Safety First

Abstract

Prevailing traffic conditions affect highway safety and the processes by which drivers perceive a stimulus, evaluate it, and execute a corresponding driving maneuver. Several efforts have been made to use microscopic traffic simulation for evaluating highway safety. However, these efforts faced serious challenges because previous acceleration and lane-changing models had been built in an accident-free environment with different layers of safety constraints. A new approach relies on a cognitive risk-based microscopic model to study the relationship between prevailing traffic conditions and the risk experienced by drivers in a traffic stream. The model can consider accidents endogenously through lane-changing logic and provide an indicator of relative roadway safety as experienced by drivers. Six scenarios are simulated. The results show the importance of lane changing to understanding accident and near-accident occurrence in simulation models. A risk value comparison reveals that work zone bottlenecks have a greater impact on drivers’ risk-taking tendencies than bottlenecks caused by uphill grades.