Modeling Evolutionary Network Of Urban Subway Systems And Cascading Failure Over Urban Subway Systems

In the process of modern city development, the urban traffic capacity has become one of important factors that restrict economic vitality. Therefore, many cities are building their subway systems, In the first part, we construct the evolution model of ten urban subway systems, analyze the evolution of main network properties with the development of subway system. Our investigations show that the average path and diameter of network increase sharply at first, then maintain a stable value with the formation of the core-branch structure of subway systems. We also analyze the relationship between degree and betweenness centrality (BC), find that there is a positive correlation between them. Whereas, there are some nodes stations with low degree having high BC, which are often located near the ring line and undertake more passenger flow. Furthermore, our results show that the formation of local loop leads some stations reduce their BC with the development, which indicates that local topology is improved as the evolution of subway system. Finally, we analyze the distribution of loops, find that55%of edges don’t belong to a loop.In the second part, we analyze the features of cascading failure process in the subway systems and provide valuable suggestions for the construction and protection of subway systems. Based on the complex network theory, we analyze the node centrality using different methods, such as BC and Degree, then discuss the subway systems’ performance under random failures and intentional attacks respectively, our investigations show that the robustness under random failures is better than that under intentional attacks, as that in the scale-free networks. We also shows that the robustness sometimes becomes worse as the tolerance parameter a increases. To interpret the reason, we analysis the cascading failure process. At last, we give several suggestions, which help us to improve the robustness of the subway systems.In the last part, based on nodes’ BC and position, we propose an indicator of centrality and compare it with BC and Degree. The results show that position information should be taken into account.