Evaluating the evolution of subway networks: Evidence from Beijing Subway Network

As one of the largest subway networks, the Beijing Subway Network has developed with an unprecedented velocity during the last seven years. This paper analyzes the evolution of the Beijing Subway Network during this high-speed period and proposes a new growth model, composed by an expanding mode and an intensifying mode. The two modes appear alternatively so that the network can become larger and denser. However, the expanding mode is more influential from a long-term perspective while the effects of an intensifying mode are more observable in the short-term. Moreover, in order to better understand the characteristics of subway networks, this paper uses a weighted network of lines to define and evaluate networks. Besides the weighted clustering coefficient, the number of possible paths shows better performance in measuring the development of these networks and reveals clearly the evolution of the Beijing Subway Transfer Network.