U5 (Berlin U-Bahn)

Before control of the U-Bahn network was handed over completely to the BVG in 1929, the Hochbahngesellschaft started construction on a final line that, in contrast to its previous lines, was built as part of the Großprofil network. It was supposed to be a branch for the U2, which starts from Klosterstraße in 1908. The E line ran under Frankfurter Allee, for which the company had received the concession in 1914, between Alexanderplatz and Friedrichsfelde before the World War II.

The construction work proceeded since 1927 without delay or undue expense, and the first servicing station was established in the eastern part of the city; the line opened on 21 December 1930, named Line E. The several stations do include:

• Alexanderplatz (interchange)
• Schillingstraße
• Strausberger Platz
• Memeler Straße (today's Weberwiese)
• Petersburger Straße (today's Frankfurter Tor)
• Samariterstraße
• Frankfurter Allee (interchange with S-Bahn)
• Magdalenenstraße
• Lichtenberg (interchange with Ringbahn)
• Friedrichsfelde (end terminus and depot)

Heavy bomb damage caused by Allied air raids and invaded water at the end of the war severely curtailed operations in the first post-war months. Thereafter, the trains of this line had to be sent as reparations to Moscow and replaced accordingly. Only in the 1960s were comprehensively new trains procured, until 1968 still small profile trains were still in use. Line E was the only purely East Berlin line. For a long time, it was planned to extend it beyond its former terminus Friedrichsfelde and to lead via Karlshorst to Oberschöneweide. Karlshorst was especially known for its villa colony. There, after the war, the Soviet military administration established itself. But both reasons were not sufficient to extend the line E to Karlshorst. Due to the large demand for housing in Berlin, a large part of the construction capacity was needed for housing construction.

The areas intended for housing included the areas west of the Tierpark zoo. For about 25,000 residents, 9,000 apartments were to be built here. To connect this residential area better to the city center, it was decided to extend the subway line E by one stop. In addition, about 2.5 million zoo visitors per year were expected. For these expected passenger flows, it was worthwhile to extend the subway.

During the time when Berlin was divided, the U5 was the only line to fall entirely within East Berlin, and the only line to be actively extended by the East German authorities. Work on this extension was started in September 1969. On 6 June 1973, the first extension was opened, to Tierpark station, serving the zoo.

Wuhletal, the connection between the S-Bahn and the U-Bahn

In the 1970s, there were also plans to extend the line over to Hellersdorf. For this purpose, the then district Marzahn was divided into Marzahn and Hellersdorf. Due to the large extent of the developing area, a rapid transit connection to the centre of East Berlin, Alexanderplatz was needed. For this purpose, several proposals were developed. The idea to build the S-Bahn, as done previously for the new residential areas in Marzahn and Hohenschönhausen, was rejected because the trams were already heavily utilised and could not accommodate another train group. An express tram, which was realised in Potsdam, would not have sufficient capacity. Only the extension of the subway (U5) fulfilled all the requirements. Again, there were several route variants. It was decided to run the underground above ground on the unused railway line of the VnK route (connection to Kaulsdorf). In addition, an interchange at Wuhletal for connection to the S5 S-Bahn line, was needed.

The extension was planned in the years 1983 and 1984. It would be 10.1 kilometers long and have nine stations. The new building, which was almost completely above ground, was opened in two sections. Construction began on 1 March 1985.

The final extension went into service on 1 July 1988 (Elsterwerdaer Platz) and 1 July 1989 (Hönow). The last two stations of the extension, Louis-Lewin-Straße and Hönow, were originally located outside Berlin city limit, in Bezirk Frankfurt. The area was joined to Berlin at German reunification in 1990.

All stations were designed by the Deutsche Reichsbahn (EVDR) design and surveying operations. For the first time, the stations were equipped with ramps to enable step-free access to platforms for passengers with prams and wheelchairs. At Hellersdorf a connection to the local tram was created: the stops islands can be reached via a tunnel, the crossing of the street is thus eliminated.

After reunification, the U5 was upgraded to the new signalling system under Systemtechnik für den automatischen Regelbetrieb (STAR). The test stretch is from Friedrichsfelde to Biesdorf-Süd, using H-Zug trains, which were introduced from 1996 to April 2000. The Class H, used on the U5 can be converted to fully automatic train operation, and there is still a Bombardier test train, built in 1995, who can drive the train automatically.

