Impact Analysis on Vulnerability of Existing Network of Urban Rail Transit Connected with New Lines—A Case Study of the Beijing Metro

With the increase of passenger flow pressures, metropolises reduce traffic pressure by adding new lines. To ensure the rationality of new lines, it is necessary to analyze the impact of different line types on the vulnerability of the existing rail transit network (RTN). Firstly, the new lines are divided into several types. Then, the models of different line types connected to the rail transit network are established by the L-space method. Moreover, a new method that comprehensively evaluates the rail transit network vulnerability based on the index of average shortest path length, network efficiency, and average node betweenness is proposed. Finally, taking Beijing as an example, obtain the influence characteristics on the vulnerability of Beijing rail transit network (BRTN) connected with different line types. The results show that the ring line can effectively reduce the vulnerability of the network compared with a penetrating line and outskirts extension line.