Third, existing studies in picker-to-parts orderpicking
systems mainly focus on random storage
assignments. Analytical models for optimising
dedicated and class-based storage assignment manual-
pick order-picking systems are still lacking. Furthermore,
storage assignment has an impact on the
performance of the routing method. However, this
effect seems to be largely neglected in the literature.
Instead, many authors focus on random storage
assignment to discuss about the performance of
routing methods.