Danish politicians finally gave the green light early 2011 for the construction of an immersed tunnel called the Fehmarn Belt as a fixed link between Denmark and Germany. Femern A/S has been entrusted with building and operating this major project. This firm, established by the Danish Ministry of Transport, commissioned the parallel development of bridge and tunnel designs. The tunnel design was produced by the Ramboll-Arup-TEC joint venture, in which Tunnel Engineering Consultants (TEC) - a consortium of DHV, Royal Haskoning and Witteveen+Bos - plays a major role.
World’s longest immersed tunnel
Femern A/S advised the Danish transport minister in late 2010 to opt for the undersea tunnel. It had been established that the costs of a tunnel were lower compared with those for a bridge, and that there would be fewer risks for the environment and shipping. The 19 km long Fehmarn Belt will thus become the world’s longest sunken tunnel. It will significantly cut the journey time between northern Europe and Scandinavia. The Fehmarn Belt is one of the largest infrastructure projects ever undertaken in Europe, and will provide a significant boost to the economic, cultural and social development of the region.
Estimate of building costs
The connection will have a two-lane motorway in each direction, complete with emergency lanes, a separate escape route, and a two-track railway tunnel. The construction costs have been estimated at 6.6 billion euro, including modifications to the existing land infrastructure on the Danish and German side. Design preparations are expected to take three years and construction a further six years, whereupon the tunnel is scheduled to open by the end of 2020. Witteveen+Bos made a major contribution to the design of the immersed tunnel and the marine works, focusing on such matters as wet earthworks and the immersion process. We also drew up the construction cost estimate for the project as a whole.
Dutch engineering knowledge
For TEC and therefore for Witteveen+Bos as well, the decision to opt for an immersed tunnel means ongoing involvement all the way to the final delivery of the project. This provides an excellent starting position for work on similar links where there is a need for the specific engineering knowledge that the Netherlands has in this field.