The PURPOSE of the paper is to develop the procedure for determining optimal parameters of “driver - vehicle - road - environment” system elements under which system maximum reliability is achieved, i.e. to create a model that allows to identify potentially dangerous elements of the system. The formation of optimal parameters of the “driver - vehicle - road - environment” system is reduced to the task of determining the system parameters under which the probability of accident occurrence is minimal. METHODS. The task set is solved by the method of hierarchy analysis based on the decision-making theory developed by T. Saati and taking into account the mutual influence of parameters. RESULTS. The authors propose a mathematical model on the basis of which the probabilities of a road accident have been calculated on two different sections of the federal road R255 at daylight under similar parameters of the “driver - vehicle - road - environment” system: driver, vehicle and environment. Practical application of the introduced procedure will lower the probability of road accidents by reducing the accident rate of priority parameters of the “driver-car-road-environment” system. CONCLUSIONS. The article provides a mathematical model that allows to determine such parameters of the “driver - vehicle - road - environment” system under which the probability of an accident is minimal. The accident rate which takes its values depending on the actual values of a particular parameter and the priority vector that defines parameter importance has been used to determine the probability of an accident. Reduction in the value of the priority parameter accident rate reduces the accident probability. A correlation model describing the dependence of accident probability on the driver, vehicle condition, roadway condition, traffic intensity including the speed of the vehicle and distance between the vehicles for different road sections, as well as road illumination and weather conditions has been obtained.