Jakub Zębala

The article presents the results of a survey that involved determining the energy equivalent speed (EES) from experience, i.e. based solely on the photographic documentation of damaged vehicles after a collision. The aim of the study was to assess the usefulness of this method in the reconstruction of road accidents. A statistical analysis of the obtained results and a comparison between the survey results are presented in the article, i.e. the values indicated from experience and the EES values  calculated based on simulations conducted in the PC-Crash program, called ‘true values’in the article. The analysis of the obtained results shows that the EES estimation using this method can at most be an auxiliary tool in the reconstruction of road accidents, as it only allows for a very rough, preliminary determination of the EES before the application of a more accurate method of determining the permanent energy of vehicle deformation.

The possibility of modelling in the PC-Crash program of the motion on curved trajectory of a car whose rear wheel tire got unsealed, which resulted in the pressure drop to the atmospheric pressure, which was followed by the tire bead slipping off the rim, is analysed. The authors, using the results of the road tests they performed, reconstructed in the PC-Crash program the actual movement of the car. Next, they performed a number of simulations applying a bilinear model of a tire of default and modified characteristics as well as a TMeasy model. The effect of the change of wheel-to-road surface friction coefficient was also analysed. To compare the simulation results, the function of quality was employed whose value is the measure of the difference between the vehicle position and orientation obtained in simulation and the real ones. The most favourable results were reached when the TMeasy tire model was applied and the friction coefficient of the deflated tire on the distance between the point of the tire slipping off the rim and stopping was reduced.