Integrated physical and service network design of suburban rail under the coordination of urban rail

Motivated by a released official policy in China to promote the development of suburban rail within metropolitan areas, this paper investigates the suburban rail network design problem by integrating the physical network and the service network design, while considering a higher level of passenger satisfaction by assigning passengers to trains rather than to service routes widely adopted in previous works. The physical network design problem lies in determining the location of the suburban stations and suburban section tracks to be newly constructed, by considering the coordination of the existing urban rail network. The service network design problem aims to decide the newly operated service routes and the corresponding frequency and timetable of vehicles running on these service routes. We formulate the studied problem as a mixed integer linear programming (MILP) model, which minimises the weighted sum of the construction cost, operation costs, and generalised cost of passengers. Many practical requirements are considered to ensure the attractiveness of the computed solutions. A variable neighbourhood search-based (VNS-based) heuristic is designed to efficiently solve instances with different scales, including hypothetical instances and a practical-size real-world instance generated based on the Chongqing metropolitan in China.