Impact throw model for vehicle-pedestrian collision reconstruction

Abstract

A planar model for the mechanics of a vehicle-pedestrian collision is presented, analysed and compared with experimental data. It takes into account the significant physical parameters of wrap and forward projection collisions and is suitable for solution using mathematics software or spreadsheets. Parameters related to the pedestrian and taken into account include horizontal distance travelled between primary and secondary impacts with the vehicle, launch angle, centre-of-gravity height at launch, the relative forward speed of the pedestrian to the car at launch, distance from launch to a ground impact, distance from ground impact to rest and pedestrian-ground drag factor. Vehicle and roadway parameters include post-impact, constant velocity vehicle travel distance, continued vehicle travel distance to rest with uniform deceleration and relative distance between rest positions of vehicle and pedestrian. The model is presented in two forms. The first relates the throw distance to the initial vehicle speed. The second, intended for reconstruction, relates the vehicle speed to the pedestrian throw distance. The first form is used as means of comparison of the model with selected sets of experimental data taken from the current literature, including a variational study using Monte Carlo simulation. The second (reconstruction) form is derived analytically not empirically and the parameters have physical interpretations. In order to obtain parameter values, direct calculation or the method of least squares can be used. A comparison of the reconstruction model with results of other reconstruction models is presented.