Study On Integrated Control Method Of Traffic Flow Confluence On Expressway

A number of studies have shown that the area where highway traffic flows into is a bottleneck area and an accident-prone area.At present,significant changes have taken place in highway information collection technology and methods and bring the possibility of further optimization of traffic control technology.Combining multiple control strategies to form integrated control has practical significance for improving traffic safety and traffic efficiency.This thesis starts from the impact mechanism of traffic control technology on traffic flow,carries out optimization and designs research around different control strategies.The main work is as follows:The traditional ALINEA ramp metering algorithm is optimized to enture the smooth flow of traffic on the main line and reduce the length of the ramp queue.By analyzing the impact mechanism of ramp metering on traffic flow,it is pointed out that ramp metering strategy formulation should consider ramp queuing constraints and driver tolerance.The DBN model is selected to predict short-term traffic flow on the ramp.The ramp queuing constraint conditions considering the driver’s tolerance are given.The COSCAL v2 algorithm is extended.By analyzing the impact mechanism of variable on traffic flow through real data,it is pointed out that the instantaneous speed control control effect is better.In order to dissipate the shock waves generated by congestion and improve the adaptability of the algorithm in the real environment,the COSCAL v2 algorithm considering driver compliance is designed based on the feedback-reward/penalty mechanism.Based on the above research,the ALINEA controller structure and the COSCAL v2 algorithm controller structure are given.On this basis,the two control algorithms are combined to design a feedback integrated controller structure.Then,a feedback integrated control strategy and framework are given to enture that the efficiency of the main line is improved while reducing the length of the ramp queue.Further,a control system based on vehicle and infrastructure cooperation is designed for ramp control and variable speed limit control.On this basis,the two control systems are combined to form a feedback cooperative control system based on vehicle and infrastructure cooperation.And the purpose is to verify the adaptability of various control algorithms in vehicle and infrastructure cooperation environment.Based on the above research,examples are selected to verify that the object to evaluate and analyze the control strategy.The experimental results show that:(1)The improvement of ALINEA ramp merering in the conventional environment and the vehicle and infrastructure cooperation can reduce the total travel time of the main line by 7.1% and 10.2%,and it can reduce the queue length of the ramp by 25% and 48.9%;(2)In terms of traffic efficiency,the feedback integrated control strategy proposed in the conventional environment can reduce the total travel time by 19.2% and the vehicle waiting in the acceleration lane by 56.2%.In terms of traffic safety,the feedback integrated control strategy can reduce the speed standard deviation by 40.8% and eliminate the cars’ “stop and go” phenomenon,which means that the vehicle has a lower risk of collision;(3)The feedback integrated control strategy used in the vehicle and infrastructure cooperation environment can eliminate the hysteresis effect,and the control efficiency is better.