The Congestion Mitigation and Air Quality Improvement Program
A Summary of Eighth-Year Activities
(FY 1999) October 1998 - September 1999

Analysis of Air Quality Emission Benefits

Overall Analysis

Based on the State annual reports submitted to FHWA, the total number of proposals with accompanying emissions reductions analyses was 653 for VOC, 345 for carbon monoxide (CO), 575 for nitrogen oxides (NOx) and 52 for PM-10. The range of emissions reduction potential for each of the major transportation-related emission types is provided on the following pages as shown in Figures 3 through 6 (x-axis represents the number of projects and the y-axis represents kilograms per day).

Emission reduction estimates were provided for particulate matter emissions only for a limited number of projects, as has been noted in previous annual CMAQ reports. This is understandable since no federally approved method existed for the analysis of PM-10 emissions. In FY 1998, 99 CMAQ projects were reported as having quantified particulate matter reductions compared to 52 in FY 1999. Twenty-six of these projects were estimated to reduce less than 5 kilograms per day or less. However, 11 were estimated over 100 kilograms per day and three were estimated to produce benefits of over 1000 kilograms per day.

In addition to the projects that have emission reductions submitted for this year, there are two additional types of projects that do not have current reported benefits. They are termed the Qualitative Assessment and the Previously Reported projects.

Not every air quality beneficial proposal is able to have calculated numerical emission reductions. Some projects can logically be considered to have air quality benefits but not lend themselves to numerical quantification. Such proposals can be eligible for CMAQ funding if the project sponsor submits an acceptable description of how the project would lead to emission reductions. Such a description is called a Qualitative Assessment and, each year, there are a number of projects that become eligible for CMAQ support in this manner.

Many projects are large enough that they cannot be completed in 1 year or for other reasons are funded in phases over 2 or more years. Such projects have normally had their emissions benefits reported in their first year of funding (which is, in fact preferable, to avoid any possibility of double-counting). In subsequent years, they may not have their emission reductions re-reported. However, they are eligible for continued funding to accomplish their purposes. Thus, each year a number of projects are funded without having a new listing of emissions benefits.

Table 3 (below) provides an overview of the project benefit analyses submitted by the States according to category of proposal. As indicated in Table 3, a majority of proposals submitted for CMAQ funding have been reviewed for emissions reductions for smog-related pollutants (e.g., CO, VOC and NOx emissions).

As shown in Figures 3 through 6, the majority of proposals submitted under the CMAQ program have less than 5 kg/day emission reduction potential based on estimates provided by States in their annual CMAQ reports. Approximately half of VOC emission estimates provided by States (331 of 649 reporting VOC emissions reductions), yield 5 kg/day or less, and 91 percent yield less than 100 kg/day. However (as shown in Figure 4) a substantial number of CMAQ-funded proposals submitted with emission estimates for CO (23 percent) target emissions reductions in the 100 to 1000 kg/day emissions range, due primarily to the larger amount of CO emitted from the tailpipe relative to VOC or NOx emissions.

FIGURE 3 - Expected VOC Emissions Reductions (FY 1999)

FIGURE 4 - Expected CO Emission Reductions (FY 1999)

FIGURE 5 - Expected NOx Emission Reductions (FY 1999)

FIGURE 6 - Expected PM-10 Emission Reductions (FY 1999)

A summary (Table 4) provides an overview of the four major transportation-related pollutants in terms of the number of analyses, as well as minimum, maximum, and median ranges of emission reduction estimates provided by States in their FY 1999 annual reports. The range of minimum, maximum, and median emissions estimates are consistent with those estimates reported in previous CMAQ annual reports.

Table 5 (below) provides VOC emission information gathered from State CMAQ annual reports that suggests that the greatest median air quality emissions reductions occur in the demand management category. The lowest level of benefits reported is in the pedestrian/bicycle category. However, the emission reductions of these projects is comparable to others on average, and these are also the least expensive projects reported. Out of the 653 CMAQ proposals submitted with VOC emission reductions estimates, the traffic flow improvement category has the largest single share of projects (285) with quantitative estimates (median value of 4 kg/day VOC emissions removed from the atmosphere). The largest amount of VOC emissions reductions are associated with the "Other TCMs" category (e.g., enhanced I/M programs, etc.) as noted in previous CMAQ annual reports.

Table 6 (below) shows the emissions benefits of 345 CMAQ-funded proposals in kg/day of CO removed from the atmosphere. The category of demand management is shown to have the highest median value for CO (202 kg/day) significantly higher than the median estimates of CO reductions for other categories.

Table 7 (below) shows the minimum, median, and maximum emissions benefits for NOx based on data provided by States in their FY 1999 annual reports. Out of 575 CMAQ proposals submitted with NOx emissions reductions estimates, the category of projects with the most NOx emissions reductions estimates is again shown to be traffic flow improvements.

However, the highest median value of NOx emission reductions potential (20 kg/day) is again shown to be in the demand management category. In fact, the demand management category accounted for the highest median values in all three pollutant types shown in Tables 5-7, although the number of projects in this category is small compared to the others.

Table 8 (below) shows the emissions benefits of 52 CMAQ-funded proposals in kg/day of PM-10 removed from the atmosphere. The category of demand management is shown to have the highest median value for PM-10 (406 kg/day), but this should be discounted heavily since there was only one demand management project with a PM-10 estimate.

Table 9 (below) summarizes the top CMAQ-funded proposals with at least 500 kg/day VOC emission reduction potential based on data provided by States in their annual reports. As shown in this table the two projects resulting in the greatest VOC reductions were the same as reported in the FY 1998 report, which were related to enhanced I/M programs. The total number of CMAQ-funded proposals with at least 500 kg/day VOC emission reductions was found to be 13 for 1999, up one from FY 1998 and down three from FY 1997.

Areas Needing Improvement

Based on review of the State annual reports submitted for FY 1999, the following areas will need additional improvement as the CMAQ program evolves throughout its existence under the TEA-21. As found in previous reviews of State annual reports, additional efforts to provide more than minimal project descriptions would assist FHWA and FTA in the future. In some cases, project descriptions were found to be inadequate, and thus required follow up phone conversations to State and local officials to better identify the CMAQ projects and their potential air quality benefits. Also, the estimates of emissions benefits that were used to determine CMAQ eligibility for the projects should be submitted in the State reports.

This information is gathered to respond to Congressional inquiries and to support briefings to higher ranking Administration officials, and other major stakeholders which are routinely performed by FHWA/FTA. The basis for information provided is often derived from annual CMAQ reports submitted by States.