The Fehmarnbelt Tunnel’s special vessel has completed a crucial load test and is now ready to immerse the first special element with a basement.
Femern Link Contractors has already immersed three elements in the tunnel trench in the Fehmarnbelt. The specialist vessel IVY is now berthed in the work harbour at Rødbyhavn with the fourth element secured in place. Once the element has been immersed, the first approximately 900m of the 18km tunnel between Denmark and Germany will be in position.
The fourth element was used in a crucial test to demonstrate IVY could handle the next, fifth element, which is the tunnel’s first special element. It is shorter than the standard elements but has a basement containing technical installations for the tunnel.
At 39m long, 47m wide and 13m high, the special element is equivalent in size to a four-storey building.
“The first special element is the size of a multi-storey building and must be positioned at a depth of more than 20m. Immersing such a large structure is a demanding operation, which is why it was necessary to test IVY thoroughly before deploying the vessel,” said Sund & Bælt deputy contract director Lasse Vester.
The Fehmarnbelt Tunnel consists of 79 standard elements, each 217m long, and 10 shorter special elements with a basement. The special elements are positioned at intervals of approximately 2km. As well as housing the tunnel’s technical installations, at road level there is space for a service vehicle to stop without obstructing traffic.
The special element’s basement level requires it to ride higher in the water during transport. When the element is lifted further out of the water, buoyancy decreases and the load on IVY increases. The test simulated this additional load.
During the test, the fourth element was loaded with an additional 1,600 tonnes. The weight was distributed between large water bags on top of the element and tanks inside it. To pass the test, IVY had to be able to lift the element to the same height required when transporting the special element.
“The test was a rehearsal for a highly complex technical operation. We now know that IVY can handle the additional load and immerse the special element safely and precisely on the seabed,” said Vester.
