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106 Glossary Biogenic Greenhouse Gas Greenhouse gas emissions resulting from fuels sourced from plant matter and part of the natural carbon cycle. Biogenic carbon dioxide, CO2(b), is often tracked separately from other greenhouse gas emissions. Bus Rubber-tired vehicle operating on roadways. For the purposes of this report, âbusâ also includes the NTD modes of âbus rapid transit,â âcommuter bus,â âpublico,â and âtrolleybus.â Carbon Dioxide Equivalent CO2e is the sum of greenhouse gases weighted by their relative 100-year climate impact using global warming potentials. Commuter Rail Train service that is typically region wide. Commuter rail in the 2018 NTD was fueled by biodiesel, diesel, or electricity. For the purposes of this report, the mode type âcommuter railâ also includes NTD modes âAlaska railroadâ and âhybrid rail.â Direct GHG Emissions The CO2, CH4, and N2O emissions that occurred at the vehicle when fuel was consumed. Electric Battery Bus A fully electric bus that stores electricity in a battery pack and uses it to power the vehicle. In this report, an electric battery bus is not a hybrid electric vehicle. Electric Propulsion Bus A bus propelled by electricity through an overhead wire or other continuous external source; also called a âtrolleybus.â Emissions Factor The greenhouse gas emissions associated with a unit of activityâ for example, carbon dioxide per gallon of gasoline. Ferry/Ferryboat Watercraft used as public transportation. Ferryboats in the 2018 NTD were fueled by biodiesel or diesel fuel. Global Warming Potential The energy absorbed by a greenhouse gas relative to carbon dioxide. This report uses 100-year GWPs of 28 for CH4 and 265 for N2O. Greenhouse Gas Gases creating the greenhouse effect, absorbing and emitting heat in the atmosphere. Heavy Rail An electric-powered train with high capacity. Indirect GHG Emissions The CO2, CH4, and N2O emissions that occurred at the power plant when electricity was produced or in the process of pro- ducing hydrogen.
Glossary 107Â Â Land Use Efficiency GHG Savings The GHG emissions saved by the broader impact of transit on VMT in the community, such as through shorter trips and fewer personal vehicle trips (also called indirect effect). Light Rail A lower-capacity train powered by electricity. For the purposes of this report, the mode type light rail also includes NTD modes âcable car,â âinclined plane,â âmonorail,â âautomated guideway,â and âstreetcar rail.â Mode Shift Factor The share of public transit passenger miles that would have otherwise been personal vehicle miles, such as through driving, carpooling, ridehailing, or taking a taxi. Occupancy The number of passengers per vehicle seat. Passenger Mile One mile ridden by a public transit passenger. Personal Vehicle Automobiles and light trucks; for the purpose of this report, includes ridehailing and taxi vehicles for hire; also called âprivate automobile.â Ridehailing A hired car for a single trip; also called âtransportation network companyâ; examples are Uber and Lyft. Transit Multiplier The ratio of the total VMT reduction associated with transit, including (1) the direct impacts of avoided personal vehicle travel by transit passengers and (2) the indirect effects of avoided travel in the communities with transit due to factors such as shorter trips and fewer personal vehicle trips, divided by the VMT reduction associated with transit use alone. Transit Vehicle Miles The full distance a transit vehicle travels, including revenue and non-revenue miles. Transportation Efficiency GHG Savings The GHG emissions saved by passengers riding transit rather than using automobiles (also called âdirect effectâ). Upstream Emissions The GHG emissions that occurred during fuel production and distribution; also called âwell-to-pumpâ emissions. Van Rubber-tired vehicles operating on roadways and having smaller seating capacity than buses. The NTD describes vans as seating 8 to 18 passengers. For the purposes of this report, the mode type âvanâ also includes NTD modes âdemand responseâ and âjitneyâ and may include smaller passenger vehicles.