Analysis Of The Vulnerability Of Key Nodes And Sections Of Mountainous Urban Road Networks To Road Networks

With the rapid development of urban transportation and the continuous improvement of people’s living standards,the increase in the number of motor vehicles nationwide has caused the conflict between residents’ transportation demand and urban road supply to increase.Once the traffic volume of the urban road network exceeds the maximum capacity of key intersections and key sections of the road network,traffic congestion will occur at key intersections and key sections.And then the congestion will be transferred to adjacent intersections and sections through the road topology network,causing the failure of the cascade led to the paralysis of the entire road network.In this regard,due to the complex terrain of mountainous cities,its road network is more likely to cause cascading failures than plain cities.In this regard,the paper conducts a research on the identification of key nodes and key sections of the mountain city road network,aiming to explore the impact of different characteristics of key nodes and key section failures on the vulnerability of the road network,and provide reference for the urban traffic management department in the management of urban road networks.The main work of the thesis is as follows:1)From the three aspects of urban road network research history,urban road network key nodes and key road section identification research,and mountain city road network research status quo,domestic and foreign research is reviewed,the existing research theories and methods are analyzed,and the deficiencies of existing research are summarized.Determine the feasibility of the thesis research.2)Complexity analysis of road network in mountainous city and construction of road network model.From the perspective of dynamic and static characteristics,the basic theory of complexity analysis of mountain city road network is introduced.Qualitative and quantitative methods are used to describe the spatial and traffic characteristics of mountain city road network,providing theoretical support and technical support for follow-up research.Next,take the road network of a certain area in Yuzhong District of Chongqing as the research object,consider node types,inter-node link flow and link level,road location attributes,actual distance between adjacent roads and road level,using network analysis software Pajek,respectively based on the original graph theory method and dual method to establish node network and road segment network.3)Research on identification of key nodes and key road sections.The adjacency information entropy theory and the RAPA algorithm are compared with the importance evaluation matrix algorithm and the PA algorithm respectively,and the effectiveness of the two model algorithms in the thesis is verified.The adjacency information entropy theory and the RAPA algorithm are respectively applied to the node network and the road section network to identify key nodes and key road sections.And finally 30 key nodes and 27 key road sections are identified.4)Vulnerability analysis of road network in mountainous cities.From the perspective of four types of network disturbances: different types of node failures,different node attack methods,different functional road sections,and different road section attack methods,combining the relative size of the largest connected subgraph of the network and the network efficiency two indicators,respectively,the node network and the road section network conducts network vulnerability analysis,draws relevant conclusions,and gives recommendations for the protection of key nodes and key road sections of the road network.