Advanced mathematical and static methods of processing of the results of experimental studies, comparison of the obtained data with the works of authors investigating traffic safety, analysis, reconstruction and investigation of road traffic accidents, as well as expert analysis helped to identify the most relevant parameters of the vehicle condition and the road environment necessary for automobile technical expert evaluation (e.g. the friction coefficient, vehicle braking performance under different loads on all categories of roads with different types of road surface, roughness, wheel tracking, hydraulic roughness) and to obtain their actual values that are important for expert studies; and that was proved by experiments. The developed method of reconstruction and investigation of accidents implies calculation of state parameters of the vehicle and the road environment on the basis of the type of the investigated accident and geometric characteristics of the accident place.