Traffic Control Preplans For Freeways

With the development of freeways in China,the mileage of freeways has reached 117,000 kilometers as the end of 2015.The increasing traffic demand lead to the heavily freeway traffic volume,more traffic accidents,shorten maintain cycle,and road work.Deal to lack of traffic control,traffic incidents will have a serious impact on road traffic once they occur.Closed road facilities lead to longer duration traffic congestion;The shuck reduction of speed is easy to trigger secondary accidents such as multi-vehicle rear-end collision.In order to reduce the impact of traffic accidents,we need to seek a traffic control method which available to the traffic condition of freeways in China.In recent years,Active Traffic Management(ATM)technology has been employed to prevent block and secondary accidents.However,more researches focus on the control model and the algorithm,and less is on the application technology.By introducing the ATM technology and combining the traffic condition of the domestic freeways,this paper proposes on the preplans based of VSL control method in freeways.The variable speed limit control preplans for different control spacing and flow combination condition through the simulation experiments.The paper firstly conduct analyses of traffic accident statistic,the impact of the traffic incidents and the road work,the traffic flow characteristics etc,which lays the foundation for the control preplans research.The conclusion of obtaining the information of traffic accidents and the choice of traffic control technology,and determines the key parameters range such as the final speed limit value,speed limit gradient and speed limit spacing in the control preplans.The simulation experiment scheme is designed and the parameters is calibrated.And determines the smoothness indices and safety indices are determined for the control preplans evaluation.Then the simulation research and the analyses of experimental results of short-and-long spacing control preplans.The results shows that the short spacing control preplan can increase the smoothness and the safety indices 37% and 28% respectively at most;the long-spacing control plan can maximize improve the smoothness and the safety indices 41% and 59% respectively at most.The finding is expected to provide reference for freeways traffic control in our country.This paper has a remarkable effect on traffic congestion and reduction secondary accidents caused by the reduction of transportation incidents and road works.The result form simulation method in this paper would be improved by the real data collected after the implication of proposed control preplans.