Investigation of probability of road accidents risk in different climatic conditions in suburban axes of Semnan province

Today, the severity and number of road accidents caused by climatic factors has increased in the suburban roads of Semnan province; Therefore, this study, due to the importance of the subject and with the aim of investigating the probability of road accidents risk in different climatic conditions, was conducted for the main suburban axes of Semnan province.

In order to obtain the probability of road accidents risk in different climatic conditions by descriptive-analytical method, first was paid to collect and process data of climatic elements affecting road accidents in a period of 15 years from 5 synoptic stations, 14 main axes and traffic data in 2016 to 2018; Then, data were analyzed based on Palm's probabilistic concept and stochastic process theory.

The highest palm probability and relative accident risk for the type and intensity of rainfall were calculated to be 0.845 for no rainfall and 2.18 for snowy days, respectively. The relative accident risks for rainfall type, rainfall intensity and weather conditions on Highway 44 are twice as high as for other types of roads.

The relative risk of accidents increases with unfavorable weather conditions at a severe rate on the roads; Roads and passes in the cold semi-arid regions of the province, such as Ahovan Pass, Bashm, Khosh Yilagh, Foolad Mahaleh in winter, have snow and icy conditions; While in the desert roads of the province in summer, the climatic element of maximum temperature is the most effective factor in accidents.