The special vessel that will immerse the elements for the Fehmarnbelt tunnel is undergoing its final tests prior to approval for use by the Danish maritime authority.
Last weekend, the unique immersion pontoon IVY 1 & 2 carried out the first test of connecting the vessel to a completed tunnel element. It was the first time a finished element was firmly connected to the immersion pontoons.
The immersion pontoons are currently located in the large Danish work harbour on Lolland, with the first tunnel element secured between the two units. The initial phase of testing has been completed and includes, among other things, confirming that all functions operate correctly – both when IVY 1 & 2 are operated separately holding a standard element secured in between, and when they are operated as a combined vessel.
During the final phase of testing, additional weight will be added to the secured element, corresponding to the amount of ballast concrete required to weigh the element down. IVY will then lower and raise the element for test purposes in the work harbour. The contractor consortium Femern Link Contractors (FLC) expects this phase of testing to be completed this month.
“IVY 1 & 2 is a completely unique vessel, built specifically for the tunnel elements used for the Fehmarnbelt tunnel. It has taken longer than expected to complete and test the vessel. FLC is now close to reaching the finish line, enabling the vessel to be approved to play the key role in the immersion of the tunnel’s many elements. We expect the first element to be immersed and connected to the tunnel portal at Rødbyhavn later this spring,” said Sund & Bælt deputy contract director Lasse Vester.
Once the vessel has been approved by the Danish maritime authority, IVY will bring the tunnel element to the quay in the Danish work harbour, where additional concrete will be pumped into the element. This will make the element heavy enough to sink to the seabed. From that moment, it is kept afloat solely by the buoyancy of the two immersion pontoons. IVY 1 & 2 will then transport the element to the tunnel trench and immerse it in a controlled manoeuvre with millimetre precision.
The 18km-long Fehmarnbelt tunnel between Denmark and Germany will comprise 79 standard elements and 10 special elements featuring a basement level for the tunnel’s technical systems.
IVY 1 & 2 are equipped with a total of 23km of steel wire distributed across 66 winches, which are used to immerse the element into the tunnel trench at depths of up to 40m.
In September last year, the Danish state-owned Sund & Bælt announced that challenges with the immersion vessel had delayed tunnel construction. Last month it cancelled tenders for the tunnel track and catenary and new tolling facilities because of the delay.
