Megaproject: Fehmarnbelt Belt Fixed Link

The tunnel will soon form a permanent connection between the islands of Fehmarn and Lolland, which currently depend on the well-known Puttgarden-Rødby ferry service. As a road-and-rail link, the Fehmarnbelt connection will become part of the Trans-European Transport Network and will make an important contribution to the green transition of the transport sector.

A megaproject like the Fehmarn Belt Fixed Link requires the best experts in the field. Since it was founded in 1988, TEC - the permanent collaboration between Royal HaskoningDHV and Witteveen+Bos - has been involved in the construction of most immersed tube tunnels across the world. The RAT joint venture, comprising TEC alongside Ramb0ll and Arup, was established in 2008. Ever since the project started in 2009, RAT has provided consultancy services and technical support to client Femern A/S. The latter company is responsible for implementing the project on behalf of the Danish government. Two building contractor consortia have been engaged for the civil infrastructure and engineering work: FBC (Fehmarn Belt Contractors, a consortium of Boskalis and Van Oord) is responsible for dredging the tunnel trench, constructing service harbours and creating new land. FLC (Femern Link Contractors) is responsible for building the tunnel production plant, the tunnel elements and the tunnel access ramps, and also installs the tunnel elements.

Arjen van Dalfsen, a structural engineer, is involved in the immersion tube tunnel project on behalf of TEC. He can list countless examples of the work we are undertaking for the tunnel project. Arjen: ‘The support TEC has provided to Femern A/S ranges from preparation of the initial draft designs and drawing up the contracts to the activities that are currently ongoing, such as checking the design document submissions and supervising the construction site. The work is incredibly diverse. In their hands-on roles, Esther Dornhelm and her colleagues, for example, literally have to wade through sticky clay. They oversee the quality of the dredging activities and land reclamation work and are involved in everything associated with rock (coastal protection), sand (land reclamation) and clay (dredging), including the removal of a 70-ton boulder from the tunnel trench. The team is now ‘on site’ and ‘on board’ daily to keep a finger on the pulse as the dredging work reaches completion.’

‘Personally, much of my time recently has been devoted to reviewing last-minute design changes that we receive from the tunnel production plant. And to developing a computer tool to assess changes to the tunnel alignment design in the light of the contractual requirements when the immersion process starts. Piet Barten, a highly experienced engineer and an old hand in the profession, has been working on the project for 15 years. He is currently reviewing a large stack of all kinds of civil engineering design documents and, with his extensive immersion tube experience, is one of the key sounding boards for Femern A/S's immersion tunnel team. Finally, Bas Bruins Slot, our ‘concrete doctor’, is involved in assessing the concrete mixtures, the curing behaviour and the quality of the poured concrete, with the remaining lifespan of the tunnel firmly in mind. These examples show just how diverse the issues can be.’

Construction work to build the tunnel access ramps on both sides of the Fehmarnbelt link started in the spring of 2023. A large tunnel production plant has been built in Rodbyhavn. Six production lines for making the concrete tunnel elements for the immersed tunnel are now in operation there. Nine segments make up a single 217-metre tunnel element, which is then immersed in a single operation. A total of 79 standard elements and 10 special elements will be manufactured. The first tunnel element was christened by King Frederick X of Denmark in the summer of 2024.

For the tunnel trench on the seabed, building contractor consortium FBC has dredged up nearly 15 million m³ of material with 70 work vessels and the largest dredging machines in the world. Building contractor consortium FLC is now in play and working to create the foundation in the tunnel trench with a vessel specially built for this purpose. Then the first tunnel element can be sunk into place against the access ramp on the Danish side. The contractor hopes to start this phase later this year, marking another important milestone in the completion of this megaproject.