Development and Validation of a Vehicle Dynamics-Integrated Traffic Safety Simulation Environment for Enhanced Surrogate Safety Measures

A vehicle dynamics model (i.e., CarSim) was integrated with a microscopic traffic simulation model (i.e., VISSIM) for a surrogate safety assessment. This idea was initiated from the fact that the microscopic traffic simulation model generates various traffic situations and the vehicle dynamics model has an extensive capability of modeling the vehicle dynamics including pitch, yaw, and roll as well as generating realistic vehicle trajectories. In addition, a driver aggressiveness model, which was derived from the Next Generation Simulation (NGSIM) project lane change vehicle trajectories, was incorporated into the lane change vehicles in VISSIM. The resulting VISSIM vehicle trajectories were processed through CarSim to account for the vehicle dynamics and the traffic conflicts were identified through the Surrogate Safety Assessment Model (SSAM). The VISSIM-CarSim integrated simulation environment resulted in 9.5 % fewer traffic conflicts as compared with the VISSIM only approach. The results of the two conflict estimation approaches, that is, one from the proposed VISSIM-CarSim integrated approach and the other from the VISSIM only approach, were analyzed to estimate their correlation with the actual traffic crashes. These correlations were then used to assess and compare the effectiveness of these two approaches for assessing traffic safety. This analysis showed that the traffic conflicts obtained from the proposed approach exhibited a stronger correlation (i.e., 0.72 correlation coefficient) with traffic crashes than the existing approach did (i.e., 0.61 correlation coefficient). Traffic conflicts computed for both approaches showed statistically significant relationships with the actual traffic crashes. In addition, a cross-validation test on the confidence intervals of the correlation coefficients showed that the correlation coefficients have very tight confidence intervals (i.e., 0.02 for both cases). This indicated that while traditional traffic conflicts can be used as a traffic safety estimator, the newly developed vehicle dynamics model-integrated traffic safety simulation environment is a superior and valid alternative for assessing the surrogate safety.     «

A vehicle dynamics model (i.e., CarSim) was integrated with a microscopic traffic simulation model (i.e., VISSIM) for a surrogate safety assessment. This idea was initiated from the fact that the microscopic traffic simulation model generates various traffic situations and the vehicle dynamics model has an extensive capability of modeling the vehicle dynamics including pitch, yaw, and roll as well as generating realistic vehicle trajectories. In addition, a driver aggressiveness model, which wa...     »