Variable speed limit control strategy at the entrance and exit of freeway tunnel

In order to effectively reduce the accident rate of freeway tunnel section and improve the safety factor of tunnel section, variable speed limit control scheme at the entrance and exit of tunnel is presented from the perspective of safety. First, by considering the influence of tunnel section characteristics on vehicle operation, variable speed limit cells and variable length cells are added to improve the cell transmission model and establish a dynamic traffic flow model; Second, aimed at the minimum speed dispersion and the minimum change rate of tunnel illumination, and taken the fixed speed limit and the maximum speed difference as constraints, the variable speed limit control optimization model at the entrance and exit of the tunnel is established; Third, the genetic algorithm is employed to solve the control function with meeting the safety requirement of traffic operation. The results show that compared with the fixed speed limit mode, the implementation of variable speed control in tunnel group sections can significantly reduce the dispersion of running speed, which is conducive to traffic safety and operation efficiency.