Prediction of the Probability of Occurrence of Overturn Crashes in Suburban Freeway Based on the Logistic Regression Function (Case Study: Zanjan-Qazvin and Zanjan-Tabriz Freeways)

Overturn crashes are one of the most important road hazards. Due to the high severity and significant contribution of these types of accidents, it has created a set of preventive measures to reduce the consequences of these types of accidents. Therefore, the present study aims to provide a statistical model using two-dimensional logistic regression, in order to identify the variables that affect the probability of occurrence of overturned crashes in suburban roads. For this research, information from Form 114, traffic volumetric information and meteorological information in the years 92, 93 and 94 were used for Zanjan-Qazvin and Zanjan-Tabriz freeways. The results of this study showed that the probability model of free overturn crashes of Zanjan-Tabriz freeway was achieved by three independent variables of gender, driver's occupation and geometric status with an accuracy of 81%. While the probability occurrence model, the overturn crashes in Zanjan-Qazvin freeway were only achieved using two independent variables of driver occupation and load type with a percentage accuracy of 71%. Given to Zanjan-Tabriz model (the superior model), it can be concluded as a general result that overturned accidents are more dependent on human factors.