Research On The Traffic Organization Optimization In The Micro-circulation Of The Urban Road Network

In recent years,urban traffic congestion is increasingly becoming a problem that transportation planning and construction experts faced.The construction of new roads,road widening,intelligent transportation systems and traffic organization and optimization is the most commonly used strategy to solve the traffic congestion,and these measures have a certain effect.Most traffic congestion problems occur on major roads and intersection node,however,the branch utilization is very low.Therefore,improving the existed urban traffic micro-circulation system gradually is a new method deserved to explore to solve the traffic congestion in the area.The urban traffic microcirculation system can disperse the pressure and reduce the flow,balance the overall road network flow and save the soil resources.Therefore,whether the design of the micro-circulation system is reasonable will be directly related to the traffic flow in the major roads can be attracted to the branch road and the traffic efficiency in the road network can be improved.This paper puts forward the optimization model of the traffic organization in the micro-circulation road net and the algorithm by summarizing the design theory of the existed micro-circulation system.First of all,the basic concept of the urban traffic micro-circulation system is put forward,which is analogous to the blood circulation system in medical system.The style of the micro-circulation is classified from the effected scope,the duration,the traffic carrier,the road direction,the travel purpose and so on.The functional characteristics of the traffic micro-circulation system is summarized,such as the traffic pressure transition,accessibility and solving the area traffic congestion.Finally,it discusses the traffic demand,traffic flow,traffic organization and optimization of the three major micro-circulation traffic characteristics.Secondly,according to the traffic demand,the traffic flow and the traffic organization characteristic of the micro-circulation network,the existed traffic problems in the road network are analyzed.A bi-level programming model for multi-objective optimization is established,which takes the minimization of the area average saturation in the major roads,the area major roads saturation ultra-limited and the average saturation of branch roads as the optimization goal.The decision variable of the model is the direction of traffic organization in the branch road of the micro-circulation network.The lower level is conformed to the user equilibrium assignment model under the restriction of the traffic flow in the branch road section and the capacity and saturation of arterial road.The decision variable of lower level programming model is the traffic flow of each branch road.Again,the advantages and disadvantages,the scope of application and the application of the principle is compared and analyzed.The genetic algorithm uses the actual value of the decision variables to the coding analysis,and takes the fitness function as the index to search the information of the solution collection,which improves the efficiency of the algorithm.Based on the simple efficient and robust characteristics of the genetic algorithm,this paper designed the genetic algorithm to solve the model,and obtains the traffic organization optimization scheme in the road network micro-circulation.Finally,aiming at the present and optimized situation of the micro-circulation network traffic organization optimization scheme,the macro simulation software TransCAD is used to establish the macro modeling,and the simulation of parameters such as the traffic volume and the running scheme of the path are extracted to construct the micro-simulation Vissim model.The delay,queue length and other traffic parameters is outputted.The method of the grey multi-hierarchy comprehensive evaluation is used for evaluating the optimization scheme of the road network microcirculation with the help of the MCE software.After analyzing the current and optimized situation micro-circulation network traffic organization scheme,the effectiveness and rationality of the optimization of micro-circulation network traffic organization is verified.