One fits all: a flexible branch-and-cut algorithm for picker routing in scattered storage warehouses
2026/01/15 by Constantin Wildt
New publication of the Chair for Management Science/Operations Research
Efficiently routing a picker in order to fulfill customer orders is one of the key operations that must be planned in a warehouse. In e-commerce, where vendors typically face a large volume of small and unpredictable orders to be picked from an extensive product range, items of the same stock-keeping unit (SKU) are stored in multiple storage locations rather than in a single dedicated position to account for this order structure. This storage assignment strategy, known as scattered storage, enables shorter picking tours in an online retail environment, as items of all SKUs are always located close to all other SKUs within the warehouse. Scattered storage is therefore widely adopted in the e-commerce sector. The underlying optimization problem, however, becomes harder as the storage positions to be visited must now be both selected and sequenced into a picking tour.
Driven by the rise of e-commerce, the so-called Single Picker Routing Problem with Scattered Storage (SPRP-SS) has recently gained substantial attention in both industry and academic research. Still, most solution procedures proposed assume a specific warehouse environment, such as a rectangular aisle configuration or a particular order structure, making them applicable to only a small subset of real-world problem settings.
In the chair's latest research paper, Felix Weidinger and Constantin Wildt present a flexible branch-and-cut algorithm that solves the SPRP-SS to proven optimality for arbitrary warehouse layouts and demand settings. Further key contributions of the paper are:
• An extension of the procedure to decentralized depot systems and asymmetric distance matrices, making the approach even more flexible, and
• A set of SPRP-SS instances featuring a non-rectangular warehouse layout to stimulate further research in this field.
In several computational tests, we were able to show that our solution approach is overall superior in solving the SPRP-SS compared to standard solver Gurobi regarding solution time and quality. Our findings therefore contribute to the planning of order fulfillment in numerous real-world scenarios that do not correspond to standard assumptions.
The article is available as open access in OR Spectrum:
Wildt, C., Weidinger, F. One fits all: a flexible branch-and-cut algorithm for picker routing in scattered storage warehouses. OR Spectrum (2026).
