Schedule Coordination Design in a Trunk-feeder Transit Corridor with Spatially Heterogeneous Demand

As a widely present form of bimodal transit systems, the trunk-feeder transit corridor has received less attention in the academic research compared to the conventional single-modal systems, partly due to the difficulty in the two-dimensional modeling. The schedule coordination of this corridor has been largely ignored, which can potentially strengthen the mutually reinforcing relationship between the trunk transit (e.g., rail) and the feeder transit (e.g., bus). In light of this, the paper proposes a novel two-stage programming model with the objective of minimizing the total cost to design a coordinated trunk-feeder corridor. In stage one, the continuous approximation approach and the discrete method are incorporated to obtain an optimized uncoordinated scheme and a feasible layout. The screened layout parameters such as the specific station location, feeder line location, length of the feeder line segments parallel to the trunk line, and the passenger flow distribution, are recruited into the coordination design in stage two. A nested two-phase optimization algorithm integrated with the analytic method and adaptive genetic algorithm is proposed to find the solutions to the mixed integer nonlinear program issue. Results show that the proposed method is suitable for heterogeneous schedule coordination design and the coordination strategy is more preferable at a lower-level heterogeneous demand. Meanwhile, different from the conventional approaches, this method can generate a rational cost-saving coordination scheme with a feasible layout under the two-dimensional heterogeneous demand pattern.