An accurate reconstruction of events immediately leading up to an accident is desirable for the police, insurance purposes and for research into road safety. An understanding of vehicle impact dynamics helps in these investigations because it provides a link between the various pieces of evidence which may be available: the verbal evidence, the position of damage to vehicles and to fixed objects, the extent of damage to vehicles, tyre marks on the road and the condition of the surface, movements of vehicles after impact, the distribution of debris. Such evidence may enable the initial paths and speeds of travel to be estimated. The relative masses and the initial point of contact also determine how the vehicles rebound after impact. The relative stiffnesses of the parts of the vehicle in contact play an important part in the situation, though their evidence can be misleading. Some examples of accident situations demonstrate that the estimation of velocity changes at impact is a relatively complicated task, and the results vary greatly with the assumptions made. It is concluded that though theoretical calculations may help in the understanding of a situation, their results must be used with discretion. (Author/publisher)
Abstract