| With the rapid increase in the level of urbanization and the rapid growth of private car ownership,the traffic flow in the main areas of the city becomes more and more dense during peak hours,especially at the intersections of urban centers around the island.Nodes,causing serious congestion inside and around the island,and resulting in low efficiency of the regional road network.Most management departments now choose to dismantle the island or increase traffic signal control.These practices can only achieve short-term effects,but do not fundamentally solve the traffic jam problem.Existing research mainly focuses on the node of the roundabout,but does not consider placing the node of the roundabout at the level of the regional road network.There are few studies to solve the traffic congestion problem of the central roundabout and the road network by allocating the traffic flow of the road network.In this paper,the urban regional road network around the island is taken as the research object,the evolution process of the traffic flow state with space and time in the selected regional road network is investigated,using the theory of traffic flow allocation,the traffic flow of the central roundabout and surrounding nodes is distributed over the entire road network,and the supply and demand of the road network's travel is balanced to the greatest extent,thereby improving the operating efficiency of the regional road network and improving the road traffic environment.First,after the preliminary data collection work,analyze the traffic status of Baotou City,determine the study area,and obtain the traffic parameters of the main roads;analyze the travel characteristics of the study area based on the license plate data,and then obtain the OD matrix between the intersections in the study area to lay the foundation for the establishment of later models and the realization of algorithms.Second,study the related theories and models of dynamic traffic allocation,including symbols,related constraints and the principles of dynamic traffic allocation,and then briefly describes and analyzes some of the solving algorithms of the dynamic traffic allocation model.Then,based on the study of the road network in the Yigong Huandao area of Baotou City,an optimal model of dynamic traffic users is established,and then the FW algorithm is constructed,and the algorithm is used to carry out example road network traffic distribution.The constructed algorithm is designed and implemented using Python.After studying the distribution of traffic flow in the regional road network,by analyzing the results of the distribution,it is concluded that the traffic flow around the roundabout after the distribution is decreasing,which improves the current traffic congestion around the roundabout.Finally,based on the PTV VISUM simulation platform,the dynamic user optimal allocation of the central road network around the island,based on the proposed FW algorithm,combined with the example of the regional road network in Baotou centered on the one-circle island centered in the road network modeling and traffic allocation.To better evaluate the effect of traffic allocation,use the VISSIM simulation platform to perform micro-simulation on before and after allocation,and then make a comparative analysis of various indicators output before and after allocation.The simulation results show that the delay of the road network vehicles after traffic allocation is reduced by 20.11 %,The number of parking on the road network is reduced by 20%,the average speed of the road network is increased by 14.03%,and the number of vehicles arriving on the road network is also increased by 5.01%;the delay of the central roundabout is also reduced by 12.96%.Traffic operation has been significantly improved. |
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