VNA racking may be set out in much narrower aisles than those required by reach truck operations. High-rack stacker trucks, equipped with rotating or sliding pallet handling mechanisms, do not need to turn in an aisle to access pallet locations, and in APR can typically operate in aisles of 1.8 meters or less.
They can also lift higher (up to about 20 meters) than reach trucks, and these two factors increase the space utilization. However, there are cost penalties in providing the required floor strength and flatness for working in high but narrow aisles, and the trucks are significantly more expensive than reach trucks.
Nevertheless, narrow-aisle racking systems are very common in warehouses with large pallet reserve storage areas.