Incorporating heterogeneous distance metrics within block layout design

This paper focuses on optimal design of block layouts when using more than one distance metric within a single facility. Previous work in block layout has assumed a single distance metric, usually the shortest rectilinear distance between department centroids, during the design step. However, most facilities have more than one method of material handling and alternative material handling systems can imply alternative distance metrics and cost structures. Specifically, up to three distance metrics within a single facility are considered – the shortest rectilinear distance between centroids (appropriate for automated guided vehicles and fork-lift trucks), the Tchebychev (maximum) distance (appropriate for overhead cranes) and the shortest Euclidean distance between centroids (appropriate for conveyor lines). Optimal block layouts using each of these distance metrics individually and then collectively are compared and contrasted. This approach can also be used to compare layouts when the choice of material handling system is not clear. It is argued that incorporating the distance metric that best reflects the planned material handling device is more realistic than previous formulations, avoids block layouts that are sub-optimal for the material handling systems installed, and is quite workable within a heuristic optimization framework.