The Vienna U-Bahn (German: U-Bahn Wien), where U-Bahn is an abbreviation of the German word Untergrundbahn (English: underground railway), is a rapid transit system serving Vienna, Austria. The five-line network consists of 83.1 kilometers (51.6 mi) of route, serving 109 stations.[5] 459.8 million passengers rode the U-Bahn in 2019.[7]
The modern-day U-Bahn opened on 25 February 1978,[5][4] after test operations that began on 8 May 1976. Parts of two of the lines, designated U4 and U6, date back to the Stadtbahn ("city railway") system, which opened in 1898. Parts of the U2 and U6 lines began as subway tunnels built to accommodate earlier tram lines. Only the U1 and U3 were built wholly as new subway lines.
Lines are designated by a number and the prefix "U" (for U-Bahn) and identified on station signage and related literature by a colour. There are five lines; U1, U2, U3, U4 and U6. Since the late 1960s there have been numerous suggestions of routings for a line U5, but all these projects had been shelved until the construction of a new U5 was announced in early 2014.[8] Stations are often named after streets, public spaces, or districts, and in some special cases after prominent buildings at or near the station. The policy of the Wiener Linien, however, states that they prefer not to name stations after buildings.[citation needed]
Ticketing for the network is integrated under the Verkehrsverbund Ost-Region (VOR) along with other means of public transport in Vienna, including trams and buses. Local tickets are valid on S-Bahn suburban rail services and other train services but those are operated by the state railway operator, ÖBB. Tickets are not valid on bus services operated by Vienna Airport Lines or the City Airport Train express train.