World first for Mergor

19 July 2006

At present MERGOR is immersing 4 tunnel elements in Roermond for highway A73 in the Netherlands. The elements are built, floated, transported and immersed on a gravel bed in 2 phases. In each of the phases 2 concrete tunnel elements will be constructed.

The elements have a length of 27m a width of 27m and are 7.75m high. The weight of each element is 29.000 tons. Last May the first phase was carried out and the first 2 elements have been successfully immersed on the gravel bed.

After immersing and emptying the immersion joint of the first element problems in de foundation were discovered. MERGOR had a world first in having to lift the element again from the gravel bed. By doing a thorough analysis, a risk assessment and a solid execution, the project team succeeded in lifting the element. After solving the foundation problems the element was immersed again two weeks later.

At the moment the next 2 elements are built in the casting basin. The preparations for the second phase of floatation, transport and immersion are in progress. The floatation of the next elements is planned for week 39. The transport through the trench and the immersion of the last tunnel elements is planned for week 43 and 44.