Integrated Optimization of Vehicle Scheduling and Passenger Assignment of Demand-Responsive Transit and Conventional Buses under Urban Rail Transit Disruptions

Urban rail transit systems are vital to urban mobility, yet disruptions may cause significant congestion or delays for passengers. Traditional evacuation strategies, predominantly reliant on conventional buses, could not consider the diverse characteristics of passengers. This study proposes an optimization method that integrates the services of demand responsive transit (DRT) and conventional buses to efficiently and passenger-friendly evacuate stranded passengers when urban rail transit disruption occurs. An integer linear programming model is proposed to deliver both a vehicle schedule (including the number of used DRT vehicles and conventional buses, as well as the routes of the vehicles) and a passenger assignment solution simultaneously. The route of the DRT vehicle is considered variable, and passenger assignment with each vehicle depends on the passengers’ destination and the route of the assigned vehicle. Moreover, we propose a preprocessing method to generate a set of feasible routes for each vehicle. We consider two objectives: maximize the number of transported passengers and minimize the travel time. An epsilon-constraint-based algorithm is used to find the Pareto optimal solutions for the proposed bi-objective model. The case study is conducted using data from a real-world urban public transportation network in China to evaluate the effectiveness of the proposed method. The experimental results show that the integrated optimization approach achieves a significant average reduction of 73.88% in travel time and 72.39% in the total number of vehicles used compared with single-mode evacuation strategies utilizing only conventional bus services. Furthermore, the experimental results obtained by integrated optimization of the vehicle route scheduling and passenger assignment achieve up to 80.93% reduction of travel time and 11.14% increase of transported passengers, compared with the solutions by fixed vehicle routes.