Joint Timetabling and Vehicle Formation Design for Autonomous Modular Buses Under Two-Level Route Layout Mode

This paper proposes a novel two-level route layout mode for the autonomous modular bus (AMB) based urban public transportation corridor. The two-level route consists of two components: mainline and feeder routes. The mainline covers all stations along the corridor, while feeder routes serve only specific consecutive stations. The departure and terminal stations of the feeder route are set up as special stations where AMBs can combine and split. The feeder route layout scheme remains fixed during an operating period but can be adjusted across different periods. We establish a mixed-integer programming model to concurrently determine the optimal special station deployment scheme, AMB timetable, and vehicle formation plan under the two-level route layout mode. The objectives are to minimize the average passenger waiting time, AMB energy consumption, and the number of special stations. Subsequently, the model is addressed by employing the multi-objective boxing match algorithm. A case study is conducted utilizing a real-world urban transportation corridor, comparing the proposed method against an optimization approach that concentrates on AMB timetabling and vehicle formation planning without considering feeder routes. The results underscore the superiority of our method, which reduces average passenger waiting time by 13.00% and vehicle energy consumption by 2.53%, without increasing the number of required special stations.