Typically, the travel and return times account for over half of the total OP time (Tompkins, 1998), and
most of the research work in increasing the efficiency of OP has focussed on the assumption. This does
not apply to the problem considered here, where the retrieval times are considerably higher due to the
nature of the products. Supported by the results of Stage 1, the retrieval times can be reduced by
rearranging the warehouse and applying storage principles as discussed in Section 2.