Research On Route And Capacity Redundancy Of Urban Road Network

The transportation network,which is the artery of urban economic and social development,is essential for maintaining the normal functioning of the city with a stable,efficient and safe features.However,redundant design of road or nodes is often neglected in road network planning,which result in large-scale disintegration of network in emergencies.Therefore,it is necessary to improve the theory of redundancy in the field of transportation,in order to solve the two key problems of "how many effective redundant paths can be provided" and "how much redundant capacity can be provided" when a link or node fails,and to further study the route and capacity redundancy of urban road network.Firstly,this thesis expounds the research results of redundancy theory in various fields,and puts forward the redundancy index considering path diversity and network capacity,which is path redundancy,road capacity redundancy and node capacity redundancy.The path redundancy is used to represent the change of feasible and reasonable paths number in the network before and afier road failure,while the capacity redundancy characterizes the influence degree of the road or node on the system capacity before and after the damage,and describes the definition and calculation formula of the index.Secondly,the corresponding measurement method is constructed to measure the redundancy index of the traffic system.For the path redundancy,the stochastic user equilibrium assignment that based on the feasible and reasonable path is used to obtain the number of feasible paths in the network before and after the link failure,and the path redundancy is obtained,which is verified by Nguyen-Dupuis network.In view of capacity redundancy,the travel cost functions of various traffic modes in multi-mode network are analyzed,and a bi-level programming model of multi-mode network capacity is established.The upper level planning is to maximize the capacity of the traffic network considering the capacity constraints of roads,and the lower level is a combination model of mode partition and traffic assignment based on multi-mode,and the incremental method and successive averaging method(MSA)are used for the algorithm.After obtaining the network capacity before and after the failure of the road or node,the road capacity redundancy and node capacity redundancy are determined according to the index calculation formula,and verified by the multi-mode design network.Finally,the thesis analyzes the application of road network redundancy in traffic planning and management,and proposes a route import,ance ranking method based on path redundancy and travel efficiency,and presents the method of determining the optimal sequence of road networks based on capacity redundancy of road segments and identifying key nodes of road networks based on capacity redundancy of nodes.The feasibility of these methods is verified by examples,which can provide theoretical basis and technical support for road network capacity judgment and bottleneck section identification.Carry out redundancy analysis is helpful to make up for the lack of redundancy research in the traffic field,and can provide new ideas for the identification of key nodes and important road sections,and help to improve the scientific level of traffic planning and management decision-making.Its research has important theoretical significance and practical application value.