, ISTEA imposed the transportation planning requirements that complemented the conformity provisions of the 1990 CAAA and also ended the practice of including unfunded projects in transportation plans. It was not possible to segregate the impact of the CMAQ program from that of other elements of ISTEA because the program was one of many changes in funding policy made simultaneously. Thus, the committee was forced to conclude that the shifts in funding priorities since 1991 have had as much to do with these other changes as with CMAQ, a relatively small element of the ISTEA legislation. The CMAQ program has helped foster the participation of new groups in the transportation planning and project selection process, building partnerships among diverse groups and expanding the number of stakeholders involved in transportation. CMAQ has complemented other elements of ISTEA in this emphasis on a more participatory and inclusive transportation planning process. The CMAQ program has also encouraged more interagency consultation and cooperation as local transportation agencies have been forced to think seriously about strategies for reducing pollution and congestion in their regions. The CMAQ program provides an opportunity to measure the cost-effectiveness of individual projects or groups of projects at the local

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 level. Because of the variety and sometimes innovative nature of the projects funded, the CMAQ program constitutes a valuable laboratory for learning how well different types of projects perform in improving air quality and reducing congestion. To date, however, the evaluations that have been conducted have been of limited use. One reason for this is that none of the evaluations provide direct measurements of the primary final program outcomes—changes in pollutant concentrations and congestion levels. Another is that even the more sophisticated evaluations of necessity involve estimating such crucial effects as changes in traffic volumes or trips using models or inputs derived from models that were developed for regional analysis, and hence are too aggregate to capture the effects of highly location-specific projects. Some of these models, particularly emissions models, also have untested accuracy. Yet another problem is that most of the evaluations of TCMs are based on projected rather than actual outcomes. As a result of these problems, the levels of uncertainty of modeled estimates of project effects in some cases probably exceed the magnitude of the effects. Even when individual studies are reliable, it is difficult to make meaningful comparisons across projects because of differences in assumptions and methods. All these problems can be ameliorated with more attention to evaluation procedures. Thus, it is possible to make great improvements in the present ability to track the effectiveness of CMAQ projects. The limited evidence available suggests that, when compared on the sole criterion of emissions reduced per dollar spent, approaches aimed directly at emission reductions (e.g., new-vehicle emission and fuel standards, well-structured inspection and maintenance programs, and vehicle scrappage programs) have generally been more successful than most CMAQ strategies relying on changes in travel behavior (i.e., TCMs). The past record indicates that broad regulatory control strategies, such as new-vehicle emission and fuel standards, and other measures directly targeting vehicle emission reductions have generally been more cost-effective than attempts under the CMAQ program to change travel behavior. Nonetheless, the cost-effectiveness of some TCMs—those involving regional ridesharing, regional transportation demand management, and some pricing strategies—

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 compares favorably with that of non-CMAQ-eligible control strategies. There is considerable uncertainty about these conclusions, however. First, the comparisons are based on estimates of emission reductions for the ozone precursors only—volatile organic compounds (VOCs) and oxides of nitrogen (NOx)—because the data were generally not available for other pollutants. Had estimates of emission reductions for particulates and carbon monoxide (CO) been available, strategies focused on these pollutant sources (e.g., alternative-fuel buses) might have ranked more favorably. Second, the wide range of cost-effectiveness results for TCMs, even for the same type of CMAQ strategy, suggests that performance depends largely on context, that is, on where and how projects are executed. Third, many TCMs have benefits other than emission reductions (e.g., congestion mitigation, ecological effects). Finally, the estimates for nearly all strategies are affected by modeling uncertainties. Modeled estimates have generally tended to overestimate emission reductions. Inspection and maintenance programs provide a good illustration. Modeled results show such programs to be highly cost-effective, but a recent study (NRC 2001) revealed that the emission benefits are overestimated for many of these programs. Modeling uncertainties are compounded for TCMs, which require the prediction of travel as well as emission effects, adding to the uncertainty of the estimates. The CMAQ program encourages innovation and experimentation that can lead to the development of cost-effective projects. The program provides incentives and resources for local agencies to think seriously about new strategies for improving air quality and reducing congestion. With its focus on new facilities and services and its breadth of eligible nontraditional transportation projects, the program encourages local areas to experiment and provides the opportunity to fund small demonstration projects. If local areas can learn from the successes and failures of these efforts and share this learning widely, some of these projects may in time warrant broader implementation and leverage more traditional funding sources. The historical performance of CMAQ projects does not provide a basis for confident projections about the future cost-effectiveness of these projects. Since the CMAQ program was enacted in 1991, the vehicle fleet has gradually become cleaner as newer vehicles meeting

