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Furthermore, 183car-to-pedestrian cases, with detailed information regarding accident vehicles, pedestrians and environment, were reconstructed using PC-Crash. A hypothetical autonomous braking system would activate when the pedestrian successfully detected by the sensing system and then new impact speeds will be calculated.

The software packages included in the studies presented in this paper are HVE (SIMON and EDSMAC4), PC-Crash and VCRware. This paper will present the results of the study, conducted using DOE, involving these models.

Knowledge about vehicle rolling resistance is required to calculate speed loss of accident vehicles during portions of their pre-impact and post-impact trajectory when they are not braking or sliding directly sideways. The accuracy of assumed rolling resistance values is most important in accidents with long post-impact roll out distances. Very little hard data are currently available1 and the accident reconstructionist must usually make estimates of drivetrain losses and normal and damaged tire rolling resistance to determine overall vehicle rolling resistance. In the first part of this study, the rolling resistances of various vehicles with different drive configurations are determined, based on accurate measurements made with a 5th wheel. In the second part, sensitivity analyses are done with PC-Crash2, a computer simulation program, to determine what effect the error in assumed rolling resistance has on speed calculations for various types of post-impact trajectories.

Development of crash avoidance systems and active safety systems must not be only based on experimental knowledge. The goal is to provide an efficient answer to still unsolved severe real-world car crashes which occur despite enhanced passive safety devices. This requires to know precisely the pre-crash conditions during about 3 to 10 seconds before impact. The paper describes the multidisciplinary systemic approach leading to the comprehensive methodology used in accident reconstruction in order to determine the best scenario, and to assess initial car speeds, paths and events in the different phases of the accident. This has already been carried out for about 400 car crashes with car occupant injuries (including 6% fatal and 10% severely injured). The necessity of collecting data on the spot of the crash scene is highlighted. Three well-trained investigators are involved.