Optimizing Fishbone Aisles for Dual-Command Operations in a Warehouse

Unit-load warehouses store and retrieve unit-loads, typically pallets. When storage and retrieval operations are not coordinated, travel is from a pickup and deposit (P&D) point to a pallet location and back again. In some facilities, workers interleave storage and retrieval operations to form a dual-command cycle. Two new aisle designs proposed by Gue and Meller (2006) use diagonal aisles to reduce the travel distance to a single pallet location by approximately 10 and 20 percent for the two designs, respectively. We develop analytical expressions for travel between pallet locations for one of these — the fishbone design. We then compare fishbone warehouses that have been optimized for dual-command to traditional warehouses that have been optimized in the same manner, and show that an optimal fishbone design reduces dual-command travel by 10–15 percent.