Integrating logistics operations for sustainable last-mile deliveries with a consolidation-based assignment heuristic

The City Line project aims to promote collaboration between logistics operators and to ensure low emissions for last-mile deliveries in cities. This collaboration involves sharing existing assets and capacities, logistics facilities, and services with competitors to save costs, improve global transport efficiency, and extend one's service zone; it is based on negotiating framework contracts with transport providers, occurring before collaboration.
An algorithm uses a depth-first search strategy for each commodity, starting from a set of services to pick up the delivery request at its origin and within the pickup time window and continuing by appending services to drop off at the destination location within the drop-off time window. The search terminates when no more services are to be appended or when the maximum number of intermediate stops is reached; it results in a set of feasible paths, each a sequence of services. Then, for each period within the rolling horizon, the algorithm selects the path with the minimum score, depending on cost and environmental impacts, and assigns the delivery request to this path, updating the capacities of the services in the path, accordingly. Delivery requests for subsequent periods within the rolling horizon are assigned to the used paths accommodating the new request with the least additional capacity requirement using the BestFit algorithm.
The potential impacts of collaboration and low-emission zones are analyzed in Belgium through four scenarios. Six types of vehicles, each with its characteristics and emissions, are included, and costs are computed considering the weight and volume of parcels. The results show that increased collaboration among logistics service providers leads to higher loading rates, greater acceptance of delivery requests, and more diverse use of vehicles, significantly reducing CO2 and NOX emissions. These findings offer promising implications for adopting collaborative transport and sustainable logistics, contributing to developing the Physical Internet concept. The study's results could also provide valuable insights for policymakers in developing decision-support tools to promote sustainable logistics practices.