How to determine slot sizes in a unit-load warehouse

Abstract

Storage racks in a unit-load warehouse typically have slots of equal height, whereas the unit-loads themselves have heights that vary significantly. The result of this mismatch is unused vertical space and storage areas larger than they otherwise could be. We propose the use of storage racks with multiple slot heights to better match the distribution of pallet heights. The slot profile design problem seeks the best set of slot heights and their corresponding quantities such that a desired service level is met, where service level is the probability that all pallets present in a period can be stored. Using data from several companies, we found that the potential space savings of using multiple slot heights are between 29% and 45%.