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SAFETEA-LU Evaluation and Assessment Phase I

2. Study Approach

As noted previously, this evaluation responds to a desire by Congress to better understand the direct and indirect impact of CMAQ projects on air quality and congestion levels after more than 15 years of experience. Congress also wanted to ensure the effective implementation of the program, make sure the DOT maintain and disseminate a cumulative database of annual CMAQ reports and that the DOT and EPA consider recommendations to improve the operation and evaluation of the CMAQ program.

The study team determined it was best to approach the request in two phases. This Phase I report is intended to satisfy the understanding of the air quality and congestion benefits of a sample of CMAQ projects. To conduct the evaluation, a small set of CMAQ projects was chosen, background data were collected, and analysis was conducted to determine the effects of these projects on emissions and on congestion levels. In addition, the research team collected data on the costs of these projects – both from CMAQ funding and other funding sources – and conducted additional analyses to assess the cost-effectiveness of the sample projects at reducing emissions of each pollutant. In Phase II, FHWA, in consultation with EPA, conducted case studies of several States and metropolitan areas to understand project analysis, selection, and prioritization procedures.

This section describes the approach to selecting the CMAQ projects and collecting data used in the Phase I study.

Project Categories and Distribution

The research team attempted to select a set of projects for evaluation that would reflect typical projects funded through the program. As noted earlier, the CMAQ program has traditionally organized projects into several large categories. Figure 1 presents a breakdown of the number of CMAQ funded projects by these major categories for FY 2000 to FY 2005.

Figure One Pie Chart.
Figure 1. Share of CMAQ Projects Obligated FY 2000 to FY 2005 by Project Category.

Figure 2 presents a breakdown of the percentage of total CMAQ funding received by projects in these major categories for FY 2000 to FY 2005.

Figure Two Pie Chart
Figure 2. Percentage of CMAQ Funding FY 2000 to FY 2005 by Project Category.

As can be seen from these two diagrams, transit and traffic flow improvement projects together made up over half the total number of projects funded and received nearly three-quarters of total funding. Transit projects, in particular, made up a larger share of funding than share of projects because many transit projects were larger in scale and involved more capital funding (e.g., vehicle purchases, new transit lines, etc.). In contrast, pedestrian/bicycle projects made up a smaller share of funding than their proportion of total projects since these projects tended to be small and involved less funding per project.

In developing a set of projects for analysis in this study, the CMAQ projects were organized into the major categories that FHWA has traditionally used to group CMAQ projects in its database. Subcategories were broken out where categories are larger and diverse, and additional categories were created for project types that currently are the focus of additional attention (e.g., diesel engine retrofits, freight/intermodal projects).

Given that more than half the projects funded by CMAQ over this period were either traffic flow improvements or transit projects, the study team determined that in order to ensure an adequate number of projects across the various project categories, the number of projects analyzed in each category would not be proportional to the number of funded projects or total funding by category. Rather, to ensure a reasonable number of projects across all categories, the study team endeavored to include a minimum of three projects within each subcategory. Larger samples were included for categories that historically have had more CMAQ projects funded or that are currently the focus of additional attention. In two cases (High-Occupancy Vehicle Lanes and Conventional Bus Replacements), fewer projects were collected, due to data limitations and relatively few projects that have been funded in recent years for these types of projects.

Table 1 illustrates the project categories and subcategories, and the number of CMAQ projects that were analyzed.

Table 1. CMAQ Projects Included in the Study by Project Category and Subcategory.
Category Subcategory Number of Projects
Traffic Flow Improvements Traffic Signalization/ Intersection Improvements 6
Freeway Management 4
High-Occupancy Vehicle Lanes 1
Shared Ride Programs Regional Ridesharing 3
Vanpool Programs 4
Park and Ride lots 5
Travel Demand Management   4
Bicycle/Pedestrian Projects   4
Transit Service Improvements New Bus Services 3
New Rail Services 3
Service Upgrades/Amenities 5
Transit Vehicle Replacements and Related InfrastructureConventional Bus Replacements   2
Alternative Fuel Vehicles/Fueling Facilities 4
Dust Mitigation   3
Freight/Intermodal   6
Diesel Emissions Reduction Diesel Engine Retrofits 7
Truck Idle Reduction 3
Total 67

Project Selection Procedures

Once the broad organization of projects was determined, a screening analysis based solely on information contained in the CMAQ database was conducted. The CMAQ database is a tool developed by FHWA to capture information about CMAQ projects, including funding information, emissions reduction estimates, the MPO, nonattainment or maintenance area, and a brief project description.

