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.
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.
U5 (Berlin U-Bahn)