For effective facilities planning: layout optimization then simulation, or vice versa?

It is widely accepted that simulation is an integral part of any effective facilities planning or layout study. Traditional approaches claim that layout optimization produces strategic results and therefore should precede simulation analysis, which focuses on operational issues. On the other hand, more recent studies suggest that running simulation models prior to conducting layout optimization produces more realistic layouts. In this paper, we contrast these two paradigms, with respect to the general assumptions and the types of applications that advocates from each paradigm have used to support their claim. In addition, we propose guidelines on which approach to pursue according to the layout study objectives and the characteristics of the system under consideration.