Can Surrogate Safety Assessment Model Replace the Field Measurements of Traffic Conflicts?

The research presented in this paper studied the relationship between simulated traffic conflicts using the surrogate safety assessment model (SSAM) approach, and those measured in the field using traditional traffic conflicts techniques. Both traffic and conflict data were collected at 6 yield-controlled freeway ramp terminals in Nanjing. A series of linear regression models were developed to relate simulated traffic to real world traffic conflict. It was found that the relationships between simulated conflict and both total and severe conflict situations observed in the real world were in fact statistically significant, and also that the distribution of conflict types was reasonably similar. However when the conflict traffic volume was low, the relationship was not as significant. The research team also found that the linear regression model, based on conflicting traffic volumes, explained a higher percentage of variations in both total and severe conflicts observed in real world.