After almost three years of work, the excavation for the future Fehmarnbelt tunnel is now complete. The consortium FBC has executed the dredging works, consisting of the two Dutch companies Boskalis and Van Oord. At its peak, the combined fleet of FBC had up to 70 work vessels involved in the dredging of the 18 kilometre long tunnel trench.

In total, around 15 million cubic meters of soil have been dredged. That's the equivalent of six Cheops pyramids or 6,000 Olympic swimming pools. That the work is now finished is worth celebrating, says Pedro da Silva Jørgensen, technical deputy director at Femern A/S.

"It is by far the largest dredging operation in Denmark's history, and it has been a difficult task. The subsoil between Denmark and Germany is a complex mixture of different soil types from soft clay to hard limestone. This has given rise to some significant challenges along the way, which we have successfully solved in collaboration with our contractors. Therefore, we are happy and proud that we are now at the finish line", says Pedro da Silva Jørgensen.

During the operation, the dredgers have several times come across huge blocks of granite from the Ice Age, which have been particularly difficult to remove. One of the largest weighed 70 tons and is today setup on display next to the construction site at Rødbyhavn.

Bart Pröpper, Project Director of Fehmarn Belt Contractors: "Over the past three years, we successfully dredged the 18-kilometer-long trench for the future tunnel with an impressive variety of dredging equipment, ranging from trailing suction hopper dredgers, backhoe dredgers, specially developed and built grab dredge pontoons and boulder clearance vessels. On all these vessels, we made the necessary improvements to deal with the difficult soil types at great depths and get the job done in time. During the execution of this technically complex project, the safety of our employees and subcontractors was paramount, and we are therefore not only proud and excited about the completion of the tunnel trench, but also that we recently achieved a major milestone in safety performance.”

Most of the excavated soil has been placed behind dikes off the coast at Rødbyhavn as the work progressed. Here it creates 300 hectares of new land. In time, the new land areas will become a mixture of new nature and recreational areas with beaches and hiking trails.

However, FBC's role in the project is not quite finished yet. In the coming months, the contractors will remove the temporary dike in front of the tunnel portal, preparing the area for the immersion of the first tunnel element later this year.

The 18 kilometre long Fehmarn Belt tunnel is being built as an immersed tunnel, which is being constructed on Northern Europe's largest construction site at Rødbyhavn in Lolland. The tunnel consists of 79 standard elements that are 217 meters long and weigh 73,500 tonnes. In addition, there are 10 special elements containing the tunnel's technical installations in a special sub-basement.

The elements are produced on six production lines at the world's largest concrete factory. When the elements are ready, they are sailed out, lowered into the tunnel trench, and connected individually.

Femern A/S expects to immerse the first tunnel element later this year. The Fehmarnbelt Fixed Link will be completed by 2029. By then it will be possible to travel between Lolland and Germany in 7 minutes by train and 10 minutes by car.

https://femern.com/press/news/dredging-works-on-the-fehmarnbelt-tunnel-trench-completed/