In the correlated storage assignment problem, products are assigned to
storage/pick zones in a warehouse to minimize picking effort. Unlike
previous work which has focused on minimizing travel distance, our
objective is to minimize the number of zones that must be visited to fill
the orders. This problem is NP-Complete so heuristic methods are developed
to find solutions. We present a Lagrangian relaxation approach as well as
several other construction heuristics. Improvement methods discussed
include 2-exchanges and cyclic exchanges. We also consider problem
variations such as different product sizes, stock splitting, and
rewarehousing. Computational results are presented for problems containing
up to 10664 products and 40 zones. In particular, our results show that
cyclic exchanges are very powerful and can be used to obtain solutions 15%
better than those from using popularity, a standard approach.