Analysis of the length of order-picking paths determined using the S–shape method

Background: Order-picking is a fundamental warehousing activity that accounts for in excess of 60% of total warehousing costs. Movements of pickers consume as much as half of the picking time. Thus determining picking paths is crucial. The most frequently used method is the S-shape one. and methods: The average picking path length for 240 variants of the storage area (depot location, storage strategy), inventory (ABC-storage class sizes, probability of retrieving) and customer order (number of lines 5, 10, 15) parameters was calculated. 100 simulations were carried out each time. MS Excel spreadsheet, along with macros (VBA) were used.: The comparison were made of path lengths for a single block warehouse with 320 storage locations, Within-Aisle/Random storage strategies and low-level picking. Depot locations in the corner of a warehouse and in the middle of a front aisle were considered. The path lengths significantly varied with the variants that were analyzed. The shortest paths were observed for the Within-Aisle strategy, corner located depot, order sizes 5 or 10 and sizes of ABC-storage classes equal to 5/35/60% or 10/35/55% of all 320 storage locations under a retrieving probability of 90/5/5%.: Better and worse picking variants exist, influencing significantly the length of picking paths determined using the S-shape method. In general, the depot location is less important, even though the best variant assumed a corner location, while a location in the middle of a front aisle gives shorter paths on average. A much more important factor is the storage strategy. Lack of the strategy (randomness) substantially extends path lengths (by 50% on average).