Aim.Derailments of rolling stock units (cars, locomotive units) of freight trains cause damage to roadbed and rolling stock, as well as possible loss of transported cargo. Of special interest are cases when derailed rolling stock units intrude into the operational space ofan adjacent track. This, for instance, happened in the case of the Moscow – Chișinșu train at the Bekasovo I – Nara line on May 20, 2014, when as a result of the derailment of freight cars with subsequent intrusion into the operational space of an adjacent track 6 people were killed as the result of collision with an opposing train. In some cases intruding units may collide with an opposing freight train, which may cause the death of that train’s crew and derailment of its cars, which in case of transportation of hazardous loads (e.g. oil and gasoline) may have catastrophic consequences. Intrusion into the operational space ofan adjacent track also interrupts the traffic in both directions. In this context, evaluating the probability of derailed cars intruding into the operational space of an adjacent track is extremely important in order to maintain the tolerable level of risk in railway transportation, while the aim of this paper is to construct functional dependences between the probability of derailed cars intruding into the operational space of an adjacent track and various factors.Methods. Probability theory and mathematical statistics methods were used: maximum likelihood method, logistic regression, probit regression, Cauchy regression.Results.For each of the groups of incidents: derailments due to faulty cars/locomotive units, derailments due to faulty track, using the classic binary choice model an estimation was constructed of the probability of at least one derailed freight car intruding into the operational space of an adjacent track. This estimation turned out to be dependent upon the train loading and number of derailed units. As the number of derailed units is a priori (before the derailment) unknown, it was suggested to construct the probability of intrusion by at least one derailed freight car into the operational space of an adjacent track using a parametric model of dependence between the average number of derailed units and various traffic factors. The resulting dependences were compared. A numerical example was examined.Conclusions.There is a significant direct correlation between the random values that characterize intrusion by at least one unit into the operational space of an adjacent track and the number of derailed freight train units. A direct dependence between the train loading and intrusion by derailed units into an adjacent track was established. In case of derailment due to faulty track, for loaded trains the probability of at least one derailed unit intruding into the operational space of an adjacent track is extremely high.
