Parcel logistics services play a vital and growing role in economies worldwide, with customers demanding faster delivery of nearly everything to their homes. To move larger volumes more cost effectively, express carriers use sort technologies to consolidate parcels that share similar geographic and service characteristics for reduced per-unit handling and transportation costs. This paper focuses on an operational planning problem that arises in two-stage sort systems operating within parcel transportation networks. In this context, primary sorters perform an initial grouping of parcels into “piles” that are subsequently dispatched when necessary to secondary sorters; there, each pile’s parcels are fine-sorted based on their final destinations and service class for packing into outbound transportation vehicles. Such systems must be designed to handle a high degree of uncertainty in the quantity and timing of arriving parcels, yet must also group and sort the parcels to meet tight departure deadlines. Thus motivated, this paper presents robust planning models that assign parcels to sort equipment while protecting against different sources of demand uncertainty commonly faced by parcel carriers. We demonstrate the computational viability of the proposed models using realistic-sized instances based on industry data, and show their value in providing sort plan alternatives that trade off operational costs and levels of robustness.

包裹物流服务在全球经济中发挥着至关重要且不断增长的作用，客户要求更快地将几乎所有物品送达家中。为了以更具成本效益的方式运送更大的货物，快递承运商使用分拣技术来合并具有相似地理和服务特征的包裹，以降低单位处理和运输成本。本文重点研究在包裹运输网络中运行的两阶段分拣系统中出现的运营规划问题。在这种情况下，初级分拣机将包裹初步分组为“一堆”，随后在必要时分派给二级分拣机；在那里，每一堆包裹都根据最终目的地和服务等级进行精细分拣，以便装入出境运输车辆。此类系统的设计必须能够处理包裹到达数量和时间的高度不确定性，还必须对包裹进行分组和分类以满足紧迫的出发期限。因此，本文提出了稳健的规划模型，将包裹分配给分拣设备，同时防止包裹承运人通常面临的不同需求不确定性来源。我们使用基于行业数据的真实大小的实例展示了所提出模型的计算可行性，并展示了它们在提供排序计划替代方案方面的价值，这些替代方案可以权衡运营成本和稳健性水平。本文介绍了稳健的规划模型，可将包裹分配给分拣设备，同时防止包裹承运人通常面临的不同需求不确定性来源。我们使用基于行业数据的真实大小的实例展示了所提出模型的计算可行性，并展示了它们在提供排序计划替代方案方面的价值，这些替代方案可以权衡运营成本和稳健性水平。本文介绍了稳健的规划模型，可将包裹分配给分拣设备，同时防止包裹承运人通常面临的不同需求不确定性来源。我们使用基于行业数据的真实大小的实例展示了所提出模型的计算可行性，并展示了它们在提供排序计划替代方案方面的价值，这些替代方案可以权衡运营成本和稳健性水平。