Fortress Gates are a barrier meant to block enemy troops from passing through while allowing friendly troops to enter, and is usually coupled with walls as an effective defense.
Gates have two variants; one that faces horizontally (east/west) and one that faces vertically (north/south).
GDI and Nod use different models of gates, although their statistics are similar to each other, like walls.
This structure prevents enemy units and Tiberium growth from entering a base. The gate automatically opens to allow friendly units to pass, but will not open for enemy units.