Investigating the Contribution of Factors Influencing Accidents Severity on Intercity Roads Using the sequential logit model

The low level of road safety in the country and high crash statistics relative to the global average are nowadays a challenge for managers and decision makers in the field of transport and traffic. The accidents in addition to the many financial losses it causes, also result in many casualties and injuries. Therefore, researchers have focused much attention on analyzing the causes and severity of accidents to help provide appropriate solutions to reduce these damages.  the main objective of this study is to investigate the cause of accidents and determine the contribution of different parameters to the occurrence of an accident.

In this research, statistical modeling and determining the contribution of different factors in the occurrence of accidents were investigated using 2433 real accident data. Also, in this study, a sequential logit model is presented to predict the severity of accidents and determine the effect of each parameter. The results of the proposed modeling are also compared with current models such as neural networks.

Discussion of the results shows that the sequential logit model is more efficient than the neural network model. In addition, the presence of pedestrians has the greatest additive effect on the severity of accidents, and the right-lateral accidents has the greatest decreasing effect among the effective parameters. On the other hand, the distance from the origin and the accident in the early hours of the morning have the least additive effect and andthe least reducing effect on the intensity of accidents, respectively. After pedestrians, the presence of heavy vehicles at night has been the highest contributor to the increase in the accident severity. Suggestions: In future studies the effect of parametric factors such as the driver's familiarity with the route is investigated to predict the severity of accidents. Location-time analysis can be a great help in advancing researches in the context of the severity of accidents. From a practical point of view, it is also suggested that the education of drivers of public transport concerning the parameters affecting the increase in the severity of an accident be included in the agenda by the Road and Transportation Organization.