Assessing risk factors associated with urban transit bus involved accident severity: a case study of a Middle East country

摘要

While buses are a safe form of transport in developed countries, developing countries like Iran face significant safety concerns regarding buses. Nevertheless, few studies have examined the factors associated with the number and severity of bus crashes. The present study investigates the underlying risk factors associated with the severity of urban transit bus accidents in Mashhad, Iran, by estimating a binary logit model. Data for the analysis are retrieved from Mashhad Bus Company Safety Office between the years 2014 and 2016. Accident severity is divided into PDO (Property Damage Only) and injury or fatal categories, and the effect of several risk factors on the probability of bus accidents with higher severity is examined. Results from this study indicate that bus accident severity is positively associated with the speed limit and the presence of vulnerable road users as the other involved party. Furthermore, bus accident occurrence at bus stops and roundabouts decreases the probability of injury or fatality in comparison to the roadway segments. Focusing on the accident type, in comparison to single-vehicle accidents, collisions with other vehicles decrease the probability of injury or fatal accidents for buses. Among different types of collisions, angle and sideswipes are the most and least probable types of crashes to result in injury or fatality, respectively. Model results show that time-related variables, median presence, bus age, and bus model are not significantly associated with the bus accident severity. The results of this study provide a relatively comprehensive picture of bus safety in Mashhad.