Research On Cascading Failure Of Urban Road Network Based On Complex Network Theory

In the urban road traffic network,it is often encountered that some road segments and intersections fail in a short period of time due to natural disasters or traffic accidents,which in turn affects the large-scale congestion of the traffic network.This phenomenon is called cascading failure in complex networks.It is of great significance to study the cascading failure phenomenon of urban road traffic network for preventing large-scale paralyzed traffic and improving the reliability of road network.It is more reasonable to screen the important road segments and intersections in the road network considering the impact of cascade failure.This paper is based on the study of the cascading failure of urban road traffic network.The main research work is as follows:(1)Firstly,the primal approach is used to construct the geometric topology map of the urban road traffic network.Based on the existing load-capacity model,this paper improves the initial load definition of the model and the rules for the redistribution of failure load in consideration of the directionality of the urban road traffic network and the local diffusion characteristics of the congestion.The failure of the intersection in the urban road traffic network is equivalently converted into the failure of the road segment,and the edge failure model and the node failure model of the urban road traffic network are constructed.Then the constructed model is used to simulate and analyze the failure of different segments and intersections,and this paper examines the diffusion process of congestion after different segments and intersections are damaged.Besides,the ratio of the average distance reduction of the road network after being damaged and the proportion of the affected road segments are used to reflect the destruction degree of the road segments and intersections.(2)Analyzing the topological attributes of the road network segments and intersections from from the degree,the betweenness,the proximity and the clustering coefficients and other indicators,and analyzing the failure effects from the degree of damage,this paper constructs the evaluation model for road segments and intersections in urban road traffic network.Finally,the fuzzy clustering method is used to cluster the road segments and intersections.The conclusion shows that it can't accurately judge the importance of road segments and intersections only considering some static indicators of road segments and intersections.It is more reasonable to cluster different road segments and intersections in consideration of various indicators because there are still some important road segments and intersections in the road network.(3)The regional road traffic network in downtown Dalian is analyzed as an instance.Firstly,the topology network diagram is constructed for the selected road network.Secondly,the characteristics of the road network are analyzed from the degree distribution of the road network,the distribution of the betweenness,the average distance of the road network,etc.Then each segment and intersection in the road network is carried out to analyze the failure impact process to verify the feasibility of the improved cascade failure model.And the relationship between the topological properties of the road segments and intersections and the failure impact results in the road network is compared and analyzed.Finally,this paper evaluates the road segments and intersections in the road network combining the evaluation system for the important segments and intersection constructed in this paper.Furthermore,the fuzzy clustering method is used to divide the segments and intersections in the study area.