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Warehouse Layout and Pick Sequence

 |  added by Gwynne Richards


As soon as you enter the majority of warehouses you are faced with row upon row of storage racks. The most interesting aspect from a consultancy viewpoint is how each row of racking is identified. The following is a suggestion as to how to identify rows of racking or shelving within a warehouse facility.

If a company is looking to introduce greater efficiency into its picking operation and reduce travel time it needs to consider carefully how it identifies its pick locations.

How to do it

In Figure 1 below we see that each row of racking is given a number, 01, 02 etc. This results in one-sided picking as denoted by the arrows. The numbers denoted in the pick locations are the pick sequence. The shaded area is a pick location for a particular order.

In this example the first pick location will have a location identification (ID) of 01 (row) 06 (bay) 01 (ground floor) – 010601 whilst the second location will be 020301. The pick list produced for the operator will automatically send him/her to location 01 first.This can result in large walking distances as the order picker first visits the location on one side of the aisle and then returns to visit the locations on the other side. This method of identification can be utilised in very wide aisles however for narrow aisle racking and shelving it is more efficient to number the aisles as can be seen in Figure 2.

Figure 1 – Rack numbering

Figure 1 – Rack numbering

In Figure 2 the aisles are numbered as opposed to each row which results in the picker traversing the aisle and thus picking from both sides at one pass. This will reduce the amount of travel significantly.


In the example in Figure 2 the first pick location is 010601 and the second pick location becomes 011101.

The ideal scenario would be for the Warehouse Management System (WMS) to fully optimise the pick sequence however very few WMS are able to do this. In fact an experienced operator with a paper based system is more likely to do this independently (see figure 3) as technology prompts the picker to pick in numerical sequence.

Figure 3

This is just one tool a warehouse manager can use to improve the efficiency of the warehouse by reducing the amount of travel undertaken. In many warehouses travel can account to up to 50% of the picking time.

Another tool to assist warehouse managers to improve warehouse space efficiency is the construction of a mezzanine floor. In many warehouses space is a limiting factor however few companies utilise the redundant space above the warehouse doors. Providing the warehouse is sufficiently high enough (circa 6 metres+) it is possible to construct a second floor which can accommodate further storage or can be utilised as an area for undertaking value adding services.

As the mezzanine floor is above the despatch doors a chute can be introduced to transfer the products down to the despatch area once picked and/or packed and labelled.

The introduction of shuttle technology has enabled some companies to hold pallets above the dock doors which can either be for short or long term storage or can be sequenced for despatch rather than using much needed floor space as can be seen in Figure 4 below.

Figure 4 Storage above the dock doors

Figure 4. Storage above the dock doors. Photograph courtesy of Toyota Forklifts

Adapted from Van den Berg JP (2007) Highly Competitive Warehouse Management, Management Outlook Publishing Buren

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