Design of Plant Layouts with Queueing Effects

In this paper, we present a formulation of the plant layout problem where the objective is to minimize work-in-process. We show that the choice of layout has a direct impact on work-inprocess accumulation, manufacturing lead time, achievable throughput rates, and required material handling capacity. More importantly, we show that layouts generated using a queueing-based model can be very different from those obtained using conventional layout procedures. In particular, we present a number of surprising and counter-intuitive results. For example, we show that reducing overall distances between departments can increase average work-in-process in the plant. We also show that the relative desirability of a layout can be affected by non-material handling parameters, such as department utilization levels, variability in processing times at departments and variability in product demands.