The process of selecting a small set of projects for analysis focused on identifying entries in the database which met the following selection criteria:

In addition to the above selection criteria, the initial screening focused largely, but not exclusively, on States that are apportioned the highest levels of CMAQ funding. This was done to achieve a representative sample of projects, since these States fund a larger number of projects; also, staff within these States would be able to provide information on more projects per contact should follow-up be needed. (See Table 2 for a list of States with the largest CMAQ apportionments over the period FY 1991 to FY 2005, along with the amount obligated.) A final consideration was the overall geographic diversity of the sample, and balance between large projects and small projects. The CMAQ funds received by the selected projects ranged in scope from $33,000 for a signal synchronization project in Tennessee to $36.2 million for a transit improvement project that involved double tracking segments of a commuter rail line between Dallas and Ft. Worth. In some cases, CMAQ funded only a small portion of the total project costs, helping to leverage other Federal (specifically, FTA) or state and local funds; this was the case in particular for some of the larger transit projects and HOV project. In many other cases, CMAQ provided the majority or sole source of funding.

Table 2. States Receiving Largest CMAQ Apportionments, FY 1991 – FY 2005.
State Amount Apportioned
(Million $)
Amount Obligated
(Million $)
California $ 4,019.1 $ 3,637.8
New York $ 1,698.6 $ 1,401.7
Texas $ 1,469.8 $ 1,208.7
New Jersey $ 1,084.2 $ 987.4
Illinois $950.1 $ 817.1
Pennsylvania $ 858.8 $ 821.2
Ohio $ 774.8 $ 731.5
Maryland $ 614.2 $ 539.9
Massachusetts $582.1 $ 475.7
Florida $521.2 $ 506.0
Michigan $ 478.5 $ 427.1
Connecticut $ 476.9 $ 434.4
Georgia $ 445.1 $ 387.5
Arizona $ 412.2 $ 381.6

Source: Memo from April Marchese, Director, Office of Natural Environment to FHWA Division Administrators on March 23, 2007 Available online at:

Data Collection Procedures

After using the project selection criteria identified above to identify a reasonable set of projects from the CMAQ Database, a combination of methods was used to gather missing or incomplete information on the selected projects. For example, Internet searches were conducted to find project-specific information that might be available online, as well as to obtain the contact information for the State or MPO CMAQ representative. In several cases, information on CMAQ projects was available from Transportation Improvement Program (TIP) reports, congestion mitigation reports, and posted evaluation reports online.

If data were still missing and accurate contact information could be obtained, CMAQ representatives at the State DOT or MPO were contacted. Representatives were provided information on the purpose of the evaluation project and the specific CMAQ ID numbers of interest, and were asked for reports on the emissions reduction methodology originally used to calculate the emissions benefit, project cost information, and any available project evaluations. A list of the State and local project sponsors consulted for backup information for this report is listed in Appendix A.

In several cases, initial projects for which data and methodologies were gathered were eliminated from the study. This occurred due to limited or incomplete documentation of assumptions, which made it difficult to determine how precisely the emissions benefits were calculated; or due to assumptions that appeared unusually high or low and did not appear to be representative of typical projects within the project category. In a couple of cases, it was found that the project sponsor incorrectly calculated emissions effects based on the documentation provided (i.e., due to a mathematical error, or improper conversion). In these cases, the reported values were corrected.

Once missing or incomplete CMAQ reports, TIP reports, and/or emissions calculations were provided by the local representative to supplement data from the CMAQ database, the data were entered into individual project "templates." These one-page project profiles are designed to capture in one place all the critical facts, such as calculated travel impacts, emissions factors used, and the non-Federal and Federal costs related to the example. The individual profiles for each of the CMAQ-funded projects analyzed in this report can be found in Appendix C.

In selecting projects for inclusion in this study, emphasis was placed on profiling to the fullest extent possible, the costs, impacts on congestion and air quality, and other benefits for each project. While the selected projects are intended to be representative of typical CMAQ-funded projects, the emissions effects and congestion effects estimated for these projects are not statistically significant indicators of the effects of projects that have been funded through the CMAQ program.

  1. Table of Contents
  2. Executive Summary
  3. Section One
  4. Section Two
  5. Section Three
  6. Section Four
  7. Appendix A
  8. Appendix B
  9. Appendix C
  10. Appendix D
Updated: 3/31/2014
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