Research On Traffic Signal Control Methods For Urban Road Intersections

The deepening of the urbanization process and the continuous improvement of people's living standards have brought increasing pressure on urban road traffic.Take effective traffic signal control and management,by adjusting space-time distribution of vehicles,can improve road utilization and ease the problem of urban congestion.In this paper,the evaluation indexes and control strategies are designed around traffic evaluation of intersections,signal control of isolated intersections and the coordinated control of multiple intersections.With traffic information to clarify traffic conditions and develop adaptive control programs to achieve the purpose of improving traffic conditions and efficiency.The specific work of this paper is as follows:For intersections under emergencies,classification control strategy based on non-linear comprehensive index evaluation is designed.To reflect impacts of lanes traffic change on the intersection,traffic indexes were redefined with weighted coefficient method.To evaluate intersections from multiple perspectives,processing multiple indicators through non-linear synthesis method and forming a two-norm composite index.Intersections are classified and controlled based on evaluation results to ease the pressure of intersection at different congestion levels.To improve efficiency of PSO,nonlinear inertia weight and average information of particle swarm are considered.The improved algorithm is used to optimize the objective function to get optimal timing.It is verified that the proposed signal control strategy can make effective use of traffic data,comprehensively and accurately evaluate the traffic conditions at intersections and reduce the traffic congestion.For dividing control subarea of road network,partition of intersection group based on traffic demand and correlation degree is designed.Through the least squares method to improve queuing farthest model to advance its accuracy.Quantify traffic demand and dynamically determine the key intersection with model above.To enhance engineering application ability of calculation formula of correlation,the difference of period is introduced to it with inverted S-shaped function.By referring to hierarchical clustering,this paper proposes a hierarchical division algorithm for demarcating intersection group range.The proposed partitioning method realizes the dynamic quantitative partition of control sub-area.For signal coordination of intersections on a polygonal path,a control scheme based on the minimum delay and saturation is designed.To optimize phase differences,vehicle delay at signalized intersection was analyzed and extended to establish phase-difference optimization model of the path.To improve traffic distribution at intersections with uneven traffic flow and reduce saturation of each section,a green-signal-ratio optimization model is established by means of equalization saturation.Finally,the PSO algorithm and fmincon function are respectively used to solve the phase difference and green ratio optimization model.The proposed method achieves the coordinated control of multiple junctions on the polygonal path and improves traffic efficiency on the coordinated path.