高速公路长隧道入口段可变限速研究

On the control of the variable speed limits at the long tunnel freeway entrance

为提高高速公路长隧道入口段的交通安全,缓解驾驶人生理心理不适,对入口段实施可变限速控制策略。采用宏观交通流模型,以事故率最小为目标,以速度限制为约束条件,建立可变限速控制优化模型,并采用遗传算法对整个可变限速模型进行求解,确定可变信息板数目与相应的可变限速值。基于采集的交通流数据,运用微观仿真软件对长隧道入口段实施可变限速控制,并与未实施可变限速的情况进行对比。结果表明:对高速公路长隧道入口段实施分区间可变限速控制,在无交通事故的情况下,能够减少车辆运行速度的离散性;若隧道内发生事故,能够减少26.67%车辆停车次数和21.13%的平均旅行时间。研究表明,对长隧道入口段实施可变限速控制,能够提高交通安全,提高交通的运行效率。

This paper intends to propose a dynamic control strategy to regulate the vehicular driving speed at the long tunnel entrance on the freeway, which is often considered to be a black spot for a driver. As is well known, it is of great necessity to implement variable speed control strategies in such entrance areas so as to improve the opera- tional efficiency and ensure the traffic sMety over there. For the said study purpose, we have decided to use macroscopic traffic flow model to simulate the traffic flow currency because what is needed is make merely a limited series of systematic efforts and the corresponding cal- culation statistics to ameliorate the situation in-situ. Given that the safety is a goal for traffic management based on the need for minimiz- ing the accident rate and improve the road conditions and velocity change as the constraints, the paper has established a variable speed- control optimization model with the help of the genetic algorithm, a kind of optimized algorithm, which has enabled us to find the global optimal indexical parameters needed for the model. And, with the said model, it would be easy for us to determine the number of vari- able message boards and variable speed control constraints. Based on the traffic flow control data, we have adopted a micro-simulation soft- ware to simulate the execution of the variable speed limits at the tun- nel entrance. What is more, we have also simulated the direct imple- mentation without any variable speed limits. Comparing the data with- out variable speed limits, we have arrived at the following conclusive ideas： （1） Trial implementation of the variable speed control at the long tunnel entrances of the freeway can reduce the dispersion of vari- able running speeds in the absence of a traffic accident case; （2） the number of parking vehicles can be reduced by 26.67 % and 21.13 % of the average travel time when the traffic accidents occur in the tun- nel. The above said results show that the implementation of variable speed controls at long tunnel entrance can improve the traffic safety and operational efficiency. Therefore, the result of this paper expect- ed to serve as theoretical reference to the freeway project design and construction in the field.