To increase capacity standard APR systems can be designed into the Double Deep system. 

Double deep as the name suggests is a double configuration on the sides followed by 4x row configuration in the middle. Due to the setup however, selectivity drops to 50% as the pallet behind can only br accesed after removing the front one.

Special reach trucks or ones retrofitted with extendable forks are needed in order to access the pallets behind. In certain situations, the machine may also be fitted with straddle legs and require to go in the rack so attention must be paid to the  first level and be lifted off the ground on a pair of beams. In these situations it is also common to allow for some extra bay width for the straddle legs to fit properly.