earticle

영어

This study has implemented before and after analysis for traffic accident rate on the 38 IC sections of 9 expressways during three years before construction, construction periods, and three years after construction respectively. The number of accident and fatalities had slightly increased during construction period compared to before construction and then had decreased after the construction was completed. In the case of the number of injured, it had continuously decreased through three periods. Especially, it had sharply dropped after the construction was completed. According to the paired t-test, the average of accident between the construction period and the period after construction is different. The average of fatalities is different between before and after the construction, and also during and after the construction. The average of injured is totally different at every three periods. The number of accident, injured, and fatalities had largely decreased by 41, 32, and 62 percent respectively when is compared to before and after expressway widening project. It could support the hypothesis that the widening project could result in lower accident rate while increasing road capacity. This study has a value as a comprehensive before and after study for traffic accident rate on the widening project section of expressway, which is hard to find out similar studies in the past due to data limitation. The result of this study could use as a basic unit (per unit) of traffic accident rate when the preliminary feasibility study is implemented for the widening project. The current method of estimating traffic accident cost savings has a significant limitation in reflection of impact on safety improvement because it is calculated based on vehicle-km. Therefore, traffic congestion level needs to be considered in the process of preliminary feasibility study for the highway project.