In 1906 the
Senate of Hamburg awarded a contract for the Elevated and Underground Railway to
Siemens & Halske and
AEG of Berlin. The first stretch was completed on 7 October 1906. This was followed in 1911 with the founding of the
Hamburger Hochbahn Aktiengesellschaft (HHA). Thus Hamburg became the third German city (after Berlin, 1902 and
Schöneberg,
1910) to have a
U-Bahn (then known as the Elevated and Underground Railway (Hoch- und Untergrundbahn) as it is largely either elevated or in tunnels – not much at street level). The construction of such a railway had long been discussed, meanwhile an elevated train was also considered. In 1906 a circular route was begun, connecting
Hamburg Hauptbahnhof – Berliner Tor – Barmbek (earlier spelling: Barmbeck) – Kellinghusenstraße – Schlump – Landungsbrücken (earlier designation: Hafentor) – Rathaus – Hauptbahnhof with branches to the quarters of
Eimsbüttel,
Ohlsdorf and
Rothenburgsort. On 15 February 1912 the first stretch of the future
Ringbahn (Circle railway) between
Rathaus station and
Barmbek was inaugurated. The stretch included both underground and elevated sections. File:U-Bahnhof_Überseequartier,_View_from_West_Entry_20131231_1.jpg|Übersee-quartier station File:Hamburg.UKlosterstern.wmt.jpg|Klosterstern station File:Hamburg U-Bahn Hauptbahnhof Nord.JPG|Hauptbahnhof Nord station File:U-Bahnhof Steinstraße 1.jpg|Steinstraße station
Network development By 1915 the Ringbahn and the three spurs, from
Kellinghusenstraße to
Ohlsdorf, from
Schlump to
Hellkamp (today: disused station between
Oster- and
Lutterothstraße) and from central station to
Rothenburgsort were completed. By 1934 the extensions from
Ohlsdorf to
Ochsenzoll (
Langenhorner Bahn), from
Kellinghusenstraße to
Jungfernstieg (KellJung line), and the
Walddörferbahn (Forestvillages line) from
Barmbek to
Großhansdorf and
Ohlstedt were completed. In 1943, during the Second World War the subway was badly damaged during 'Operation Gomorrha,' the
RAF bombing of Hamburg that summer. The stretch from
Hauptbahnhof to
Rothenburgsort was not repaired because the district it passed through had been completely destroyed. It was five more years before the remaining network was once more completely intact. Further additions to the network were made, starting in 1960. The KellJung line was extended via
Meßberg to the central station (Hauptbahnhof). Later in 1962 the extension reached
Wandsbek Markt and in 1963
Wandsbek-Gartenstadt. The total network length was . The construction of a
Durchmesserstrecke (diameter route) began in 1963. The plan was to connect
Billstedt with Stellingen. The Eimsbüttel branch formed the western part of the line. The branch was extended up to
Hagenbecks Tierpark in 1966. The existing terminus at
Hellkamp was withdrawn from service in 1964 and a new station was built at
Lutterothstraße further northwest. The connection between
Berliner Tor and
Horner Rennbahn was opened in 1967. In the same year this eastern branch was extended to
Legienstraße. Further extensions took place in 1969 to
Billstedt and in 1970 towards
Merkenstraße. The extension
Ochsenzoll – Garstedt came into service in May 1969. Thus, the network total length reached . A new core stretch of the line
U2, between
Schlump and
Berliner Tor, became a direct connection through the city centre. Next to be brought into service were sections from
Hauptbahnhof Nord to
Berliner Tor in 1968, and from
Schlump (low) to
Gänsemarkt in 1970, then the last section, with two new platforms on the lowest level at the station
Jungfernstieg under the
Binnenalster, in 1973. This station, as well as
Hauptbahnhof Nord, was developed as part of the
U4 line that was planned at that time. In 1985 the section to
Hagenbecks Tierpark was extended to
Niendorf Markt and again in 1991 as far as
Niendorf Nord. In 1990 the extension
Merkenstraße – Mümmelmannsberg was opened. The line extension opened in 1996 between
Garstedt and
Norderstedt Mitte, which replaced the southern part of the
Alsternordbahn. In 2005 the Hamburg U-Bahn had a length of some , of which are underground. It had 89 station stops. In 2009, the
U3, beginning in Barmbek, traversed the complete ring line, thereby taking over the stretch between Berliner Tor and Barmbek, which was formerly served by the U2. In order to realise a problem-free service, a redesign of the current track layout to the west of Berliner Tor was necessary. An originally planned
grade separated crossing of the two lines was realised, which was left undone before due to cost. Trains coming from the city centre leave the ring at Barmbek and continue via the viaduct stretch to Wandsbek Gartenstadt. One branch leads via the Walddörferbahn to Wandsbek-Gartenstadt, a stretch formerly served by the U2. In 2012, the
U4 started operations between Billstedt and
HafenCity University, sharing most of its route with the U2 and thereby increasing service on the highly used line between
Berliner Tor and
Billstedt. The U4 was extended further east to Elbbrücken in December 2018, providing a future S-Bahn connection. File:Hamburger Hochbahn - Entwicklungsgeschichte.png|Map showing the network development File:DT4 U-Bahn U4 Überseequartier - 3928-df3.jpg|U-Bahn ″Überseequartier″, rolling stock type
DT4 File:DT5_in_Richtung_Hauptbahnhof-Süd.JPG|U-Bahn station ″Baumwall″, rolling stock type
DT5 File:Hamburg U-Bahn Hochbahn.JPG|Hamburger Hochbahn on the
Vorsetzen == Future development ==