Investigation the influence factors to severity tunnels accidents by Analytic Hierarchy Process (AHP)

Road accidents are one causes death in the worldwide. Tunnels are segments of road network which have fewer number of roads crashes than open road’s segment this is due to the lower tunnels’ length then the length of open segments roads. But severity of crashes are high in tunnels, therefore investigation influence factors to severity these types roads accidents are so important for traffic engineers. In this study, the main influence factors to severity tunnels accidents (STA) were investigated by using analytic hierarchy process (AHP) method and data collection with questionnaire from answer of safety experts. Seven main criteria were considered that included characteristic of drivers, environmental of tunnels (including: geometric design of tunnels, lighting and lining), conditional of weather, types of crashes, traffic flow, vehicles and time of occurrence. 16 experts’ answer were collected but according to value of consistency ratio (CI≤10%), only 10 of answers were acceptable. Result showed, type of crashes was important main criteria to STA and front-on crashes have high severity tunnels accidents. ADT, truck, width of lane, using drug and alcohol, time occurrence (6:00-18:00) and rainy weather were the most influence factors sub-criteria to STA. In this research, lengths of tunnels were divided three zones (entrance zone, middle zone and output zone). The results indicated that entrance zone have higher severity than others zone by experts’ answers.