A comparison of picking, storage, and routing policies in manual order picking

This article examines the effect of three process decisions (picking, storage, and routing) on order picker travel, which is a major cost component of order fulfillment. The authors use a simulation model based on the operations of a distribution center that is currently picking one order at a time, storing product in a haphazard or random fashion, and using a simplistic procedure for routing pickers. Several picking, storage, and routing policies are evaluated to determine which process decision provides the greatest percent savings relative to the current baseline policies. Several sensitivity analyses are completed to examine the effect of order size, warehouse shape, location of pick-up/drop-off point, and demand distribution on performance. Results show that batching of orders yield the greatest savings particularly when smaller order sizes are common. Results also show the use of either a class-based or volume-based storage policy provides nearly the same level of savings as batching, while being less sensitive to the average order size. r 2003 Elsevier B.V. All rights reserved.