Single-vault station
The single-vault deep underground station is a type of subway station.
The construction of a single-vault station consists of a single wide and high underground hall, in which there is only one vault (hence the name). The first single-vault stations in the USSR were built in Leningrad in 1975: Politekhnicheskaya and Ploshchad Muzhestva. Also in Saint Petersburg was built the first and so far the only two-level single-vault transfer station in Russia: Sportivnaya.
In the Moscow Metro there is only one deep underground single-vault station, Timiryazevskaya, in addition to several single-vault stations at shallow depth. In the Saint Petersburg Metro all single-vault stations are deep underground, for example Ozerki, Chyornaya Rechka, Obukhovo, Chkalovskaya, and others. Most of the underground stations of the Bay Area Rapid Transit and the central stations of Washington D.C.'s Metro system are single-vault designs, as are all the single-line vaulted stations in the Montreal Metro. In Prague Metro, there is one underground station built as single-vault, Kobylisy.