Research On Isolated Intersection Adaptive Control Method Based On Risk Analysis

Intersection is the basic control unit of urban road system.Many risk factors at intersections threaten the safety and efficiency.Traffic signal plays an important role in intersection safety.However,most signal control systems aim at traffic efficiency,and few control models comprehensively consider the intersection risk currently.Therefore,based on the analysis of intersection risks,this paper explores an adaptive control method that comprehensively considers traffic efficiency risk and safety risk,and designs the special control strategy and scheme when the lane is occupied,so as to prevent and mitigate the intersection risk as much as possible.The paper considers the intersection risk from safety risk and efficiency risk.Firstly,the paper makes a qualitative analysis of the risk factors of an urban road intersection.The risk source structure of the intersection is constructed.Then VISSIM and SSAM software are used to analyze dynamic risk factors such as signal control and traffic flow characteristics.The influence of lane occupation on traffic flow is also discussed.On this basis,a traffic safety risk index considering the number and severity of phase conflict is established.The efficiency risk index based on vehicle delay is selected.Furthermore,an adaptive signal control method including normal state control and special state control is proposed.For the normal traffic state,the control principle of scheme selection is adopted,and the scheme of green signal ratio and the small step adjustment of cycle are selected for the real-time traffic flow.When there is a special traffic condition in which the lane is occupied,the corresponding control scheme is set according to whether there are other available lanes in the occupied lane group.Finally,taking the intersection of Hefei demonstration area as a case,the timing optimization model and the timing method based on the conventional delay model are respectively used for timing design.The MATLAB-VISSIM simulation platform is built through COM interface.The adaptive control method based on normal state risk is simulated,and the simulation results of timing control are compared.The simulation results show that when the traffic demand is not high,the timing optimization model based on the risk index can effectively reduce the intersection operation risk under the timing design of the conventional delay model.In addition,compared with the fixed time signal control,the adaptive control method designed for the normal state risk has good applicability for the traffic flow with low saturation,and it has a better effect on the number of phase conflicts and delay.