In contrast to the testing with LZB 501 on the U9 line as well as SelTrac on U2 and U4 lines, which used transmission of information between route control and the train using line conductor loops (Linienzugbeeinflussung), STAR made use of radio technology (Funkzugbeeinflussung).

When the Berlin Senate reiterated in 2002 that the U5 should initially not be extended further, the BVG announced that it would no longer pursue the automatic operation project. An operation on the U5 Alexanderplatz - Hönow would have made little sense according to the BVG. At that time, the BVG was the technology leader. The underground lines U2 and U3 of the Nuremberg U-Bahn are the first automated subway lines in Germany since 2008 and 2010, respectively. In the previous 1980s driverless operation on the U4 a driver continued to be present but supervised the ride only.

At reunification, the line was renumbered as U5 to match the naming system in use in West Berlin. Between January 2003 and December 2004, reconstruction was conducted between Alexanderplatz and Friedrichsfelde in order to repair damage dating back to World War II. Not all the stations were preserved as monumental value. 1330 meters of railway track and tracks were relocated. For this purpose, the train traffic on the route was interrupted for three months. The aim was to improve the quality of stay at the stations. The lighting has been renewed and brighter, the technology has been brought up to date, the plaster has been extensively renovated and the walls have been clad in vandalism with enamelled sheet steel. The BVG took over Grenander's principle of identifying colors, but chose new color patterns. Numerous metro stations have been equipped with lifts and barrier-free. An example of a completely new design, including the rebuilding of the northern end of the station, is the Schillingstraße station.

In time for the International Garden Exhibition 2017, and neighboring "gardens of the world", the station Neu Grottkauer Straße was redeveloped in the spring of 2017 to provide a lift, new roof and new lighting, and renamed Kienberg (Gardens of the World). The renaming occurred at the timetable change in December 2016. The cost of all measures has been estimated at around € 6.6 million.

The latest stations, built between 1973 and 1989 from Tierpark to Hönow should be placed under monument protection, with the exception of this is the already significantly changed subway station Kienberg (Garten der Welt).

A refurbishment of the other aboveground stations built in GDR times is not planned before the middle of the 2020s. Equipped with elevators for fully accessible access is not planned until the lift program is completed on the rest of the metro network. The existing ramp systems with a slope of around 10% are only considered as barrier-free.

There used to be former U5 running from Deutsche Oper to Richard-Wagner-Platz, from 1 March 1966 to 1 May 1970. Before 1966, it was numbered A^I and B^I and the branch line as A^III. In 1970, the stretch was closed and in 1974, the station was demolished.

In the long term, there are plans to extend the line from Berlin Hauptbahnhof, via Turmstraße and Jungfernheide to Flughafen Tegel. This plan was postponed due to the route being too long, the pending closure of Tegel Airport and the poor fiscal position of Berlin. An addition to the plan is an extension towards Rathaus Reinickendorf via Cité Pasteur Nord, Scharnweberstraße and Eichborndamm.

The stations that were involved in the extension include:

• Alt-Moabit
• Turmstraße
• Huttenstraße
• Goslarer Platz
• Jungfernheide
• Hakenfelde
• Urban Tech Republic
• Cité Pasteur Nord
• Scharnweberstraße
• Eichborndamm
• Rathaus Reinckendorf

As of September 2016, the longer extension has been replaced by the tram extension from Hauptbahnhof, via Turmstraße, Mierendorffplatz, Jungfernheide, and towards the Tegel Airport, which might be redeveloped into a new Urban Tech Republic development, after Tegel Airport is closed, thus allowing the U5 to be shortened to just Berlin Hauptbahnhof. The possibility of extending the tram line to Cité Pasteur Nord, Scharnweberstraße and Eichborndamm to Rathaus Reinickendorf is still there in the vision stage. The tram extension was planned to be completed just before 2028.

At Jungfernheide, two island platforms were constructed for the planned interchange station between U7 and U5. The finished section is used for firefighting exercises in conjunction with airport security and the BVG. Trains that are used include 2712/2713 ('9 Zoolog. Garten') and 2714/2715 (Jakob-Kaiser-Platz), of which they were vandalised with legal spray painting. During the opening of 1980, Jungfernheide was in a deadlock because of the Berlin Wall, that prevented U5 from extending towards the west.