Operational planning of integrated urban freight logistics combining passenger and freight flows through mathematical programming

Recently, more environmentally friendly urban logistics (UL) services have emerged based on the integration of freight deliveries into passenger bus networks to perform UL activities within cities. The aim is to reduce the number of combustion powered vehicles operating within cities, thus improving the city quality of life in terms of pollution, noise, traffic congestion etc. This paper addresses the operational planning of an UL service where freight is dropped by clients at bus hubs located outside the city center, transported by buses to one of their stops located in the city center, and delivered to the destination address by a last mile operator (LMO). To support the operational planning of the service covering the entire logistics process (from the reception of freight delivery requests until the delivery of the requests on their destination), five operational objectives are considered and, for each objective, an Integer Linear Programming (ILP) model is proposed. The objectives cover the perspectives of the bus network operator and of the LMO and some objectives address the robustness of the operational planning solutions to failures. Additionally, five operational planning cases of practical interest where two of the previous objectives are lexicographically optimized are also addressed including a description of how they are solved with the proposed ILP models. We demonstrate the merits of the different operational planning methods with different generated instances whose characteristics allow the assessment of the impact of different parameters on the results obtained by the proposed models when solved with a standard solver.

近年来，依托将货运配送融入公交网络的模式开展城市内物流作业的环保型城市物流（Urban Logistics, UL）服务应运而生。该类服务旨在减少城市内燃油动力车辆的运行数量，进而从污染、噪声、交通拥堵等维度改善城市人居生活质量。本文针对一类城市物流服务的运营规划问题展开研究：客户将货运货物寄放在市中心外的公交枢纽，由公交车辆运至市中心内的公交站点，再由最后一公里运营商（Last Mile Operator, LMO）配送到最终收货地址。为支撑覆盖全物流流程（从接收货运配送请求直至将货物送达目标地址）的该类服务运营规划，本文设定五项运营目标，并针对每项目标提出相应的整数线性规划（Integer Linear Programming, ILP）模型。这些目标兼顾了公交网络运营商与最后一公里运营商的运营视角，其中部分目标还针对运营规划方案在突发故障下的鲁棒性进行考量。此外，本文还研究了五项具有实际应用价值的运营规划场景——即对前述两项目标以字典序优化的场景，并详细说明了如何利用所提出的整数线性规划模型求解这些场景。本文通过多组随机生成的测试算例验证了不同运营规划方法的优劣；这些测试算例的参数特征可用于评估不同参数对所提模型在使用标准求解器求解时所得结果的影响。