Rollout Deceleration of Modern Passenger Vehicles 2012-01-0616

Vehicle post-impact travel distances are often available to the accident reconstructionist. Energy dissipated after impact can be significant, and it is often necessary to account for this energy. The deceleration and energy dissipation experienced by a vehicle after a collision is dependent on many variables including tire rolling resistance, engine and drive-train resistance and aerodynamic drag. New technologies that significantly modify the traditional drive train, low rolling resistance tires, and new aerodynamic body designs affect vehicle deceleration, but associated data is not widely available. Roll-out tests were performed in which speed, acceleration and position measurements were made. Vehicles tested were equipped with hybrid (gasoline-electric) and standard engines, CVT (continuously variable transmission), manual and automatic transmissions, and two wheel and four-wheel drive. Results are presented to characterize the effect of vehicle speed, gear, and ignition status (engine on or off). The different measurement methodologies employed are compared for accuracy, repeatability and ease of use. A review of published vehicle decelerations is presented and compared to the data collected in the current series of tests. The applicability of this new deceleration data to a range of vehicles similar to those tested is discussed.