A novel evolving model of urban rail transit networks based on the local-world theory

Since the expansion of the scale of urban rail construction, the networked structure is becoming a significant characteristic of rail transit systems. For a further understanding of the networked structure, the evolution mechanism of the rail transit network is worth research and discussion. To select the most appropriate modeling space, four topological spaces (L-Space, P-Space, B-Space, and R-Space) are analyzed based on three indicators (degree distribution, clustering coefficient, and average length); P-space is selected as the basic space for topology because of its high clustering coefficient and low average length. The topological network, which is obtained by P-space, shows exponential degree distribution and local-world characteristics. After dissecting the evolution law of degree distribution and other parameters and the connection mechanism of rail transit topology, the improved local-world evolving model of urban rail transit networks (URTNs) is developed. The model is verified by its application in six cities’ rail-transit networks (London, New York, Paris, Beijing, Shanghai, and Shenzhen). The results show little difference between the real network and evolving network, with a high consistency of their degree distributions and the network indicators. These illustrate that the model can reflect the real characteristics of URTNs and that it can be used to generate a new network that has a similar structure to the real network.