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Reducing Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two: Final Report (2019)

Chapter: Appendix E: Description of Drive Cycles Used for Compliance

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Suggested Citation:"Appendix E: Description of Drive Cycles Used for Compliance." National Academies of Sciences, Engineering, and Medicine. 2019. Reducing Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/25542.
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Page 400
Suggested Citation:"Appendix E: Description of Drive Cycles Used for Compliance." National Academies of Sciences, Engineering, and Medicine. 2019. Reducing Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/25542.
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Page 401
Suggested Citation:"Appendix E: Description of Drive Cycles Used for Compliance." National Academies of Sciences, Engineering, and Medicine. 2019. Reducing Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/25542.
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Page 402
Suggested Citation:"Appendix E: Description of Drive Cycles Used for Compliance." National Academies of Sciences, Engineering, and Medicine. 2019. Reducing Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/25542.
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Page 403
Suggested Citation:"Appendix E: Description of Drive Cycles Used for Compliance." National Academies of Sciences, Engineering, and Medicine. 2019. Reducing Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/25542.
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Page 404
Suggested Citation:"Appendix E: Description of Drive Cycles Used for Compliance." National Academies of Sciences, Engineering, and Medicine. 2019. Reducing Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/25542.
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Page 405

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E Description of Drive Cycles Used for Compliance A total of 11 vehicle drive cycles were used in the study. Each cycle is described in this section. The Northeast States Center for a Clean Air Future (NESCCAF) cycle was developed to represent a typical line-haul type of operation. There are brief urban/suburban sections at the beginning and end of the cycle, to represent getting out to the highway. The main portion of the cycle consists of five cruise segments at speeds of 65 to 70 mph. The second cruise segment has an alternating +/-1 percent grade, and the third segment has an alternating +/-3 percent grade. The NESCCAF cycle is the only cycle that includes grades. Because tractor-trailer trucks cannot normally maintain cruise speed on a 3 precent grade, the cycle was given a feature that extended the drive time to force the vehicle to complete the required distance. Figure D1 shows the speed versus time trace, and Figure D2 shows the grade versus time trace. This cycle was only used for tractor-trailer trucks. FIGURE E-1 Speed versus time trace for the NESCCAF cycle. SOURCE: Reinhart (2015) Prepublication Copy – Subject to Further Editorial Correction E-1

FIGURE E-2 Grade versus time trace for the NESCCAF cycle. SOURCE: Reinhart (2015) Figure D3 shows the World Harmonized Vehicle Cycle (WHVC). This cycle is intended for medium- and heavy-duty trucks and includes urban, suburban, and highway segments. The cycle assumes that a road speed governor is used to limit speed to about 53 mph, which is required in Europe. The WHVC was used for all vehicles, to provide a way to compare results across different vehicle types. FIGURE E-3 World Harmonized Vehicle Cycle (WHVC). SOURCE: Reinhart (2015) Prepublication Copy – Subject to Further Editorial Correction E-2

The FTP-Highway cycle shown in Figure D4 has been used for many years to evaluate light-duty vehicle fuel economy. This cycle was developed in the time of the 55 mph speed limit, so speeds are low compared to typical modern highway driving, and accelerations are gentle. This cycle was only used for the pickup truck. FIGURE E-4 FTP-Highway drive cycle. SOURCE: Reinhart (2015) The FTP-City cycle shown in Figure E-5 has been used for many years to evaluate light-duty vehicle fuel economy. The cycle uses relatively gentle accelerations compared to what is found in typical city driving, and idle time is less than would be expected in typical city driving. This cycle was only used for the pickup truck. FIGURE E-5 FTP-City drive cycle. Prepublication Copy – Subject to Further Editorial Correction E-3

SOURCE: Reinhart (2015) The California Air Resources Board (CARB) urban cycle shown in Figure E-6 is used in the Greenhouse Gas Emissions Model (GEM) for medium- and heavy-duty vehicles. This cycle simulates urban driving for trucks. The CARB cycle was used for all vehicles simulated, except the pickup truck. FIGURE E-6 CARB urban truck driving cycle. SOURCE: Reinhart (2015) The US06 cycle shown in Figure E-7 is a more aggressive drive cycle for light-duty vehicles. It was introduced to help compensate for the overly optimistic fuel economy values generated by the older FTP city and highway cycles. This cycle was only used for the pickup truck. FIGURE E-7 US06 aggressive light-duty drive cycle. SOURCE: Reinhart (2015) Prepublication Copy – Subject to Further Editorial Correction E-4

The SC03 cycle shown in Figure E-8 was developed to evaluate the effect of air conditioner use in hot conditions on fuel economy. In this study, the air conditioner was run on all drive cycles, which is not the standard approach. This cycle was used only with the pickup truck. FIGURE E-8 SC03 air conditioner drive cycle. SOURCE: Reinhart (2015) The Parcel cycle shown in Figure E-9 was developed to model the drive cycle of a parcel delivery truck. About 50 percent of the drive cycle time is at idle. This causes fuel consumption at idle to be significant, especially with an automatic, where the torque converter load is significant. The Parcel cycle was only used for the T270 and F-650 medium trucks. FIGURE E-9 Parcel delivery drive cycle. SOURCE: Reinhart (2015) Prepublication Copy – Subject to Further Editorial Correction E-5

The Combined International Local and Commuter Cycle (CILCC) shown in Figure E-10 was developed to simulate urban driving. The general approach, with steady, very gentle accelerations, steady speed operation, and then gradual deceleration, is similar to the New European Driving Cycle. This cycle results in very light loads on the engine, and the cycle appears to be designed to favor hybrid systems. The braking sequences are gentle enough that almost all kinetic energy can be recovered by dynamic braking. The CILCC was only used for the T270 and F-650 medium trucks. FIGURE E-10 Combined International Local and Commuter Cycle (CILCC). SOURCE: Reinhart (2015) There are two remaining drive cycles that were used: the 55 mph and 65 mph cruise cycles. These cycles are strictly steady state, with no grades or other changes in load, so they effectively only operate the engine at one speed/load point. These two cycles are part of the GEM vehicle certification model. The 65 mph cruise was used for all vehicles in the study, while the 55 mph cycle was used for all vehicles except the pickup truck. Prepublication Copy – Subject to Further Editorial Correction E-6

Next: Appendix F: Summary of Committee's First Report: Reducing the Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two: First Report »
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Medium- and heavy-duty trucks, motor coaches, and transit buses - collectively, "medium- and heavy-duty vehicles", or MHDVs - are used in every sector of the economy. The fuel consumption and greenhouse gas emissions of MHDVs have become a focus of legislative and regulatory action in the past few years. This study is a follow-on to the National Research Council's 2010 report, Technologies and Approaches to Reducing the Fuel Consumption of Medium-and Heavy-Duty Vehicles. That report provided a series of findings and recommendations on the development of regulations for reducing fuel consumption of MHDVs.

On September 15, 2011, NHTSA and EPA finalized joint Phase I rules to establish a comprehensive Heavy-Duty National Program to reduce greenhouse gas emissions and fuel consumption for on-road medium- and heavy-duty vehicles. As NHTSA and EPA began working on a second round of standards, the National Academies issued another report, Reducing the Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two: First Report, providing recommendations for the Phase II standards. This third and final report focuses on a possible third phase of regulations to be promulgated by these agencies in the next decade.

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