U5 Urban Rail Line Berlin

The district of Berlin-Mitte is getting a direct underground line to Berlin Central Station (Hauptbahnhof) and the residential areas in the east of the city. Stage 1 is to connect the U55 at the Brandenburg Gate with the existing section of the U5 at Berlin City Hall (Rotes Rathaus). By closing this gap, the U5 will be extended from Alexanderplatz to the Brandenburg Gate, where it will connect with the U55, which is already complete. The U5 and U55 will then become a single line: the new U5.

Implenia has been commissioned by the Berlin Transport Authority (BVG) to construct a track-switching point at the Rotes Rathaus, in addition to building the stations at Museum Island (MUI) and Unter den Linden (UDL), the connection at the Brandenburg Gate (BRT) station and the two-track tunnel sections between these stations.

Starting at the track-switching point, the approximately 1.6 km-long tunnels pass under the Spree river, Spree Canal and the Humboldt Forum at less than 5 m below the surface in some places. The tracks then run along the Unter den Linden boulevard to the BRT station.

The subsoil conditions are characterised by the highly aquiferous sand and gravel deposits of Berlin's Urstromtal or glacial valley. Hydroshield material with a fluid-supported working face and a diameter of 6.7 m are used to manage these conditions.

The shield tunnelling unit will first pass through the MUI and UDL station sections, which will require the subsequent removal of the tunnel lining in order to build the stations. The tunnels are made of sealed, 35 cm-thick reinforced concrete tubbing with an inner diameter of 5.7 m.

The platform hall at the MUI station near the Spree Canal is being built with mining-grade shotcrete protected with ground freezing. The tunnels are being connected to the existing BRT station with the help of ground freezing, a plain concrete diaphragm wall as well as jet grouting and sealing injections.

Due to its highly urban location in the heart of Berlin, disturbances from the construction site have to be minimised to the greatest possible extent. For this reason, the excavated material will be removed with barges on the waterways of the Spree.


Divisions performance

  • Total project volume for gap closure: approx. EUR 525 million.
  • Start of construction: 2013
  • Implementation: 2020
  • Excavation: total of 120.000 cubic meters
  • Tunnel boring machine: 700 tonnes, 74 meters in length