Study On Reliability And Planning Strategy Of Railway Network In Chengdu-Chongqing Urban Agglomeration

Railway network has the characteristics of large carrying capacity,low running cost,safe,punctual,and less energy consumption.In the large flow of passenger transport,it has a very obvious advantage.The rapid development of economic construction puts forward higher requirements to the reliability of the railway transportation security.The disaster happens frequently in the Chengdu-Chongqing urban agglomeration,and the terrain is very complex.Taking into account the reality that railway transportation is facing public and rapid,the safty of railway transportation is very important and has become a part of the lifeline engineering of regional coordinated development.Therefore,by using the complex networks theory and methods in the field of urban and rural planning,and grasping the complexity and the dynamics of system response characteristics,the reliability of railway network of Chengdu-Chongqing urban agglomeration was analyzed and evaluated.What's more,regional planning response strategies were proposed.First of all,the development process and the main security problems of Chengdu-Chongqing urban agglomeration railway network were analyzed.The development of the railway network of Chengdu-Chongqing urban agglomeration could be summarized as the following four stages: the steady development stage(1950-1979),the optimization stage after the reform and opening up(1979-1997),the extension stage after Chongqing became municipality(1997-2005)and network stage(since 2005).The main safety problems were caused by frequent disasters,such as line interruption,cascading failure caused by line fault,unbalanced regional distribution of railway network and low operation efficiency of regional connectivity.Secondly,by using the complex network theory,from two aspects of traffic infrastructure and O-D railway links between sites,undirected and unweighted railway physical network model and a weighted undirected railway traffic network model were abstracted.The topology structure reliability of Chengdu-Chongqing urban agglomeration railway network was evaluated from two aspects of statistical properties and characteristics of structure.The main conclusions are as follows:(1)Railway physical network is a tree network,and railway traffic network is a scale-free small world network;(2)Core-edge structure of railway network is obviously,and most of the nodes in the low density are distributed over the edge of the area;(3)Railway network concentrated areas are still a lack of communication.Third,the dynamic reliability of Chengdu-Chongqing urban agglomeration railway network under the network fault was studied.The index system was established and the connectivity reliability was assessed under the fault of nodes and links.The main conclusions are as follows:(1)When faced with random attack,railway network has a high ability to resist,namely robustness,while vulnerability when faced with attack judgment.(2)When network is attacked selectively in different ways,the impact on the network is significantly difference;(3)Important sites and railway sections are identified.Finally,according to the analytic results of topological structure reliability and dynamic reliability of railway network,planning strategies are put forward.Strategies are mainly discussed from the following three aspects: network structure optimization,the improvement of sites and railway sections,the optimization of railway operation and emergency management.Among them,network structure optimization includes strengthening railway connection of network concentrated areas and encrypting the rail connection between key sites.The improvement of sites and railway sections includes promotion of system site function and classification of the system sections.The optimization of railway operation and emergency management includes three aspects: raising passenger density,the first contact direction to optimize layout,planning management and the emergency response plan.In this paper,the reliability of Chengdu-Chongqing urban agglomeration railway network was analyzed and evaluated,and some suggestions were put forward for the transportation planning of railway system.It is hoped that this paper can provide some experience for the application of complex network theory in the subject of urban and rural planning.