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 more stringent emission regulations have come to make up a larger share of the fleet, and alternative-fuel vehicles have become more common. These changes will alter the relative desirability and cost-effectiveness of different strategies. For example, they will probably make it increasingly difficult in the future to find projects that address both congestion and air quality. Traffic flow improvements undoubtedly had greater impacts when cars were “dirtier.” Automobile emissions are increasingly a function of the small number of dirty cars and of certain types of driving (e.g., hard accelerations, grades), a fact that enhances the value of such strategies as use of remote sensing and well-structured inspection and maintenance programs to detect and possibly repair heavily polluting vehicles, and vehicle scrappage programs designed to take these vehicles off the roads. Once cost-effective strategies have been applied in a nonattainment area, more stringent versions of these programs (e.g., enhanced inspection and maintenance, regional ridesharing) to achieve further emission reductions would probably be adopted only at much higher cost. Finally, new knowledge is emerging about the adverse health effects of pollutants, such as particulates and air toxics, that are not currently a program emphasis. Focusing more attention on strategies that address the primary transportation sources of these pollutants—heavy-duty diesel vehicles—may have important benefits. RECOMMENDATIONS The quantitative evidence reviewed by the committee on the benefits of the CMAQ program did not provide a strong basis for either supporting or opposing continuation of the program. Nonetheless, on the basis of its review of the available qualitative as well as quantitative evidence on program effectiveness, the committee reached consensus on the following recommendations. 1. The CMAQ program has value and should be reauthorized with the modifications recommended below. The potential benefits of the CMAQ program are sufficiently great, in the collective judgment of the committee, to warrant its continuation. This judgment is made despite the inadequacy of the data to support an overall quantitative cost-effectiveness evaluation, for the following reasons.

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 First, CMAQ is the only federally funded transportation program explicitly targeting air quality improvement. Arguably the most important benefits of the CMAQ program are the incentives and resources provided to local agencies to think seriously about strategies for improving air quality and reducing congestion. Second, the funds provided are restricted to these purposes, offering an opportunity for local nonattainment areas to experiment with nontraditional transportation approaches to pollution control, and to forge new partnerships and greater interagency cooperation in the development of such approaches. Third, some of the most promising TCMs in terms of cost-effectiveness (according to admittedly uncertain data) receive limited if any support from traditional transportation funding sources, and thus depend on CMAQ for a full exploration of that promise. Fourth, the program helps nonattainment and maintenance areas fund the strict mandates and pollution control schedules required by the 1990 CAAA. Finally, CMAQ provides a flexible source of funds that can be used for a wide range of activities tailored to local pollution and congestion problems. 2. Air quality improvement should continue to receive high priority in the CMAQ program. Although the formal justification for the program gives equal weight to congestion management and air quality goals, in fact the latter have been given higher priority. It is desirable to maintain this focus on air quality because congestion management is already addressed by the much larger share of highway funds spent on infrastructure. At the same time, congestion management projects may in many instances make important contributions to the improvement of air quality, and such projects should be supported by the program. However, the primary criteria by which the cost-effectiveness of these projects and more generally that of all CMAQ-eligible projects are judged should relate to the reduction of air pollution. The CMAQ program’s legislative restriction on projects involving construction of new capacity for single-occupant vehicle travel should also be maintained, given the uncertain effects of such projects on air quality and the availability of other funds for this purpose. 3. Consistent with maintaining a focus on the air quality dimensions of the program, state and local air quality agencies should be involved more directly in the evaluation of proposals for

