A Last Mile Delivery Problem with Multitrip and Time Window Constraints in E-Logistics

Last mile delivery constitutes a major portion of e-logistics costs. In this study, we studied a last mile delivery problem to minimize the urban delivery costs of a company in the retail distribution sector under time window constraints and multi-trip distribution considerations. The company prioritizes customer satisfaction, so minimization of order delivery times is a secondary goal. For this purpose, we developed a mathematical model that will deliver the orders to the customer in the best delivery time window at the minimum cost. The study contributes to the literature as it is an original and a rarely studied subject. In order to solve the problem, we developed a Multifunctional Multi-trip Symmetric Closed Loop Vehicle Routing Problem with Time Windows. We developed and solved an integer programming model and compared the findings with the current situation in the company. Our findings show that our suggested model can provide approximately 32% cost advantage.