The pq-median problem seeks to locate hierarchical facilities so as to obtain a coherent structure. Coherence requires that the entire area assigned to a facility at one level must be assigned to one and the same facility at the next higher level of the hierarchy. Although optimal solutions to the pq-median problem have been obtained by a combination of linear programming and branch-and-bound, large problems are likely to require heuristic approaches for the foreseeable future. This paper proposes several efficient heuristic methods whose solution properties appear to be quite good when compared to those of exact procedures.
