Key Issues in Rail Transit Four-network Integration Planning

［Objective］Advancing urban rail transit four networks (mainline railways, intercity railways, suburban railways, and urban rail transit) integration is an urgent need for China to promote new urbanization with metropolitan areas as the main spatial carrier. Therefore, it is necessary to study the key issues in planning for the integration of four networks. ［Method］Based on the technological and economic attributes of urban rail transit and the core objectives of network integration, the concept of four-network integration planning is proposed. The scope of the integration planning is defined from the dimension of urban rail transit on the basis of a systematic metropolitan area scope sorting. The primary forms of four-network integration are clarified according to the functional means and passenger flow characteristics of various levels of urban rail transit. The basic methods and technical points for four-network integration are presented at three levels: network, line, and node, with practical case studies. ［Result & Conclusion］The planning for the four-network integration is a scientifically sound implementation arrangement aligned with the stages of urban and transport development. The scope of four-network integration planning typically covers contiguous developed areas within metropolitan regions, with core areas of mutual connectivity and permeability generally within a 30 to 40 km radius spatial coverage from metropolitan area central city. The main forms of four-network integration are complementary integration and compensatory integration. Regarding the integration techniques, the network levels focus on functionalities, the line levels emphasize corridors, and the node levels target hubs.