Uncertainty Analysis of the Preimpact Phase of a Pedestrian Collision

The problem of uncertainty is particularly important in the analysis of accidents involving pedestrians because even slight but simultaneous modifications of many data can result in shifting the responsibility line.

Calculations include a number of irreproducible parameters whose numerical values are either selected from literature (e.g. reaction time, lag time, friction coefficient) or on the basis of verbal description (e.g.: “…when he was still running along the sidewalk, it was obvious he was going to rush into the roadway”, “the car wasn't braking too hard”). Additional difficulty is caused by performing mathematical analyses of different versions given by the witnesses (e.g.: “he was walking slowly”, “he was walking at a fast pace”), which together with other uncertain data lead to a large number of additional “subversions”. In the paper an analysis of the sensitivity of function describing the kinematics of a pedestrian accident has been made. The essential parameters have been pointed out and, using a real example, uncertainty calculations have been performed employing graphical, analytical and Monte Carlo Simulation methods. The boundary values have been highlighted, which facilitates the interpretation of a large number of “sub-versions”, and consequently, taking the right decision by the court.