Integrated Optimization of Bus Bridging Route Design and Bus Resource Allocation in Response to Metro Service Disruptions

This paper focuses on the bus bridging service design in response to an unplanned metro line segment disruption. An integrated optimization model is constructed to address both bus bridging route layouts and bus resource allocation. Diversified routes, e.g., stop-by-stop route, express route, skip-stop route, parallel to the disrupted line segment are applied in the optimized bridging scheme to best respond to the passenger demands. An event-driven simulation-based genetic algorithm is designed to solve the optimization model. The simulation method is introduced to handle the uncertainty of passenger waiting time and the randomness of bus dwelling times at bridging stations and control the bus station capacities and guarantee the feasibility of the bridging schemes. Finally, the effectiveness of our proposed approaches is verified in a case study. Sensitivity analyses explore the impacts of fleet size and route diversity on the bridging performance. The results are instructive for transit agencies to operate bus bridging services. (C) 2022 American Society of Civil Engineers.