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OCR for page 15
15
FIGURE 9 New York MTA GHG emissions by source, 2007 (draft) (Source : Greening Mass Transit
& Metro Regions: A Synopsis of the Final Report of the Blue Ribbon Commission on Sustainability
and the MTA , Metropolitan Transportation Authority, State of New York, Feb. 2009, p. 22).
While transit vehicles account for the majority of energy are attributed to nonrevenue vehicles (see Figure 9). Many
used by a typical transit agency, buildings are also important employees of transit agencies emit GHG emissions from
consumers of energy. Of the 2.7 MMtCO2e emitted by the their own vehicles as they commute to and from their jobs,
New York Metropolitan Transportation Authority (NYMTA) although these emissions may or may not be attributed to
in 2007, 18% are attributed to electricity and heating in the the agencies themselves.
agency's facilities, stations, and maintenance yards. Figure
9 illustrates the sources of the agency's emissions. Traction
energy, or energy used to propel transit vehicles, accounts for NET IMPACT OF U.S. TRANSIT ON GREENHOUSE GAS
EMISSIONS
79% of emissions. All other energy is considered nontrac-
tion. NYMTA's inventory does not include embodied emis-
sions related to the agency's vehicles and infrastructure. Four recent studies have estimated the net amount of GHG
emissions that U.S. transit services save each year. All have
Construction and Maintenance found that American public transit significantly reduces
GHG emissions from the transportation sector. Each of the
Depending on the modes used, transit systems may require studies accounted for the travel mode shift effect of tran-
significant construction efforts. Rail systems are the most sit and for transit vehicles' emissions. Some of the studies
construction intensive, often requiring that miles of new track also accounted for the compact development and conges-
and new stations be constructed as systems are initiated or tion mitigation effects of transit. Reductions range between
expanded. Transit agencies also construct and maintain bus 6.9 MMtCO2 and 36.6 MMtCO2, depending on the scope of
stations, bus shelters, and park-and-ride lots. Construction displaced emissions considered. For comparison, emissions
and maintenance of all transit offices, facilities, and infra- from all on-road transportation in the state of Washington in
structure use energy and produce GHG emissions: 2005 totaled 32.3 MMtCO2e (15).
· From on-road transportation of materials, construction Table 2 provides the results of individual studies. Esti-
workers, and waste; mates of mode shift and congestion reduction impact are
· From construction equipment; and similar across the studies. Of the two studies that estimated
· Emissions embodied in any materials used. the impact of compact development, the study by ICF Inter-
national calculates the greatest reduction. The statistical
Other Emissions technique used by ICF to capture land use effects of transit is
more comprehensive than that used in the California's Public
Transit agencies also maintain nonrevenue vehicle fleets Interest Research Group (CALPIRG) study (see chapter five,
used for maintenance and local travel. These vehicles Compact Development for more information). The results of
emit GHGs as well. At NYMTA, 3% of GHG emissions the CALPIRG study are buoyed by two other factors:
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TABLE 2
AGGREGATE GHG REDUCTIONS FROM PUBLIC TRANSIT IN THE UNITED STATES
Emissions Impact (MMtCO2)
Congestion Compact Transit
Study Author Study Date Mode Shift Net
Reduction Development Emissions
ICF Intl. 2008 -15.8 -3.0 -29.9 12.1 -36.6
CALPIRG 2008 -- -- -- -- -25.8
Shapiro et al. 2002 -16.5 N/A N/A 9.1 -7.4
SAIC 2007 -16.2 -3.0 N/A 12.3 -6.9
Sources: Bailey et al., The Broader Connection between Public Transportation, Energy Conservation and Greenhouse Gas Reduction,
ICF International, 2008 (10); Davis and Hale, Public Transportation's Contribution to U.S. Greenhouse Gas Reduction, Science Appli-
cations International Corporation, 2007 (4); Baxandall et al., A Better Way to Go: Meeting America's 21st Century Transportation
Challenges with Modern Public Transit, California's Public Interest Research Group Education Fund, 2008 (16); Shapiro et al., Con-
serving Energy and Preserving the Environment: The Role of Public Transportation, 2002 (7).
Note: Figures from the ICF study are calculated from figures in Tables 2 and 3 in that report using a conversion of 1 billion gallons of
gasoline = 8.8 MMtCO2. A dash (--) indicates that separate figures were not provided. N/A indicates that the effect was not included in
the calculation.
1. CALPIRG did not include demand response services, on analysis of a sample of 503 U.S. transit systems, the
which tend to be inefficient in GHG emissions, in its CALPIRG study concluded the following:
estimate. The authors reasoned that including demand
response in the estimate would mask the benefit of · Rail transit systems reduce emissions the most, in large
fixed-route services. part because of the land use impacts of rail in dense
urban settings, and because of the use of electricity as
2. CALPIRG estimated lower emissions from electric a transportation fuel.
transit vehicles in some regions, because it accounted · Bus systems have smaller, but still important impacts
for regional variations in sources of electricity. The to reduce GHG emissions.
other studies assumed an average national mix of · Vanpool programs provide relatively high savings on a
electricity generation. per passenger basis.
· Even most small transit agencies also provide GHG
Results also vary between the studies depending on the savings (16 ).
year of data used and modes included. For example, the Sha-
piro study (7 ) used older data than the other studies, and From a sample of 50 of the largest transit agencies, the study
included only bus and rail modes. found that agencies' impacts ranged from a net reduction of
10.5 MMtCO2 per year to a net increase of 0.07 MMtCO2 per
Individual transit agencies have different net impacts on year. Only one agency produced a net increase in GHG emis-
GHG emissions, depending on their sizes, types of service, sions. Appendix C provides estimates from CALPIRG of the
fleets, sources of energy, and operating parameters. Based impact of individual transit agencies on GHG emissions.
