The physics of automobile collisions and road traffic safety

Abstract

A survey is given of the interdependent physical variables and principles relevant to the motion of a road vehicle in a traffic situation and its application to analyse and prevent actual collisions. As introduction recent RSA collision statistics and research results on contributing factors and types of collisions which occur, are presented. Then speed as cause is investigated with a discussion of the relative velocity between vehicles; stopping ability and safe following distances; the decision to stop or not at a changing traffic light; as well as estimations of the speed before collisions from wheel skidding marks and projectile flips and vaults. Thirdly vehicle stability is discussed with applications of weight displacement during sudden accelerations; explanations for skidding out of and turning over on a road bend; as well as load displacement.