The U5 underground railway line in Berlin, Germany, is being expanded from Hönow through Alexanderplatz to the Brandenburg Gate (Brandenburger Tor) to form the new U5 line.

The new railway line will close the gap between the existing U5 and U55 lines by creating a direct connection from eastern areas of Berlin to the central station, city centre, and government district.

BVG Berliner Verkehrsbetriebe subsidiary Projektrealisierungs U5 (PRG U5) is developing the project at an estimated cost of €525m ($594.3m).

The official groundbreaking ceremony of the project was held in April 2010. Construction works commenced in 2012 and the project is expected to be completed in 2020.

U5 underground line extension route details

The gap closure will increase the total length of the U5 line to 22km, making it the first fully accessible line to operate underground in Berlin. It will also improve mobility and reduce emissions in the inner city centre.

The U5 underground line extension project will involve the construction of a 2.2km-long double-track railway line from Hönow to Berlin’s central station Hauptbahnhof.

A number of landmarks will be made easily accessible with the gap closure, including Television Tower at Alexanderplatz past the town hall Berliner Rathaus, St Mary’s Church, Neptune Fountain, historic Nikolaiviertel, Museum Island, Berlin Cathedral, German Historical Museum and State Opera, and Brandenburg Gate.

The new line’s route will originate at Alexanderplatz and run below the Marx-Engels-Forum, the Humboldt Forum, the Spree, and the Spree canal. It will then run beneath the Unter den Linden boulevard to Brandenburger Tor underground station.

Details of new stations on the U5 underground line extension

The U5 gap closure will add three new underground stations, namely Rotes Rathaus, Museumsinsel, and Unter den Linden.

“Unter den Linden will be built underneath the junction of Unter den Linden and Friedrichstraße and will serve as a new interchange for the U5 and U6 lines.”

Rotes Rathaus will be a two-level station situated in front of the city hall beneath Rathausstraße between Spandauer Straße and Jüdenstraße. Platforms will be located at the upper level, while storage siding will be placed at the lower level, substituting the reversing loop at Alexanderplatz.

The station will feature modern black and white design with seven centre columns, which will be shaped like mushrooms. It will integrate a single island platform with a spacious concourse with a modern black and white design. The station will also feature lifts and escalators for easy flow of passengers.

Museumsinsel will be located below the Spree canal towards the southern portion of the Palace Bridge. It will feature arched dark blue ceiling with spotlights.

Unter den Linden will be built underneath the junction of Unter den Linden and Friedrichstraße and will serve as a new interchange for the U5 and U6 lines. It will have three levels, with U6 running at the top level and U5 at the bottom level, while the middle level will house a concourse.

Construction of new stations

The excavation pit for the new underground stations is being built using cut-and-cover top-down method and is supported by walls of reinforced concrete. A waterproof floor is then built to create the bottom boundary.

Work includes the creation of a connection to the existing Alexanderplatz reversing loop. Track laying and cabling installation works will be performed upon completion of the basic structure.

Ticket machines, ticket-cancelling posts, and information displays will be installed during the final stage of construction.

The tunnel between Marx-Engels-Forum to Brandenburger Tor station will be built using the shield tunnelling method and will feature two separate main tunnel tubes.

U5 underground line contractors

Collignon Architektur is responsible for designing the Rotes Rathaus underground station of the U5 underground line extension.

Collignon Architektur, Vienna Consulting Engineers, CDM Smith, Max Dudler, Axel Oestreich, and Ingrid HentschelConsulting Engineers and a consortium of artus Architekten and Schüsslerplan carried out project control, site management, site supervision of structural works, finishing works, and cable routing of the Rotes Rathaus underground station.

Swiss architect Max Dudler provided design for the Museumsinsel underground station, while the Unter den Linden station was designed by Axel Oestreich and Ingrid Hentschel.

CDM Smith provided consulting services for the U5 underground line extension project.