Subway entrances are a part of civilian (and local based) subterranean transport. They are highly similar to the present day subway. This structure is an entry to the underground subway station which have access to available subway transport and its hub. In the time of war the subway is usually shut down and sealed to prevent intrusions. But an engineer can be called to the main subway station to reactivate the subway network. Once a subway hub is captured, the player may garrison up to three squads of infantry in any subway entrance. They may then be ungarrisoned from any other subway entrance on the map, allowing infantry to instantaneously travel between them. Unfortunately, being controlled by the central station, the engineer cannot reopen the containment system. Thus the subway cannot be used to bring reinforcement from outside the theater and can only be used as a mode of (infantry) transportation.
This building works identically to the GLAtunnel networks from Generals, albeit already constructed and only be able to be captured. Any faction can destroy the Subway entrance and the subway hub. When all subway hubs and entrances in the area are destroyed, infantry stationed inside are trapped inside.