東急東横線
Tokyo Metro indicated in its public share offering that it would cease line construction once the Fukutoshin Line was completed. That line was completed in March 2013 with the opening of the connection with the Tōkyū Tōyoko Line at Shibuya Station, allowing through service as far as Motomachi-Chūkagai Station in Yokohama. There are several lines such as the Hanzōmon Line that still have extensions in their official plans, and in the past, these plans have tended to happen, though often over several decades.