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 the expenditure of CMAQ funds. Program regulations encourage consultation with state and local air quality agencies in the development of appropriate project selection criteria and the agencies’ involvement in project and program funding decisions. The case studies conducted by the committee suggest that some regions do involve air quality agencies in these ways, but often the agencies have a more limited role. Air quality agencies are expressly charged with reducing emissions of air pollutants and meeting national air quality standards. Moreover, at least in some regions (e.g., Southern California), air quality agencies have generally greater technical expertise than transportation agencies concerning current understanding of air pollution phenomena, emission control technologies, and the cost-effectiveness of various control approaches. Thus in many regions, the role of air quality agencies should be strengthened so they can become more meaningful participants in the CMAQ project review process. 4. The components of air quality addressed by the CMAQ program should be broadened to include, at a minimum, all pollutants regulated under Title I of the Clean Air Act. The CMAQ program is focused primarily on VOCs, NOx, and CO. This focus is too narrow in view of emerging knowledge of other pollutants and their adverse health effects. For example, it is incongruous that particulate matter (PM), now believed to pose a greater health hazard than any of the other criteria pollutants, is included in CMAQ only for project eligibility, not as part of the funding allocation formula. At a minimum, the eligibility criteria and allocation formula should include all pollutants regulated under the Clean Air Act, which would cover PM10, as well as sulfur dioxide and air toxics. Any changes to regulated pollutants, such as implementation of new standards for fine particulates (PM2.5), should automatically be reflected in the CMAQ eligibility criteria and funding formula. Inclusion of PM2.5 would encourage regions to use CMAQ funds to a greater extent for the support of projects involving heavy-duty diesel vehicles. Moreover, when U.S. policies are put in place to address carbon dioxide and other greenhouse gas emissions, projects focused on these emissions should also be considered for eligibility for CMAQ funding. The issues are sufficiently important and complex, however, that a separate funding program may be required.

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 5. Any local project that can demonstrate the potential to reduce mobile source emissions should be eligible for CMAQ funds. The CMAQ program should encourage metropolitan planning organizations (MPOs) to select and approve the most cost-effective local strategies available for reducing mobile source emissions. For example, on the basis of the review of vehicle scrappage programs provided in Appendix F and summarized in Chapter 4, these programs, which appear to be more cost-effective than many other types of projects routinely approved under the CMAQ program, should be eligible for CMAQ funding.1 Current restrictions on the use of public funds for private purposes should be reviewed to permit such programs. Regions should also consider wider use of CMAQ funds for projects focused on heavy-duty diesel vehicles and freight transport that can demonstrate the potential to reduce particulate emissions. 6. Restrictions on the use of CMAQ funds for operating assistance should be relaxed if it can be demonstrated that using the funds for this purpose continues to be cost-effective. The restriction on using CMAQ funds for operating expenses of newly initiated CMAQ projects for more than 3 years creates an incentive for making capital expenditures that may not be efficient, and may arbitrarily eliminate some cost-effective operating expenditures. For example, the best way to increase transit ridership may often be to reduce fares. At the margin, this measure could reduce trip making in old cars. The use of CMAQ funds to expand bus service generally results in highly subsidized service. When the operating subsidies are removed, the service often cannot be continued. The committee recognizes that not all operating subsidies are cost-effective or will continue to be so. Moreover, once projects have commenced, local pressures to continue them could increase if restrictions on the use of CMAQ funds for project operations are 1 A recently published dissertation on travel behavior, older vehicles, and vehicle scrappage programs (Dill 2001) provides a comprehensive assessment of such programs, including consideration of the roles and use of older vehicles in U.S. households. Dill finds that most vehicle scrappage programs reduce emissions significantly, particularly emissions of VOCs. It should be noted, however, that as vehicles become cleaner, it remains to be seen what emission reductions will be achieved and thus whether vehicle scrappage programs will continue to be cost-effective.

