Safety Assessment of Signalized Intersection Using SSAM : A Case of Actuated Signal Control

The surrogate safety assessment model which was developed based on the conflict theory by FHWA in the US is software to analyze traffic conflicts using the individual vehicle trajectory data from a microscopic traffic simulation model. This study aims at assessing the safety of different signal control strategies, including pre-time and actuated signal control, using the SSAM. To this end, this study effort has developed a microscopic traffic simulation model using VISSIM through a field study, and then produced the surrogate measures, including TTC, PET, DR, MaxS and DeltaS, and the numbers of conflicts, including rear-end, right angle and lane-changing conflicts. The assessment results indicated that the actuated signal control may produce more conflicts in terms of rear-end conflicts. The use of SSAM in the safety assessments for diverse traffic alternatives in a safe and fast way may contribute to the improvement of safety in the roadway transportation.