A model for determining the number of storage blocks and block lengths in a rectangular warehouse

Official URL: http://risc01.sabanciuniv.edu/record=b1081774 (Table of Contents)

This thesis study focuses on the savings that can be attained by adding unequally spaced cross aisles in a rectangular warehouse and the best locations of these cross aisles. Earlier research suggests that adding cross aisles perpendicular to main aisles can bring significant savings with respect to order picking travel distance. In the related literature cross aisles are distributed between storage blocks that are equal in length. In this thesis, the locations of cross aisles will be investigated in detail and evaluated in terms of travel distance and storage space. Storage block lengths between cross aisles are allowed to be different in length. Based on our experiment results, these unequally spaced cross aisle configurations enable more saving on order picking travel distance than equally spaced cross aisles. We have also investigated the issue of possible space savings by using less number of unequally spaced cross aisles compared to equally spaced cross aisles. Our research suggests the same travel distance saving due to equally spaced cross aisles can be achieved with less number of cross aisles (less number of storage blocks) distributed between block lengths (cross aisle spacing) that are unequal in length. Additionally, an interesting pattern in terms of the lengths of storage blocks between unequally spaced cross aisles is observed. In the configuration of storage blocks that provide maximum travel distance saving, the length of the block in the middle gets wider as order size increases. This pattern is observed for all of the warehouse types investigated in this thesis. Since warehouse design is a strategic problem concerning long-term investment, the results provided within this thesis provide insights in order to decrease the investment costs or increase the efficiency of warehouse operations.