History
Minami-Sunamachi Station opened on 29 March 1969 on the Teito Rapid Transit Authority's Tōzai Line, transferring to Tokyo Metro on 1 April 2004 with the agency's privatisation. Because the cut-and-cover work had to cross the very soft riverbed of the former Susaki River, builders used pneumatic-caisson techniques to sink 13 caissons under the watercourse and an inverted cut-and-cover method beneath a discharge channel. PASMO use began on 18 March 2007 and station-departure melodies were introduced on 5 June 2015. A long-running expansion to convert the line into a Spanish-solution two-island layout with three tracks completed its first track switchover on 11-12 May 2024, opening a new platform on 13 May; the full project is now planned for fiscal 2031.
History summarized from Japanese & English Wikipedia · last reviewed 2026-05-18.
Notes
Because the original tunnel runs directly beneath the buried Susaki riverbed, builders sank 13 pneumatic caissons of up to 26.5 metres apiece into the soft riverbed to construct the station.