高速公路可变限速控制策略多目标优化

Variable speed limit control is an important part of active management and control technology of expressways. It dynamically updates the speed limit value according to the road operating conditions and effectively controls the traffic flow state. Due to the impact of traffic incidents, it is still a challenge to design a variable speed limit control strategy considering the efficiency and safety of traffic operations simultaneously. With the spatial characteristics of highway traffic flow under the influence of traffic incidents, we improve the basic Cell Transmission Model (CTM) model by extending the variable length of cells and integrating metastable state theory. Considering the decrease in traffic capacity in bottleneck areas under the influence of incidents and the change of speed under traffic control, a variable CTM model is constructed. To balance traffic efficiency and safety in practical applications, a multi-objective optimization method of the variable speed limit control strategy with the objective of shortest total travel time and minimum total collision risk is proposed, and the NSGA-II algorithm is applied to solve the optimization problem. The Ganggou-Xinglong section of the Jinan Ring Expressway was selected as the case study. The simulation scenario was constructed and adjusted based on the actual traffic flow data. A comparative experiment under different conditions, with different cell numbers and speed limit control cycles, was designed. The results show that the proposed method can effectively reduce the total travel time by more than 32% and the total collision probability by about 70% under the influence of the incident, which can effectively improve the efficiency and safety level of road traffic. At the same time, the advantages and disadvantages of the number of cells and the length of the control cycle of the speed limit were compared and discussed. © 2023 Science Press. All rights reserved.