Analysis and optimal design of discrete order picking technologies along a line

Order picking accounts for most of the operating expense of a typical distribution center, and thus is often considered the most critical function of a supply chain. In discrete order picking a single worker walks to pick all the items necessary to fulfill a single customer order. Discrete order picking is common not only because of its simplicity and reliability, but also because of its ability to pick orders quickly upon receipt, and thus is commonly used by e-commerce operations. There are two primary ways to reduce the cost (walking distance required) of the order picking system. First is through the use of technology‐conveyor systems and/or the ability to transmit order information to pickers via mobile units. Second is through the design‐where best to locate depots (where workers receive pick lists and deposit completed orders) and how best to lay out the product. We build a stochastic model to compare three configurations of different technology requirements: single-depot, dual-depot, and no-depot. For each configuration we explore the optimal design.