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.