Developing Real-World Drive Cycles for Heavy-Duty Freight Vehicles using On-Board Diagnostics Data

Driving cycles or drive cycles are plots of speed versus time used in vehicle testing to estimate fuel consumption and emissions. They are representative of a typical driving pattern of a vehicle type on a route (terrain). For developing drive cycles, the speed data of a vehicle are collected by the car chase method or using on-board devices (such as global positioning system devices); on-board devices provide more accurate speed data at second-by-second intervals than the car chase method. We used on-board diagnostic (OBD) devices to capture accurate speed–time profiles. About 0.4–0.5 million speed records from two heavy-duty freight vehicles (42 and 48 metric ton trucks) were obtained during their regular real-world operations for over a month on intercity routes in Karnataka, India. A modified random selection approach to sequence microtrips was used to synthesize drive cycles using OBD data. The developed drive cycles for the 42t and 48t trucks had a mean relative error of 8.34% and 9.63%, respectively, within the acceptable limit of 10%. Comparison of the developed drive cycles with the standard Indian and international drive cycles for heavy-duty vehicles showed significant differences in terms of average and maximum speed and duration. Of note, the study was limited to two trucks owing to data collection constraints, such as low on-road population of trucks with OBD-II ports in India and unwillingness of truck operators to allow plugging-in of devices for data collection. Thus, there is a need for similar studies with extensive data collection from multiple vehicles to draw broader conclusions.