Technical Document and User Guide for the Multi-Modal Passenger Simulation Model for Comparing Passenger Rail Energy Consumption with Competing Modes (2015)

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Appendix B Terms, Abbreviations and Equation Variables

B-1 B.1 Terms Balance speed Speed at which a train’s tractive effort equals the sum of its up-grade and resistive force. Breakeven grade Speed at which a train’s downgrade force equals the resistive force. Cruise segment Portion of a trip taken at constant ‘cruise’ speed. Cruise speed Speed maintained on a long haul segment of a trip. Consist The locomotives and cars comprising a train. Delay Unscheduled events that add to a trips minimum travel time. Dg-set Diesel generator set used to generate hotel power. Dynamic braking Slowing a train by using traction motors to convert kinetic energy into electricity which is then dissipated as heat in resistance grids. Hotel power Electrical power provided for use by passenger compartments. Regeneration Conversion of kinetic energy into electrical energy during braking (usually back into the electricity grid or onboard storage rather than simply dissipated as heat as in dynamic braking). Schedule slack Time allowance built into a schedule in excess of the minimum run time to accommodate unscheduled delays. Steps Segments of track processed in one calculation row of the rail simulation sheet (segments are normally based on lengths of constant posted speed). Tractive effort The propulsive force generated at a powered axle’s wheel (mostly by electric traction motors). Wayside At the side of the tracks.

B-2 B.2 Abbreviations ABA – American Bus Association AC – Aircraft AREMA – American Railway Engineering and Maintenance-of-Way Association A T R I – American Transportation Research Institute Bsfc – Brake specific fuel consumption BTS – Bureau of Transportation Statistics CN – Canadian National CVT – Continuously variable transmission CY – Calendar year D – Destination DEM – Digital elevation models DMU – Diesel multiple unit DOT – Department of Transportation EMU – Electric multiple unit FE – Fuel economy FW – Freeway GC – Great circle GHG – Greenhouse gas GHGeq – Greenhouse gas equivalent HEP – Head-end power HSR – High speed rail ICAO – International Civil Aviation Organisation IPCC – Intergovernmental Panel on Climate Change IR – Inherent resistance LDT – Light duty truck LDV – Light duty vehicle LOS – Level of service (a highway capacity metric) LTO – Landing and takeoff MBTA – Massachusetts Bay Transportation Authority MY – Model year NBJ – Narrow body jet NCDC – National Climate Data Center NTD – National Transit Database

B-3 O – Origin OD – Origin-destination pGCkm – passenger great circle kilometer PL – Payload RDC – Rail diesel car RF – Radiative forcing RJ – Regional jet sGCkm – seat great circle kilometer skm – seat kilometer SRJ – Small regional jet TE – Tractive effort TP – Turboprop TSO – Temporary slow order UDDS – Urban Dynamometer Driving Schedule VHSR – Very high speed rail Vkm – vehicle kilometer WBJ – Wide body jet WGI – Working Group I

B-4 B.3 Equation Variables a Coefficient A Acceleration A Frontal area b Coefficient Cd Aerodynamic drag coefficient Cra Coefficient of rolling resistance & hysteresis Crai Tractive effort envelope coefficient Crb Coefficient of dynamic resistance Crbi Tractive effort envelope coefficient Crc Coefficient of aerodynamic resistance Crci Tractive effort envelope coefficient Crdi Tractive effort envelope coefficient dt Time step Fh Hotel power diesel generator set fuel consumption rate g Gravitational acceleration Gbe Breakeven down grade Gmx Maximum grade that can be climbed at cruise speed IR Inherent Resistance Kr Mass-equivalent rotational inertia of an axle M Mass Na Number of axles P Power R Ratio of cold-start/hot start fuel increment SF Scale factor for aerodynamic drag t Time T Temperature TE Tractive effort TEi Tractive effort Ta Ambient temperature V Speed ρ Density of air