EXPLOITING THE TIMETABLING FLEXIBILITY IN THE CONTEXT OF THE VEHICLE SCHEDULING PROBLEM WITH HETEROGENEOUS FLEET

ABSTRACT In the context of a heterogeneous fleet, the single-depot Vehicle Scheduling Problem is known as the Vehicle Type Scheduling Problem (VTSP). In this paper, we extend a VTSP model proposed in the literature to enable timetabling flexibility. Two strategies were developed to promote flexibility: aggregated trips and time windows. The former allows to aggregate two or more trips, occurring close in time, into a single one through the use of larger vehicle types, while the latter allows shifting the departure time of scheduled trips backward in few minutes. Both approaches were tested on generated instances that simulate the traffic behavior of a Brazilian city, where clock-face departure pattern is not required and demand peak times occur. We verified significant savings in the daily operation of the public transportation service with acceptable impact on passengers’ experience.

摘要：在异构车队场景下，单场站车辆调度问题被称为车辆类型调度问题（Vehicle Type Scheduling Problem，VTSP）。本文拓展了现有文献中提出的VTSP模型，以实现时刻表编排灵活性。为提升灵活性，本文提出两种策略：行程聚合（aggregated trips）与时间窗（time windows）。前者允许通过使用更大尺寸的车辆类型，将时间上紧密相邻的两次及以上行程整合为单一行程；后者则可将已排定行程的发车时间向后微调数分钟。上述两种方法均在模拟巴西城市交通运行特征的生成测试实例上开展了测试，这类城市无需采用整点发车模式，且存在出行需求高峰时段。研究证实，该方案可在对乘客出行体验造成可接受影响的前提下，显著节约公共交通服务的日常运营成本。