Comparative analysis of methods to estimate the tire/road friction coefficient applied to traffic accident reconstruction

The measure of the friction factor in the location of the event is very important to get accurate inputs to model the accident, as the friction factor depends on environmental conditions and the dynamics of the event. In some low-middle income countries, accident reconstruction experts, usually don't have the feasibility to acquire expensive equipment as high precision accelerometers; therefore, it is important to identify a low-cost method that provides data quality comparable with high precision equipment. This study presents a comparison of three methods: VC4000PC accelerometer, sensor kinetics mobile app and video analysis by tracker (free software). The methods have been compared experimentally for emergency braking with blocked wheel, as well as using ABS. Data from the three methods were recorded simultaneously. Data analysis was made applying inferential statistics. The results indicate that the data collected with the smartphone app ensure good accuracy and does not provide significant variance in comparison with the accelerometer. On the other hand, the data obtained by video analysis shows a good linear relationship with the accelerometer; however, it shows some statistical evidence of differences related to precision and variances in comparison with accelerometer device. The confidence interval, absolute error, and other estimators have been obtained for the smartphone method, to promote the optimal using by the experts to get parameters on site and apply to a traffic accident reconstruction.