A Control method of Dedicated Lanes for Mixed Use of Special Vehicles and CAVs Based on Dynamic Clear Distance

Providing road priority to special vehicles is one of important tasks of traffic management and operation authorities. However, traditional control measures for providing road priority to special vehicle are difficult to implement, and they also tend to significantly reduce road capacity for other traffic. Therefore, a control method of dedicated lane for mixed use of special vehicles and connected automated vehicles(CAVs), is proposed to solve the above problems. First, the access rules for the dedicated lanes in the order of emergency vehicles, vehicles with secondary priority and CAVs are designed. By predicting the queue length when special vehicles arrive at a downstream intersection, the state of special vehicles at the intersection is obtained, and a dynamic clear distance model is developed to meet the demand of special vehicles with different priorities. In this model, the objective function is to minimize the speed reduction of emergency vehicles, and to balance the road capacity with traffic demand of the vehicles with secondary priority. The rules for CAVs to enter and leave the dedicated lanes are designed, and a lane-changing control model is established to solve the problem that CAVs may become obstacles to other vehicles at dedicated lanes. With the above, a dedicated lane control strategy suitable for different types of vehicles with different priority is proposed. The effectiveness of the model is validated through a set of simulated experiments. Study results show that, compared with the control methods without consideration of the priority of special vehicles, the average travel time and per capita travel time are increased by 3.9% and 2.8% respectively, but the average vehicle delay of special vehicles is reduced by more than 59.6%. Compared with the intermittent bus lane control method, the average vehicle travel time and per capita travel time are reduced by 16.7% and 14.6% respectively, and the average delay of special vehicles is reduced by 13.5% and the use rate of special lanes is increased by more than 36.3%. The best outcomes can be obtained when the CAVs penetration rate is greater than 40%. The proposed method removes some of the limitations of traditional lane control strategies when providing road priority to special vehicles, and therefore, provides"new"theoretical contribution for traffic control and management.