Invited Review Design and control of warehouse order picking: A literature review Rene ´ de Koster * , Tho Le-Duc, Kees Jan Roodbergen RSM Erasmus University, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands Received 29 August 2005; accepted 17 July 2006 Available online 25 October 2006 Abstract Order picking has long been identified as the most labour-intensive and costly activity for almost every warehouse; the cost of order picking is estimated to be as much as 55% of the total warehouse operating expense. Any underperformance in order picking can lead to unsatisfactory service and high operational cost for the warehouse, and consequently for the whole supply chain. In order to operate efficiently, the order-picking process needs to be robustly designed and optimally controlled. This paper gives a literature overview on typical decision problems in design and control of manual order-pick- ing processes. We focus on optimal (internal) layout design, storage assignment methods, routing methods, order batching and zoning. The research in this area has grown rapidly recently. Still, combinations of the above areas have hardly been explored. Order-picking system developments in practice lead to promising new research directions. Ó 2006 Elsevier B.V. All rights reserved. Keywords: Order picking; Warehouse management; Logistics 1. Introduction As more companies look to cut costs and improve productivity within their warehouses and distribution centres, picking has come under increased scrutiny. Order picking – the process of retrieving products from storage (or buffer areas) in response to a specific customer request – is the most labour-intensive operation in warehouses with man- ual systems, and a very capital-intensive operation in warehouses with automated systems (Goe- tschalckx and Ashayeri, 1989; Drury, 1988; Tomp- kins et al., 2003). For these reasons, warehousing professionals consider order picking as the highest- priority area for productivity improvements. Several recent trends both in manufacturing and distribution have made the order-picking design and management become more important and complex. In manufacturing, there is a move to smaller lot- sizes, point-of-use delivery, order and product customisation, and cycle time reductions. In distri- bution logistics, in order to serve customers, compa- nies tend to accept late orders while providing rapid and timely delivery within tight time windows (thus the time available for order picking becomes shorter). Many smaller warehouses are being replaced by fewer large warehouses to realise econ- omies of scale. In these large warehouses, the daily 0377-2217/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.ejor.2006.07.009 * Corresponding author. Tel.: +31 10 4081719; fax: +31 10 4089014. E-mail address: rkoster@rsm.nl (R. de Koster). European Journal of Operational Research 182 (2007) 481–501 www.elsevier.com/locate/ejor