Timing Optimization Research Of Urban Intersection Based On Bus Priority

Along with the rapid development of social economy and transformation of traffic trip concept, contradiction between supply and demand is aggravating in urban traffic. Traffic congestion and accidents as a representative of the traffic problem is increasingly serious. Bus priority has gradually become the consensus of cities to ease traffic congestion and improve traffic efficiency. Bus priority signal control as the main measures of bus time priority, is vital to reduce the bus delay and improve transit efficiency.The thesis considers the urban intersection as research object, intersection timing optimization based on bus priority is studied through a lot of traffic investigation and analysis. Separately, timing optimization model in the condition of single priority request and multiple priorities requests are proposed based on approach flow description and delay analysis. Intersection investigation data are applied to model analysis. In this thesis, main work is as follows:(1)The thesis calculates minimum cycle time and maximum cycle time of intersection based on Webster timing method. Take the average passenger delay minimization as the object function in each phase, an optimal search method is provided to optimize the cycle time. Consideration the traffic efficiency of passengers, methods of phase split calculation and priority strategy time optimization are proposed to distribute the surplus green time in each phase.(2) Characteristics of truncation, rectifier and aggregation in the intersection is discussed based on flow characteristic analysis. The thesis proposals a fitting function calculation method based on the linear least squares fitting method, and The fitting precision is compared under the intersection delay.(3)Strategic rule is proposed under the single priority request based on green extension, red reduction and phase insertion strategy. The traffic delay is calculated in geometrical analysis method based on the curve of traffic accumulation and dissipation. Consideration the constraint of minimum green time in each phase, the thesis establishes a time optimal model based on passenger delay minimization.(4)According to different green time demand, Priority strategy combinations, green loss equilibrium methods and delay calculation formula are proposed in the condition of multiple priority requests. Priority strategies are optimized based on the queuing delay of intersection and the downstream station in the upper model, the process of vehicles acceleration delay optimization is described in the lower model. An algorithm is proposed to solve the Bi-level programming model.