Lane change decision model of expressway exit ramp with heterogeneous flow mixing autonomous vehicles

ObjectiveThis study aims to overcome the unrealistic limitations of fixed acceptable gap theory in vehicle diversion and lane change. It also addresses the large variations in vehicle diversion and lane change behavior with heterogeneous flow. An improved exit ramp lane change decision model adaptable to heterogeneous flow is therefore needed.MethodFirst, characteristics of actual vehicle diverging decision behavior were analyzed. Lane change urgency was incorporated into the acceptable gap theory. Next, segmented and continuous variable acceptable gap diverging lane change decision models were constructed separately, corresponding to the distinct driving behaviors of human-driven and automated vehicles. Finally, simulations were conducted through SUMO to evaluate the model's effects on traffic safety and efficiency with different heterogeneous flows. The model was also evaluated through a comparative simulation with SL2015 lane change model.ResultCompared with SL2015 lane change model, the proposed model reduces the speed variation coefficient by 23.13%, and improves the relative access efficiency by 12.09%. Applying this model, the congestion in exit ramp diverging zones is alleviated, and the vehicle speed fluctuations are reduced, leading to better traffic safety and higher traffic efficiency.ConclusionThe proposed model simulates the dynamic variation of acceptable gap for vehicle diversion in traffic scenarios. It unifies the vehicle diverging lane change behavior characteristics with heterogeneous flow. This study provides a theoretical basis for study on vehicle diverging behavior in such environments.