Fehmarnbelt Tunnel Progress Hit By Delays and Setbacks

Work on the $8bn Fehmarnbelt Tunnel linking Germany and Denmark has reached a symbolic engineering milestone, even as the project confronts fresh delays that now push its opening further into the future and split its debut between road and rail.

Last month, crews successfully immersed the first precast concrete element of what is set to become the world’s longest immersed tunnel, marking a key moment in a scheme designed to transform transport links between Scandinavia and central Europe.

But Danish state-owned project developer Femern A/S has confirmed the programme is now running at least two years behind schedule.

The nearly 11-mile structure will run 140ft below the Baltic Sea between Puttgarden in northern Germany and Lolland in south-east Denmark.

Once complete, it will carry four lanes of road traffic and two electrified rail tracks through a five-tube corridor, alongside an access passage built within a dredged trench.

Journey times are expected to fall dramatically, with trains taking seven minutes and cars ten, cutting the current Hamburg–Copenhagen rail journey in half from around five hours.

At full scale, the engineering ambition is vast. Femern Link Contractors (FLC), led by Vinci Grands Projets SAS, has been manufacturing 79 standard concrete tunnel sections, each 712ft long, 138ft wide and 30ft high, weighing 73,500 metric tonnes apiece. 

A further ten specialist elements will house electrical infrastructure. Once completed, each segment is designed to be towed out by tugboat and lowered into a pre-dredged trench on the seabed before being locked into place.

The trench was created by a large dredging project. 

The Fehmarn Belt Contractors, led by Royal Boskalis Westminster and Van Oord, used about 60 vessels to dig up a massive amount of seabed between 2020 and 2024. 

They removed material from a wide, deep channel under the sea. Most of the dredged material is being reused to build over 700 acres of new land for nature and recreation.

Despite the scale of preparation, the project is contending with mounting logistical setbacks.

“Equipment issues force delays,” Fehmarn said in its account of the current situation, explaining that construction on the Danish side is roughly two years behind schedule due to problems with a vessel used to immerse the tunnel elements. The original opening date had been set for 2029.

READ MORE: Fehmarnbelt Tunnel Making Record-Breaking Waves

Compounding the situation are regulatory and environmental constraints in Germany. Transport authorities there have indicated that approval processes mean railway infrastructure linked to the tunnel cannot realistically be operational by 2029.

Strict German limits on underwater noise in its waters are also affecting construction timelines, with Femern and its parent company Sund & Bælt warning that recovering lost time will be difficult. A revised schedule will be published once more tunnel elements have been successfully placed.

As a result, the opening will now be staged. The road section is expected to enter service first, ahead of the rail line.

“A phased opening makes it possible to put the tunnel into use earlier for road traffic, while also reducing complexity in the final stage of the project,” said Sund & Bælt chief executive Mikkel Hemmingsen. He also acknowledged the downside: delaying the electrified railway “is unfortunate for the green transition and for rail passengers.”

Even so, work continues at pace across both sides of the strait, with thousands of workers engaged in construction and manufacturing.

FLC has established a large production facility in Rødbyhavn, Denmark, where more than 2,000 people are currently working across six production lines casting the massive tunnel segments. A further 100 workers are producing steel reinforcement cages nearby.

The first immersion operation itself began on May 4, when five tugboats transported specialised immersion pontoons IVY 1 and IVY 2 carrying the initial tunnel element on a short voyage of just over a mile to the Danish portal. 

Two days later, the element was lowered into place over about 14 hours.

Hydraulic arms guided the segment into place before crews connected it to the tunnel portal. Gravel was then placed on both sides to secure it.

Hemmingsen described that moment as one of relief as much as celebration. “Our technology, our equipment and our contractors have demonstrated their capabilities and achieved something no one has done before,” he said.

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