Evaluating Chevron aisle design in unit load warehouses with multiple pickup and deposit points, Çok kapılı birim yük depolarda Chevron koridor tasarımının değerlendirilmesi

Abstract

In this study the effect of aisle design on the expected single-command travel distance from multiple P&D was investigated. We also present two different material flow policies that aims to determine the usage rate of the multiple P&D points located on the front of the warehouse. For the effect of aisle design we choose Chevron which is one of the most recently proposed non-traditional aisle designs by previous studies because it was shown to be very efficient for single-command operations from a single centrally-located P&D point. In order to investigate the performance of Chevron in terms of distance we compare it with an equivalent one-block traditional warehouse layout for three different warehouse shape ratios. Figure 1 shows the percentage improvement of Chevron in single-command tavel distance over an equivalent traditional design for central dense material flow policy. As seen in the figure whereas Chevron proposes more than 10% savings in travel for a single P&D point the saving decreases as the number of P&D points increases. Purpose: The purpose of this study is to investigate the effect of multiple P&D points on the performance of Chevron aisle design over a traditional one-block warehouse design in terms of expected travel distance under various warehouse sizes and different material flow policies. Theory and Methods: Single-command travel distance functions from equally-spaced multiple P&D points in both Chevron and the traditional design were developed under the assumptions of randomized storage and continuous storage space. We also used a discrete model of aisles and storage locations for more accurate distance calculations because continuous models do not consider the loss of storage capacity. Using these models we evaluate expected single-command distances in the respective layouts. Results: Our numerical analysis shows that Chevron design mostly performs better than an equivalent traditional aisle design under equal and central dense flow policies for three different warehouse shape ratios. However the proposed savings in travel distance by Chevron over the traditional design decreases as the number of P&D points increases. Additionally as the number of P&D points increases elongated warehouses (3/1) seem to be superior than deeper warehouses. When two proposed flow policies are compared we observed that central dense flow policy results in slightly better expected travel distances than equal flow policy. Conclusion: It was shown that Chevron still provides reduction on single-command distance for multiple P&D points compared to traditional designs. Especially when warehouses are elongated and material flows are dense around the center of the warehouse Chevron seems to perform better than traditional aisle designs. © 2019 Elsevier B.V. All rights reserved.