Class-based storage warehouse design with diagonal cross-aisle

Background: Unit-load (UL) warehouses are among the most diffuse solutions to store items stocked in pallets, while class-based storage (CBS) assignment is an effective strategy balancing the storage space need and the UL traceability. This paper proposes a design strategy to reduce the access time for UL-CBS systems based on the inclusion of one additional diagonal aisle crossing the racks and the parallel aisles accessing the storage bays. Methods: The introduced design strategy is based on the analytic models to compute the access time for one diagonal-cross aisle warehouses with 2- and 3-CBS system. The minimization of the closed form expressions getting the average time to reach the storage bays allow reducing the travelled paths to store and retrieve (S&R) the ULs. Results: Comparison of the average time to S&R the ULs between traditional warehouses and the proposed configuration highlights the positive impact of the diagonal cross-aisle inclusion. In addition, a case example for a company operating within the food sector shows performance increase of about 33% respect to the correspondent traditional warehouse configuration. Conclusion: The interest in non-traditional warehousing systems rises because of the savings in the time to S&R the ULs. Analytic and even more general models to compute such savings are of help to best design the storage area increasing the inbound handling performances.