Confidence limits for motorcycle speed from slide distance

In many motorcycle accidents, the motorcycle falls to the ground and slides to rest following impact or loss of control. The determination of the motorcycle speed just prior to 'fallover' is important for biomechanics research and for litigation. This paper presents a new model of motorcycle fall-over and slide, which accounts for the loss of horizontal momentum resulting from the initial motorcycle-to-ground impact and the subsequent slide to rest. The model includes cases involving motorcycle fall-over owing to loss of control as well as impact. The models represent both the mean and variation present in the available experimental data for dry roads very well and are used to develop confidence limits for accident reconstruction purposes, in cases where only the motorcycle slide distance along the ground is known. Previously proposed confidence limit criteria are applied to predicting motorcycle speed ranges from slide distance, and it is shown that the level of prediction uncertainty can be substantially reduced in cases where additional information specific to the vehicle and road configurations is available.