Established methods in accident investigation and reconstruction rely on the identification and interpretation of physical evident from the scene and from the vehicles, using basic physical laws. Such techniques require investigators to make some assumptions and to simplify their analyses such that vehicle movements become treated in an idealised manner, and they therefore do not provide investigators with fully effective procedures for addressing the non-standard situations which drivers encounter. One factors which is often put forward as a contributory or even the main cause of an accident is incorrect tyre pressure, when in reality there is an absence of independent knowledge of its effect, particularly for modern tyre designs that may be temporarily driven on after partial or total loss of pressure (commonly referred to as run flats). This experimental programme has focused on investigating the effects of modern tyre technology on the tyre/pavement friction (low Profile and run flats) and on vehicle braking performance and handling characteristics (run Flat). The components of the experimental programme combine to build up an understanding of the effect of inflation pressure for a rnage of modern tyre types and operating conditions, so providing the accident investigator with a source of data on the performance of modern tyres. Some statistically significant difference between under-inflated tyres and those inflated to recommended pressure were identified. However, whilst under-inflation may have profound effects on the nature of vehicle control (and this bears strongly on accident probability), its effect on the reliability of conceptual accident reconstruction given physical data (tyre marks on the road etc.) is small. The most significant differences for accident reconstruction purposes were found when a run-flat tyre is completely deflated, this having resulted in a loss of vehicle control during one experiment. (A)
Abstract