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 eliminated. Thus, the committee recommends that all proposed CMAQ projects—capital or operating—be evaluated through a process, outlined below, that should help establish the cost-effectiveness of proposed and funded projects. The use of CMAQ funds for operations should not be an entitlement and should be reviewed in competition with applications for other projects. 7. The use of CMAQ funds should be considered for land use actions designed to establish the conditions for long-term reductions in future mobile source emissions. The potential of land use strategies to reduce congestion or vehicle emissions is complex and unclear. There appears to be some evidence to support the link between urban design (i.e., the relative location of activity and housing, mixed-use design) and encouragement of travel modes other than the automobile (EPA 2001; Ewing and Cervero undated). Thus with further study, projects that support transit- and pedestrian-oriented development might be made eligible for CMAQ funding.2 Other land use actions—such as Portland, Oregon’s, revolving capital fund, which has been used to aggregate land in appropriate locations for sale to developers—could also be considered. 8. The agency responsible for CMAQ project selection in each nonattainment area should develop a process by which projects can be identified, selected, and evaluated in the context of the specific air quality and congestion problems of that region. In turn, the federal project approval process should be streamlined. The committee believes many nonattainment areas could do a better job of selecting projects for CMAQ funding that are linked more closely to the specific air quality and congestion problems of the region, and of developing the information needed to determine whether project and program objectives have been accomplished. For example, the lead agency responsible for the CMAQ program in a region could seek the advice of air quality agencies and public health 2 The Environmental Protection Agency (EPA) has prepared a guidance document (EPA 2001) that provides recommendations regarding the kinds of land use activities that can be accounted for in SIPs and conformity determinations. The document also presents a sketch planning model—EPA’s Smart Growth Index—that can be used to determine whether a particular land use activity may have air quality benefits (EPA 2001, 65).

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 experts in identifying the most effective pollution control strategies. It could also review the recommendations of the ISTEA-required congestion management plans that most urbanized areas larger than 200,000 in population must prepare to identify proposed strategies and steps already taken to address regional congestion problems. Once this context-setting effort has been completed, the lead agency could define objectives for its CMAQ program and develop measurable performance indicators so that individual project outcomes could be quantified. At a minimum, these indicators should include measures to estimate emission reductions, but it would also be desirable to define and measure other effects, such as congestion mitigation and, where appropriate, effects on ecosystems or economic development. The intent of this structure is not to add a new layer of regulatory requirements, but to build on and strengthen the existing transportation planning and certification process. With greater ability to measure program performance against objectives, responsible local agencies should be in a better position to document the effects of CMAQ projects, report on those effects to their constituencies, and provide more complete input to FHWA’s national CMAQ database that could be used for evaluation purposes. Once a nonattainment area has implemented a process along the lines just described, determinations of project eligibility by federal program sponsors should no longer be required. Projects should be precertified as long as a region can demonstrate that they are consistent with the program objectives outlined above. Of course, all National Environmental Policy Act requirements would still need to be addressed if applicable to specific projects. 9. Recipients of CMAQ funds should be given incentives to conduct more evaluations of funded projects, and federal program sponsors should provide guidance on best practices for these evaluations. One of the greatest benefits of the CMAQ program may well be the development of new strategies that can be adopted by other localities or incorporated into subsequent federal legislation. This benefit is now largely lost because there is no reliable way to gauge the success of different strategies. Local agencies are currently required to provide information on the expected emission reduction potential of

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 funded projects for the FHWA database, but evaluation of the effects of implemented projects is not required. Recipients of CMAQ funds should be expected to conduct more follow-up to determine whether the anticipated reductions have been realized and examine the factors that have made a project successful. The committee realizes it would be impractical for a region to evaluate all its CMAQ projects. Likely candidates include individual projects that are expensive or controversial and groups of small projects (e.g., bicycle projects or traffic signal improvements) that together have measurable effects. For example, the Chicago MPO—the Chicago Area Transportation Study (CATS)—undertook an evaluation of CMAQ-funded bicycle projects that proved quite beneficial in evaluating and selecting among bicycle projects for future CMAQ funding. The evaluation consisted of a survey conducted by CATS staff of bicycle riders on bicycle paths that had been funded by CMAQ. Riders were asked (a) the purpose of their trip (e.g., commuting, recreation), (b) the length and destination of the trip, and (c) the alternative mode of transportation that would have been taken, if any, had the bicycle path not been built. The results of the survey helped CATS staff identify bicycle path locations that attracted commuters rather than recreational bikers, determine whether bicycle trips replaced trips by car, and develop estimates of the emission reductions attributable to those trips. FHWA, in consultation with EPA, should provide program recipients with guidance on best practices for conducting such evaluations, including examples and contacts for additional information. Two recent initiatives by FHWA are a start in the right direction—the primer describing modeling tools and other analytic methods that can be used to assess the potential emission benefits of CMAQ project applications (Louis Berger Associates 2000) and the development of a 2-day course on the CMAQ program for state and local program recipients. The latter course includes treatment of evaluation methods such as before-and-after analysis, estimation of emission reductions and other performance measures for candidate projects, and case studies (FHWA 2001). Although program recipients might prefer that all CMAQ funds be reserved for projects, evaluation is in the interest of both federal

