Development and Validation of a Vehicle Dynamics Integrated Traffic Simulation Environment Assessing Surrogate Safety

Abstract

A vehicle dynamics model was integrated with a microscopic traffic simulation model for a surrogate safety assessment. The research reported in this paper was initiated from the idea that existing microscopic traffic simulation models could be complemented with a vehicle dynamics model having an enhanced capability of realizing the vehicle dynamics including pitch, yaw, and roll and generating realistic vehicle trajectories. In addition, a driver aggressiveness model derived from a lane change vehicle trajectories model was incorporated into the lane change vehicles in the microscopic traffic simulation model. The resulting microscopic traffic simulation model vehicle trajectories were processed through the vehicle dynamics model to account for the vehicle dynamics and the traffic conflicts were identified through the surrogate safety assessment model. The integrated microscopic traffic/vehicle dynamics simulation environment resulted in 9.5% fewer traffic conflicts as compared with the microscopic traffic simulation model only approach. The results of the two conflict estimation approaches, from the (1) proposed integrated approach, and (2) microscopic traffic simulation model only approach, were analyzed to estimate their correlation with the actual traffic crashes. These correlations were then used to compare the effectiveness of these approaches in assessing surrogate safety. This analysis from the research reported in this paper 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). 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) indicating that the newly developed vehicle dynamics model-integrated surrogate safety simulation environment is a superior and valid alternative in assessing the surrogate safety.