Customized bus network for efficient service: design of modular vehicle transfer scheme

This paper proposes a customized bus network design using modular vehicles and in-vehicle transfers. Four test scenarios (Modular-with-Transfer, Non-Modular-without-Transfer, Modular-without-Transfer, and Non-Modular-with-Transfer) are established. A mixed-integer nonlinear programming (MINLP) model with exclusive transfer constraints is formulated and a linearization strategy transforms it into tractable mixed-integer linear programming (MILP). Standard particle swarm optimization (PSO) is revised into a route-sequence-aware variant for better convergence on large networks. A synergy quantification framework quantifies combined benefits of modularity and transfers Validated on Sioux Fallsand Beijing transit data, the method cuts system cost by up to 20.82%, shortens travel distance by 26.89%–42.86% and lifts load factor by 8.24%–37.42%. For Beijing's real network, cost drops 1.21%–2.64%, load factor rises 22.72%–29.27%, andtravel time falls 0.2%–1.23%. Findings reveal route overlap dominates passenger choices, and coordinated expansion realizes synergistic load balancing.