The construction of the 27km long Immersed Tube Fehmarnbelt Tunnel linking Denmark and Germany took another major step forward on Thursday 21st September, when construction consortium Femern Link Contractors, FLC, switched on the pumps that will fill water into the three large basins at the tunnel factory in Rødbyhavn.
The Fehmarnbelt project is the largest construction site in Northern Europe, and the filling of the basins is part of a complicated process that must be completed before the tunnel elements can be shipped out next year.
“Our contractors have been working on the basins for more than two years, so naturally we have all been anxious to start filling them. It is always exciting when you do something for the first time, and the basins play a key role in the project. Their size alone makes this a spectacular day on the construction site”, says Anders Wede, Construction Manager at Femern A/S.
The water filling is done gradually in a carefully controlled process so as not to damage the barriers between the basins, and it is therefore expected to take up to a week before they are completely full. The pools are also of a size not seen anywhere else in Northern Europe.
Each basin has a depth of almost 11m and together they hold around 1.6Mcubic metres of water.
The tunnel factory has a total of six production lines, and here the casting of the first of a total of 89 tunnel elements has begun.
The basins are the link between the factory and the work harbour, from where the elements are shipped out. Large gates ensure that the dry dock and basins can be filled with water and emptied as needed, allowing the elements to float from the factory to the work harbour and further out into the Fehmarnbelt.
“With the filled basins, the tunnel factory is close to complete. The two large gates that will control the water level in the basins are well underway, and inside the factory we have started casting the tunnel elements. The next big milestone will come next year, when we will ship out the first finished element”, says Anders Wede.
The first tunnel element is expected to be immersed in 2024.
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