Introduction
摘要
By the end of December 2020, a total of 45 cities in the Mainland of China had opened urban rail transportation systems, with an operating mileage of 7978.19 km, as shown in Fig. 1.1. Such large cities as Beijing, Shanghai, Guangzhou, Shenzhen, Nanjing, Wuhan, and Chengdu have basically realized “one-ticket transfer” operation in the “interconnection and interchange” urban rail networks. And another more 50 cities, according to the planning and construction arrangement, are constructing, or preparing for the construction of urban rail transit projects, the operation mileage of lines reaching up to nearly 8000 km in total.