Perspective on impact biomechanics from traffic accident analysis

This paper begins with a brief review of the development of crash investigation techniques from the 1950s to the present day. Early work at Cornell University in the United States led to studies in Australia, Sweden and the United Kingdom and a general recognition of the fundamental importance of a detailed knowledge of the nature and circumstances of actual trauma to traffic accident victims. Today a number of countries have on-going structured sample date collection programmes which provide an important means of assessing the effectiveness of biomechanical advances which are implemented through changing car design and regulations. Notably, the NASS/FARS programmes in the United States, by being freely available electronically, have become a valuable source to other countries. Such research illustrates an important yet still poorly understood aspect of impact biomechanics; that of variation within the population at risk. Examples are given of this issue in terms of head, neck, thoracic, leg and abdominal injury studies to show that a factor of three exists between the weakest and strongest elements of the normal population exposed to impact injury. Age and gender effects are discussed. The optimisation of protection recognising the two distributions of crash severity and impact tolerance variations leads to the conclusion that focusing on very severe collisions does not result in good overall protection. The links with experimental biomechanics are illustrated and the paper concludes with proposals for new research directions with increasingly detailed instrumentation of vehicles and more realistic modelling of the human frame.