Influence of Vehicle Inertia Tensor and Center of Gravity Location on Road Accident Reconstruction

The paper is divided into two parts and deals with the accurate reconstruction of automobile accidents. In the first part of the paper, a mathematical procedure is presented to perform an accident reconstruction with the data that are usually collected by operators after the impact. Some real cases have been considered to validate the procedure. The method has allowed to identify the final location of the impacting vehicles and their initial velocity with reasonable accuracy. The second part of the paper refers to a sensitivity analysis for quantifying the effects on a proper accident reconstruction of the uncertainties of the location of the centre of gravity and of the moment of inertia around the vertical axis of the (two) crashed vehicles. The final aim of such a theoretical investigation is assessing and prescribing the measurement accuracy of the centre of gravity location and of the inertia tensor components of crashed vehicles. An existing test rig for measuring the c.g. location and the inertia tensor of crashed vehicles (pre- and post-impact), meeting the accuracy determined on the basis of the theoretical study, is presented. Contrary with respect to what it seems the current opinion, from our theoretical analysis, it appears that an accurate accident reconstruction needs accurate measurements of both the centre of gravity location and the inertia tensor of crashed automobiles.