An Update on Public Transportation's Impacts on Greenhouse Gas Emissions (2021) / Chapter Skim
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Pages 36-46
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From page 36... ...
36 To allow readers to walk through the analytical steps used, this appendix provides details of the public transportation GHG analysis summarized in the main body of the report, including calculation formulas and reference tables for the GHG emissions factors used in the assessment. Vehicle Typology The NTD provides transit data by mode names and vehicle types.
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GHG Analysis Methodology 37 Activity Data The activity data used to calculate emissions from transit revenue vehicles are the energy use data and vehicle mileage data reported in the NTD. The most recent data year at the time of the analysis was 2018.
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38 An Update on Public Transportation's Impacts on Greenhouse Gas Emissions Fuel Use (Gallons and kWh) Bus Commuter Rail Ferry Heavy Rail Light Rail Van Total Biodiesel (gallons)
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GHG Analysis Methodology 39 The authors used service and vehicle inventory data as reported by reduced reporters in the NTD to estimate the energy use and emissions of those systems based on the performance indicators calculated from the full reporters. Energy use and passenger miles were estimated for 384 reduced and other reporter transit agencies.
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40 An Update on Public Transportation's Impacts on Greenhouse Gas Emissions • Intergovernmental Panel on Climate Change Fifth Assessment Report (AR5) 100-year GWPs for CH4 (28)
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GHG Analysis Methodology 41 that estimate was applied to the U.S. Virgin Islands as well [Center for Climate Strategies (CCS)
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42 An Update on Public Transportation's Impacts on Greenhouse Gas Emissions Transportation Efficiency: Calculating Avoided Emissions from Transit Passenger Travel The net GHG benefits of transit as calculated for this project include the avoided GHG emissions of private automobile use by transit passengers, also called transportation efficiency. The NTD-reported passenger mile data were the basis for this analysis using the calculations described here: • Avoided CO2 – Passenger miles × mode shift factor (0.329)
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GHG Analysis Methodology 43 Applying the older mode shift data used in the APTA Recommended Practice to the 2018 NTD data results in only a small difference nationally (4%) from the analysis in this study, but individual agencies analyzing their GHGs should use a locally appropriate factor.
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44 An Update on Public Transportation's Impacts on Greenhouse Gas Emissions – Avoided community vehicle miles/miles per gallon (22.5 2018 FHWA on-road light-duty vehicles) = avoided gallons of fuel – Gallons of fuel use × kg CO2 per gallon = kg CO2 • Avoided CH4 and N2O – Avoided community vehicle miles × kg GHG per mile × GWP = kg GHG CO2e • Upstream GHGs (well-to-pump)
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From page 45... ...
GHG Analysis Methodology 45 Personal Vehicle Emissions The GHG emissions associated with avoided personal vehicle use in the community are calculated based on avoided VMT using the same method described in the Personal Vehicle Emissions subsection of the Transportation Efficiency: Calculating Avoided Emissions from Transit Passenger Travel section of this appendix. Previous Research on Land Use Efficiency The previously mentioned study of 2005 transit impacts found that transit led to emissions reductions of 37 MMT CO2 annually in the United States, including a land use multiplier -- transit's indirect impact on household VMT -- of approximately 2× (Bailey et al.
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From page 46... ...
46 An Update on Public Transportation's Impacts on Greenhouse Gas Emissions VMT saved in the community per transit passenger mile. This combines the direct VMT savings of transit passengers with the broader VMT savings due to transit's impacts on land use.
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