A concept closely related to the forward-reserve problem is dynamic storage. It aims at making the pick area
very small in order to reduce travel time, and bringing the SKUs to the storage locations dynamically, just in
time for the pick (by an automated crane, carousel, or VLM). The number of locations available in the
forward area is usually smaller than the total number of SKUs. As these systems are capable of achieving very
high picker productivity, they are becoming more and more popular (according to the authors’ knowledge at
least 15 implementations the last few years in Western Europe). The interesting decision problems are in the
interaction of the grouping of orders in a batch (more orders means fewer replenishments, but simultaneously
more SKUs are needed implying larger travel distances), the assignment of SKUs to locations, the timing of
the replenishments, and scheduling of the automated crane. This area is still virgin ground for academics.