This VNA storage setup guides the manually controlled MHE along rails to efficiently improve its movement accuracy along the VNA. This results in the MHE being able to carry larger loads at greater speed without the risk of colliding with the racking. However, with the constant banking into the rails, over time the MHE may sustain physical damage.
Nowadays, however, wire guidance is the conventional method for automated movement down VNA, due to its easier maintenance and quality control.
The rail guidance system must be incorporated into part of the design, as the rails may impose lateral loads on the slab and the base of the racking.