Integrated Variable Speed Limit (VSL) and Ramp Metering (RM) Control Strategy Based on Optimal Collision Probability Prediction

Traffic congestion and collision problems had been focused widely by transportation researchers. Various traffic management strategies such as Variable Speed Limit (VSL), ramp metering (RM), etc., have been deployed to mitigate traffic congestion and collision. However, most previous studies focused on the impacts of VSL or RM control separately. Therefore, in this study, a model predictive integrated VSL and RM control strategy based on collision probability optimization was proposed. The proposed control strategy predicts future traffic states and collision probability, and considers the optimum VSL and RM input simultaneously by minimizing collision probability. To quantify the safety and mobility impact, the proposed integrated control was implemented in microscopic simulation and compared with VSL control, RM control and without any control scenario respectively. The results indicate that the integrated VSL and RM control strategy can improve safety by approximately 41% and mobility by approximately 13%. In conclusion, the proposed integrated VSL and RM control strategy was better than VSL control strategy and RM control strategy independently.