Control Method of Variable Speed Limits at the Freeway Tunnel Entrance under Rainy Weather

According to the real-time traffic flow state and rainfall intensity of the freeway, this paper intends to propose a dynamic control strategy to regulate the vehicular driving speed at the tunnel entrance on the freeway to reduce the adverse effects of rainfall. In this paper, variable speed limits control optimization model for rainy days, which is with the minimum accident rate as the objective. The speed limit as the constraint condition is established, and the whole variable speed limits model is solved by genetic algorithm. Based on the traffic flow data, the micro simulation software is used to simulate the execution of the variable speed limits at the entrance of the tunnel, and the comparison is made with the situation that the variable speed limit is not implemented. The results show that in rainy days, compared with the fixed speed limit mode, the implementation of variable speed controls at tunnel entrances can significantly reduce the dispersion of variable running speeds, which are advantageous to traffic safety and operational efficiency.