Train Planning on a Single Track Shared-Use Passenger and Freight Corridor With Demand Considerations

While the train scheduling problem has been investigated for an extended period of time, shared passenger and freight corridor planning and capacity analysis have gained growing attention recently, due largely to the emergence of higher speed rail lines in the US. This study proposes an integrated, hypergraph-based approach that considers constraints from infrastructure supply as well as passenger demand in solving the train scheduling problem on a passenger-freight shared rail corridor. Two approaches are proposed to capture different policies which could be implemented in real world. The first, sequential approach considers passenger train priority in schedule planning, and then develop freight trains schedules given the fixed schedule of passenger trains. In the second approach, we minimize the total costs of freight and passenger trains simultaneously. Our results indicates that the marginal cost increase for freight railroad due to considering passenger train priority is larger than the associated marginal cost reduction for passengers. We also find that using high resolution time units in the mathematical formulation does not significantly improve the solution, meanwhile causing substantial increase in computation time. Therefore we suggest choosing coarser a time unit to first generate an approximate solution, which is subsequently used to reduce the search space for feasible train schedules using a finer-grained time unit. We show that this considerably saves computational effort.