Study on Structural Characteristics of Urban Rail Transit Loop Line: A Case Study of the Xi’an Subway

With increased construction of urban rail transit (URT) in China, loop-lines are becoming more common and symbolic of the level of rail transit networks (RTN) in various cities. In order to evaluate urban rail transit loops, this paper applies the study of complex networks to URT network analysis, considering both topological and metric properties. The structure of Xi’an RTN is analyzed by using L method, P method, and the fractal model, and the relationship between urban rail network structure and urban passenger flow characteristics is established based on structural features. The results show that the loop increases the connectivity, accessibility, and robustness of its network (effectively improving the transfer efficiency of the whole network), strengthens the connection of the passenger flow distribution points at the center edge, and cuts off relationships between the peripheral areas to reduce traffic pressure in the central area.