Different layouts result in different aisle widths.
As with anything, aisle widths can be a matter of preference. But in a distribution environment, you should always prefer aisle widths that maximize your storage space without leading to costly penalties in throughput capacity. If you tighten the aisles too much to fit in more racks, you’ll end up with slower loading and unloading and a loss in productivity. On the other hand, if you unnecessarily opt for wider aisles, you will pay a penalty on storage capacity.
Reach truck vendors suggest 9’-6” aisle widths. While that might be enough for equipment to operate, experience suggests that it will not be optimal. Aisles that are barely larger than 9’ will almost always complicate things for your labour. Care to see an example? Check out this video of a warehouse racking layout using 9’ aisles. As you will see, loading or unloading just one pallet turns out to be a pretty hard job for these stand-up forklift operators!
So, it may be true that 9’6’’ aisle widths are sufficient to operate, but I prefer 10’ as a minimum. A 10’ width provides the required space for labour to operate comfortably – particularly in lower height, slower paced buildings –, but it remains short of having a significant impact on storage capacity. In the case of a layout with double-deep racks, I may add a bit more space to the aisle width in order to accommodate the truck’s double reach mechanism. Similarly, in a faster-paced or greater height building, I will prefer wider aisles (11’ or more) to favour faster processing.