| Abstract | There is a need for a better consideration between the relationship of the injury severity of accident and the factors which are responsible for causing accidents, to develop effective countermeasure to reduce the rate of accidents as well as the severity of injury during an accident. As intersection is a crucial part of any roadway network, which is also one of the most accident prone area, due to the availability of several conflict points. There is a need to understand the factors which affects the accidental rate and causes higher injury severity at an intersection. There have been very few studies in the past to better understand the contributing factors of intersection accidents. In an attempt to identify the high risk factors causing severe accidents at intersection, various factors have been considered which include: general characteristics, vehicle characteristics, roadway characteristics, environmental conditions, type of accidents occurring, probable cause of accident, collision pattern, and the traffic controls have been investigated in this study. We have also included different scenarios and condition like intersection accidents at night time, intersection accidents involving motorcycles only, and intersection accidents involving big trucks only, as to discover the factors responsible for the occurrence of accident and causing high severity to the occupants. Finally a comparison study was also done on the low/no accident intersection and high accident intersections, as to find out the difference in features and factors which makes an intersection a high risk location. To establish the relationship between the injury severity and the risk factors, an ordered probit model was developed which is considered as a suitable model due to the ordinal nature of the injury severity level. The reported accidents as collected by the Department of Highway of Thailand from 2007 to 2009 were used to calibrate the model. Hence from a total of 47pre-selected factors, the significant factors in each of the model were identified and thus interpreted. It was found that the most severe accident occurs between a motorcycle and big truck, while passenger cars are relatively safe. Increase in the number of lane decreases the severity of injury. Accidents occurring at night time are more severe than that of day time. Collision patterns such as turning side on, turning rear end and rear end collisions have a higher impact on severity. There seems to be an increase in accident severity on intersection where there are traffic signal and warning flash lights available as well. |