A new method for determining an overall unsignalized risk index based on traffic conflict indicators

Traffic accidents on Iran’s road networks cause thousands of deaths and injuries every year, and cost the country’s economy billions of dollars. An intersection is a planned point of conflict in the roadway system. With different crossing and entering movements by both drivers and pedestrians, an intersection is one of the most complex traffic situations that motorists encounter. In small areas such as intersections, especially in resolution of maneuvers, identification of hazardous situations is impossible by using accident data for reasons such as the low occurrence of accidents and not specifying the exact location of the accident event. Therefore, in this study has been used the traffic conflict which were obtained from video analyzing. By using Time-to-collision (TTC) indicator and traffic volume, risk zone have been identified. As a case study, four leg unsignalized intersection located at the crossroad of Vessaleshirazi-Bozorgmehr in Tehran was chosen. The evaluation results showed that zone 3 is dangerous zone. The risk of zone 3 was 402.95 that was about 6.8 times the average risk of intersection. This conflict was the main reason for the increasing of the intersection risk.