Danish proceed with world’s longest submerged road tunnel
On Tuesday, the Danish government has given a ‘notice to proceed’ to the international building consortium that is to build a submerged tunnel between the islands of Lolland and Fehmarn (Germany) in the Baltic Sea. With 18 km of four-lane highway (with breakdown lane) and two rail tracks, it will be the world’s longest underwater road tunnel. Belgian dredger DEME is one of the key partners.
There are longer submerged tunnels in the world, starting with the Channel Tunnel (37,9 kilometers submerged) or Japan’s Seikan Tunnel (53,85 km but only 23,3 km underwater), and China is planning a 122 km long tunnel between Dalian with Yantai (100 km submerged). But these are all train tunnels only.
8,5 years to complete project
It took several years to get the Danish project ‘on the rails’ as getting the necessary permits was a long time coming, especially due to environmental protests on the German site. But finally, the die is cast, and the green light is given to start the €3,4 billion project in January 2021. A job that will take 8,5 years to complete.
The tender was won by Fernemn Link Contractors, a joint-venture with the French main contractor Vinci, Danish Per Aersleff, and a number of other companies, among which Belgian civil engineering group CFE with dredger DEME.
DEME to build concrete segments
The tunnel will consist of 79 concrete elements of 217 m long, weighing 73 000 tons, and 10 special elements with a double floor, housing tunnel maintenance equipment. These will be built by DEME onshore in a special factory at the Danish side, east of Rødbyhavn.
When assembled, the concrete elements will be sealed for floating and towed to their final location by tug boats. There, they will be sunk in the trench on the seabed. This trench will be up to 60 mm wide, 16 m deep, and 18 kilometers long. In total, some 19 million cubic meters of stone and sand will be excavated from the seabed. That, too, is right up DEME’s alley. The excavated material will be used to create three square km of new natural areas, mainly on the island of Lolland.
According to DEME’s spokesperson Vicky Cosemans in De Tijd, this project is a contract of €700 million for the Belgian dredger, who is going to engage several tens of people for this.
Driving at 110 km/h
When finished, cars will be allowed to drive up to 110 km per hour in the tunnel, making the trip as short as ten minutes instead of a ferry trip that today takes 3 hours and 24 minutes. Trains will be able to go as fast as 160 km/h (Germany) to 200 km/h (Danish side), linking the Danish and German islands in seven minutes.