Minimizing work-in-process and material handling in the facilities layout problem

We consider the plant layout problem for a job shop environment. This problem is generally treated as the quadratic assignment problem with the objective of minimizing material handling costs. Here we investigate the relationship between material handling costs and average work-in-process. Under restrictive assumptions, an open queueing network model can be used to show that the problem of minimizing work-in-process reduces to the quadratic assignment problem. In this paper, we generalize these results through a simulation model, and develop a simple secondary measure which allows us to select the layout that minimizes average work-in-process levels from among solutions that are similar with respect to the objective function for the quadratic assignment problem.