Tailor-made sealing systems for the Fehmarnbelt immersed tunnel

Trelleborg’s marine and infrastructure operation has been awarded the contract to supply its tunnel seals to Femern Link Contractors (FLC) for the construction of the 18-kilometer long Fehmarnbelt tunnel. Connecting Rødbyhavn in Denmark and Puttgarden in Germany, once completed it will be the world’s longest immersed tunnel.

[@u1zha]

Curious what's the plan when the seal reaches the end of its lifetime after all. Is there a fancy way to refurbish the connections between segments from the inside, without digging up the sea floor?

[@24jh42]

There is the Limfjordstunnel. A 582 meter long tunnel built in 1969 en.wikipedia.org/wiki/Limfjordstunnelen . Connecting North Jutland to the mainland. In the entirety of its existence it has struggled. The rubber membrane never worked properly and saltwater erodes the concrete the membrane was supposed to protect. Additional problems is poor quality concrete. Terrible construction method during the build. Movements in the seabed causing the tunnel elements to shift and slowly drift apart. Not a year goes by without extensive maintenance and renovations mostly done at night so that both north and south bound traffic is led through the same tunnel pipe, while they work on the other. Point is they do all this work from the "inside" of the tunnel. When the tunnel elements is placed and covered with sediments that is it. You live with the problems and when the cost and problems exceeds the benefits, then you scrap that tunnel or built a new.