Berlin's 'orphan tunnel' rebuild finally begins: Spree to be drained to reconnect U5 after decade of isolation

A decade of isolation for U5

On 7 May 2016, the last train rolled through the 865-metre Waisentunnel under the Spree. By 2017, water ingress and severe structural damage forced the Berlin transport authority (BVG) to close the tunnel for good. For ten years, U-Bahn Line 5 (U5) has been physically cut off from the rest of the network. The tunnel's sole function was not carrying passengers but shuttling trains between U5 and the western workshops for mandatory overhauls. Without it, each train unit has had to be split, loaded onto low-loader trucks, and driven across the city, a process that turned a one-day job into a two-week affair, according to BVG CEO Henrik Falk.

The logistically bizarre repair cycle

Falk described the road transport of individual train cars as "far from efficient" and "a huge impact on the stability of the entire network." The BVG's project manager, Dennis Backwinkel, noted that the Waisentunnel is the only rail link enabling U5 stock to reach the workshop in Britz, from where it can continue to Seestraße. Conversely, trains from other wide-profile lines (U6-U9) depend on the tunnel to reach the eastern workshop at Friedrichsfelde when capacity is tight. Since the closure, the BVG has been operating with a fractured logistics chain, adding strain to maintenance schedules.

The new tunnel: cost, timeline and river intervention

The replacement project now has a symbolic start. The new concrete tube will replace the century-old structure, which Backwinkel said is "disintegrating" and beyond repair. The total cost is set at 100 million euros, including the reconstruction of the connecting track between U5 and U8. The contract award is expected next week, and actual construction will begin in late summer 2026, with completion targeted for the end of 2030. A striking feature: part of the Spree will be drained, and the river will be half-blocked during works. The BVG had previously tried twice to secure the necessary permits from the waterways authority, which feared disruption to shipping; in 2006, 3,500 cargo vessels and 15,930 excursion boats used this stretch.

Political headwinds and a decade of delays

Even by Berlin standards, progress was glacial. The project was first floated shortly after the closure, but faced resistance from the SPD-led coalition in 2021, which insisted on examining "all alternatives." Sven Heinemann, an SPD budget politician, had voiced scepticism about the initial 50-million-euro estimate, saying "as a budget politician, I put a question mark on that. It can't be done for under 100 million."

Verweigerungshaltung

Traffic Senator Ute Bonde (CDU) criticized what she called a refusal attitude in politics. The tunnel finally received building permission in January 2026, and the long wait ended with Monday's ceremony under Littenstraße.

What it means for riders and network reliability

Passengers will never see the tunnel; it remains a service-only connection. Yet the BVG insists the rebuild is "a key project" for operational stability. Once completed, trains can be moved flexibly across workshops, cutting maintenance turnaround from weeks to days. Henrik Falk summed up: "It's finally starting." And while the tunnel may not be "sexy," as he put it, the restoration of a seamless rail link should keep more trains in service and fewer on flatbed trucks.