Stack Interchange - Four-level Stack

Four-level Stack

The four-level stack (or simply four-stack) has one major road crossing another on a bridge, with connector roads crossing on two further levels. This type of interchange does not usually permit U-turns. Interestingly, the four-level stack creates two "inverse" dual-carriageways—the turn ramps crossing the middle section have traffic driving on the opposite side of oncoming traffic to usual (see diagram for clarity).