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 sponsors and local recipients, and thus is an entirely appropriate use of CMAQ funds. The best incentive to encourage more local project evaluation would be to provide additional funds for this purpose. 10. A more targeted program of evaluation should be undertaken at the national level, to include in-depth evaluation studies, synthesis and dissemination of results, research on appropriate analysis methods, and monitoring. The CMAQ program offers a rare opportunity to evaluate a diverse group of implemented projects whose primary purpose is to improve air quality and reduce congestion. Little systematic evaluation has been undertaken, even though TCMs were widely employed well before the CMAQ program was established. This lack of evaluation is partly the result of the intrinsic difficulty of predicting or measuring the effects of strategies that cause only small changes in emissions, air quality, and travel costs. Models are under development that should provide for more accurate assessments of the travel variables and emission levels affected by TCMs, and methods are being devised to measure changes in emissions and pollutant concentrations at the tailpipe directly. FHWA, in consultation with EPA, should take the lead in initiating a well-focused national program of evaluation financed by CMAQ funds set aside for this purpose. The program would fund a selected group of studies—perhaps drawing on a representative sample of CMAQ projects both within and across regions—in which competitively selected researchers would work with local agencies to collect baseline data and track project performance using credible evaluation criteria. FHWA or EPA should synthesize the results of these studies and maintain a cumulative database for their broad dissemination. Appropriate research designs, methods, and models for conducting evaluations of difficult-to-measure TCMs are also appropriate topics for study, but CMAQ should not be the sole funding source for this purpose because the results will have application well beyond the program. For example, the appropriate geographic or programmatic scale at which measurements should be carried out is not always evident. Such questions must be addressed as what geographic boundaries are appropriate for measuring the impacts of a traffic flow improvement project that include the effects of induced travel,

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 and whether it would be better to group small projects for analysis instead of evaluating their effects separately. The program should also include a monitoring component to help program sponsors remain abreast of the relevant science. Topics addressed might include, for example, human health effects and exposure assessment research concerned with in-vehicle and near-roadway exposure, as well as ecological effects of vehicle emissions and other secondary impacts. CONCLUDING COMMENTS Since its inception, the CMAQ program has provided nonattainment areas with a modest but valuable source of funds dedicated to addressing their air quality and related congestion problems. The program has offered incentives for regions to develop effective local pollution control strategies, drawing from a wide range of eligible projects. It has also encouraged broad participation by local agencies and public interest groups in strategy development, and has enabled them to experiment with nontraditional and innovative approaches. If the program is reauthorized in line with the above recommendations, the committee believes its sponsors should be in a better position in the future to account for the cost-effectiveness of implemented projects, evaluate the success of different strategies, monitor advances in scientific knowledge, and share this information widely among program recipients and the general public. REFERENCES Abbreviations EPA U.S. Environmental Protection Agency FHWA Federal Highway Administration NRC National Research Council Dill, J. 2001. Travel Behavior and Older Vehicles: Implications for Air Quality and Voluntary Accelerated Vehicle Retirement Programs. Dissertation. University of California, Berkeley. EPA. 2001. EPA Guidance: Improving Air Quality Through Land Use Activities. EPA420-R-01-001. Office of Transportation and Air Quality, Jan.

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The Congestion Mitigation and Air Quality Improvement Program: Assessing 10 Years of Experience - Special Report 264 Ewing, R., and R. Cervero. Undated. Travel and the Built Environment— Synthesis. FHWA. 2001. Congestion Mitigation and Air Quality Training Development. Request for Proposal Solicitation Notice DTFH61-02-R-00014. U.S. Department of Transportation, Oct. 30. Louis Berger Associates. 2000. A Sampling of Emissions Analysis Techniques for Transportation Control Measures. Final Report. Cambridge Systematics, Inc., for FHWA, U.S. Department of Transportation. Oct. NRC. 2001. Evaluating Vehicle Emissions Inspection and Maintenance Programs. National Academy Press, Washington, D.C., July.

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