Design of diagonal cross-aisle warehouses with class-based storage assignment strategy

Non-traditional warehouses shorten the travelled paths to store and retrieve (S/R) the loads, thanks to additional aisles crossing the parallel racks. This paper provides the analytic model to best design a non-traditional warehouse for unit-load (UL) with diagonal cross-aisles and storage policy according to the class-based storage (CBS) strategy. The model minimizes the average single-command cycle time to S/R the loads, best sizing the classes, their shape, and the position/numbers of additional aisles. The focus is on both 2- and 3-CBS optimizing the number of diagonal cross-aisles to best balance the travel time reduction and the loss of storage space due to the aisles. Furthermore, benchmarking toward standard warehouses with no diagonal cross-aisles and random assignment strategy allows quantifying the positive impact of the proposed design configuration on the daily warehouse operations.