This study focuses on two-echelon synchronized logistics problems in the context of integrated water- and land-based transportation (IWLT) systems. The aim is to meet the increasing demand in city logistics as a result of the growth in transport activities, including parcel delivery, food delivery, and waste collection. We propose two models, a novel mixed integer linear joint model, and a logic-based Benders’ decomposition (LBBD) model, for a two-echelon problem under realistic settings such as multi-trips, time windows, and synchronization at the satellites with no storage and limited resource capacities. The objective is to optimize transfers and satellite assignments, thereby reducing overall logistics costs for street vehicles and vessels. Computational experiments demonstrate that the LBBD model is more robust in terms of solution quality and solution time on average while the added value of the LBBD is more evident when solving large-scale instances with 100 customers, reducing the overall costs by 10.6% on average and significantly reducing the fleet costs on both networks. Furthermore, we assess the effect of changing cost parameters and satellite locations in the proposed IWLT system–analyzing system behavior and suggesting potential improvements–and evaluate several system alternatives in city logistics–consisting of different transportation network designs (single- and two-echelon), vehicle types, and operational constraints. On average, the proposed two-echelon IWLT system reduces the number of kilometers traveled by vehicles at street level by ranging from 20% to 30% compared to a typical single-echelon service design that relies solely on trucks.

中文翻译：

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水基和陆基集成运输系统的两级多行程车辆路径问题，具有同步性


本研究侧重于水陆综合运输 （IWLT） 系统背景下的两级同步物流问题。其目的是满足由于运输活动（包括包裹递送、食品配送和废物收集）的增长而导致的城市物流日益增长的需求。我们提出了两种模型，一种是新颖的混合整数线性联合模型，另一种是基于逻辑的 Benders' decomposition （LBBD） 模型，用于现实设置下的两梯队问题，例如在没有存储和资源容量有限的卫星上的多次旅行、时间窗口和同步。目标是优化转运和卫星分配，从而降低有轨车辆和船只的总体物流成本。计算实验表明，LBBD 模型在解决方案质量和求解时间方面平均更稳健，而在解决具有 100 个客户的大规模实例时，LBBD 的附加值更为明显，总体成本平均降低 10.6%，并显著降低了两个网络的队列成本。此外，我们评估了在拟议的 IWLT 系统中更改成本参数和卫星位置的影响——分析系统行为并提出潜在的改进建议——并评估了城市物流中的几种系统替代方案——包括不同的运输网络设计（单梯队和两梯队）、车辆类型和运营限制。平均而言，与仅依赖卡车的典型单梯队服务设计相比，拟议的两梯队 IWLT 系统可将车辆在街道上的行驶公里数减少 20% 到 30%。