However, the council has yet to finalise its preferred route and two options are still under review. The first involves constructing Line D as an 8km seven-station branch off the existing Line C near Pancrác station, which is expected to cost around Koruna 24.7bn ($US 1.3bn). Alternatively, the line could be constructed as an independent route at a cost of Koruna 29bn.

The council expects to make a decision on the route next spring and construction could begin in 2017 if an application for European Union funding is successful. Commercial services are expected to start in 2022.