Project Profile: U5 Underground Line Extension, Berlin

The U5 metro line extension in Berlin represents a significant urban rail infrastructure achievement, closing a critical 2.2km gap in the city’s U-Bahn network. This project delivers a vital east-west transit corridor by connecting Alexanderplatz to the Hauptbahnhof (Central Station), enhancing network resilience and providing direct access to major cultural and governmental landmarks.

Technical Specifications

The 2.2km extension establishes a direct east-west connection through Berlin’s historic center. Construction in the dense urban core necessitated advanced engineering methods. The twin-tube tunnel was excavated using a 700-tonne shield tunnelling machine (TBM) to minimize ground settlement and protect historic buildings above. Station boxes for Rotes Rathaus, Museumsinsel, and Unter den Linden were constructed using the cut-and-cover method, requiring complex logistical planning.

The Museumsinsel station presented a unique geotechnical challenge, as it was constructed directly beneath the Spree Canal in highly saturated soil. This required extensive ground freezing techniques to create a stable, impermeable block of earth, allowing for safe excavation. The Unter den Linden station was designed as a crucial three-level interchange, seamlessly integrating the new U5 extension with the existing north-south U6 line, enhancing overall network connectivity.

Key Takeaways

• Closing a Strategic Network Gap: The project completes the U5 line, creating a vital east-west corridor that connects major residential areas in the east with the central government district, main station, and key tourist destinations.
• Enhancing Urban Accessibility and Tourism: The three new stations provide direct, barrier-free access to UNESCO World Heritage site Museum Island, the Brandenburg Gate, and the Reichstag, significantly boosting tourism and improving mobility for all residents.
• Showcasing Advanced Urban Engineering: The project successfully navigated complex geotechnical conditions, including tunneling under the Spree River and through sensitive historic areas, by employing state-of-the-art techniques like shield tunneling and ground freezing.

Frequently Asked Questions (FAQ)

When did the Berlin U5 extension open?

The Berlin U5 underground line extension, connecting Alexanderplatz to Hauptbahnhof, officially opened for passenger service on December 4, 2020.

Who built the Berlin U5 extension?

The U5 extension was managed by Projektrealisierungs U5 GmbH, a subsidiary of Berlin’s public transport operator, BVG. The project involved a consortium of engineering firms, including Vienna Consulting Engineers and CDM Smith, and architects like Collignon Architektur and Max Dudler for station design.