lot of definitions of various layout problems: one of the first dates back to 1957, when it was defined as an ordinary industrial problem with the aim of minimizing the cost of transporting materials between the different workstations [3] [4]. Transportation, as a matter of fact,
is the key factor in the facility layout problem. A well‐known study of the 1970s [5], in fact, has highlighted that from 20% to 50% of total operating manufacturing costs are related to the material handling activities and that these costs could be reduced by 10% to 30% annually with efficient facility planning. In addition to the direct target of minimizing material handling costs, effective facility layout planning also has indirect advantages: for example, it can help to decrease the work in process (WIP) and the throughput times (TT) [6], or it can simply facilitate the control of information and material flows [7