Layout method of the connecting lines in the network planning of urban mass transit

The connecting line is an important establishment in the railway network of urban mass transit. The mathematical model is built based on the connection diagram through analyzing the quantity relation of the connecting lines in rail traffic network. According to the characteristics of urban mass transit-high construction cost and difficulty of changing civil engineering for already-built line, taking long-term network development into consideration, two kinds of layout methods for connecting line are put forward, namely, increasing the length method for main passage and optimization method for construction cost. Increasing the length method for main passage is in accord with the thoughtway of 'in proper sequence'. The layout of connecting lines will be established gradually along with the steps and sequences of network development. This method is applicable to such network of existing urban mass transit system with fixed pattern, inconvenient reconstruction, less lines and simpler connection relation between lines. The optimization method for construction cost, which is originated from the thoughtway-considering the overall situation and general plan, is adopted to establish the layout of connecting lines. This method is applicable to such network at the beginning of urban mass transit network planning with more lines and more complicated connection relation between lines. The practicability and the scientificalness of the method are validated through actual application of special plan in Beijing urban mass transit network.