Analysis and Modelling of Passing Sight Distance Using Vehicle Dynamic Response

Passing Sight Distance (PSD) is pivotal for two-lane undivided highways, impacting their safety and operational performance. However, current PSD standards and models are based on simplistic assumptions and do not consider road characteristics and vehicle dynamic response. This study investigates the adequacy of PSD models in practice by comparing them with more realistic values obtained from IPG CarMaker®, a commercial vehicle and traffic simulation software. Similar test variables are chosen to compare the simulation and standards consistently. Since road gradient and road-tire friction affect the acceleration capabilities of vehicles, their effects on PSD are analysed by configuring the parameters in the simulation. High deviations of up to 94% are observed in the PSD values compared to the existing model under different road conditions. In the paper’s second half, the existing model is evaluated for its performance in mixed traffic conditions by comparison with empirical data. Followed by this, an analytical model for PSD is proposed, which considers vehicle dynamic response. This model allows parameter selection and the application of physical vehicle constraints, considering the microscopic behaviour of a vehicle during an overtake. The deviations observed in PSD values obtained from this model are within 5% for the specified test cases simulated in the vehicle dynamics simulator. Furthermore, the model is benchmarked against existing models using field data, demonstrating its superior performance in terms of feasibility and safety. The accurate replication of overtaking manoeuvres by the analytical model will have significant implications for geometric design, traffic operations, advanced driver assistance, autonomous vehicle applications and policymaking.