Development of Traffic Safety Evaluation Method based on Simulated Conflicts at Signalized Intersections

In this study simulated conflicts were used to pre-evaluate the safety performance of signalized intersections. A signalized intersection was selected and the traffic operation was simulated in VISSIM simulation system according to the field traffic information. Then the output vehicle trajectory file was analyzed by Surrogate Safety Assessment Model (SSAM) to identify simulated conflicts. Simulated conflicts generated by the VISSIM simulation and identified by SSAM were compared to the traffic conflicts measured in the field, and a two-stage calibration procedure was carried out to improve the goodness-of–fit between these two conflicts. After calibration and validation, the remedial measure for this intersection, reducing the speed limit from 60 km/h to 50 km/h, were applied in the VISSIM simulation model. Comparing the simulated conflicts under different speed limits, it was found that the safety performance of this intersection was improved after reducing the speed limit.