The studied warehouse section consists of three parts: two of them have 12 front piles each and the
third part has 6 front piles (Figure 1). The piles are 7m high and the products are stored in up to 4 depths
of pile levels. The main aisle is used by the clarks to gain access to the front piles. The aisle is wide
enough to allow the clarks to remove the items of the front piles and to retrieve items stored in the deeper
levels. Each part of the section contains different groups of products.