  Autonomous mobile robots (AMRs) are increasingly used to automate operations
in intralogistics. One crucial feature of AMRs is their availability, allowing
them to operate 24/7. This work addresses the multibay unit load
pre-marshalling problem, which extends pre-marshalling from a single bay to
larger warehouse configurations with multiple bays. Pre-marshalling leverages
off-peak time intervals to sort a block stacking warehouse in anticipation of
future orders. These larger warehouse configurations require not only the
minimization of the number of moves but also the consideration of distance or
time when making sorting decisions. Our proposed solution for the multibay unit
load pre-marshalling problem is based on our two-step approach that first
determines the access direction for each stack and then finds a sequence of
moves to sort the warehouse. In addition to adapting the existing approach that
integrates a network flow model and an extended A* algorithm, we additionally
present an exact constraint programming approach for the second stage of the
problem-solving process. The results demonstrate that the presented solution
approach effectively enhances the access time of unit loads and reduces the
sorting effort for block stacking warehouses with multiple bays.
