An improved adaptive large neighborhood search algorithm on collaborative last mile delivery with roaming customers

This paper addresses the challenge of rising operational costs in last-mile delivery caused by end-customer no-shows. The study proposes a collaborative operational framework for last-mile delivery that accommodates roaming customers, enabling them to be serviced by multiple depots as they transition between different locations. A mixed-integer programming (MIP) model is formulated to minimize the operational costs of last-mile delivery under the proposed framework. To improve the model’s practicality and computational efficiency, an adaptive large neighborhood search (ALNS) algorithm is developed, incorporating tailored neighborhood structures. Furthermore, a late acceptance strategy is embedded within the algorithm to mitigate the risk of premature convergence to local optima. The experimental results demonstrate that, in the absence of depot collaboration, the multi-depot model achieves a 16.9% reduction in operational costs compared to the single-depot model. Moreover, when depot collaboration is enabled, the average cost reduction percentage significantly increases to 40.37%. Notably, under the multi-depot collaborative framework, considering customers' roaming behavior—as opposed to fixed single-location assumptions—leads to a substantial 54.6% reduction in operational costs.