When the three largest lock doors in the world were constructed for fitting at the new sea lock in IJmuiden, Mammoet devised a series of unique solutions to transport the three lock doors and a 255 ton dry dock door from the South Korean construction site to the installation point at IJmuiden in the port of Amsterdam.
After almost 100 years in operation, the Northern Lock at IJmuiden is to be replaced with a new, larger lock system that will improve access to the port of Amsterdam. Rijkswaterstaat, (part of the Dutch Ministry of Infrastructure and Water Management) commissioned the ‘OpenIJ’ group of contractors to build the new sea lock.
Each lock door weighs 3,000 tons and measures approximately 72 metres wide, 24 metres high and 11 metres thick – making them the largest lock doors in the world. Transporting the enormous doors from their Korean construction site to Amsterdam, therefore, posed an unprecedented challenge.
Mammoet was involved from the beginning to design a safe and efficient transport and lifting process. The approach involved a semi-submersible vessel to which the doors were floated out, using pontoons and a tailor-made lifting system to ensure stability. Custom-made sea fastenings facilitated the process. On top of that, stabilising steel ballast was placed on the doors before floating them off to the semi-submersible vessel, on which they were transported to the port of Rotterdam.
Project manager Raymond van Dijk says: “Stability of the lock doors was critical, so Mammoet modelled and weighed the locks to determine their centre of gravity and centre of buoyancy. This allowed us to calculate how ballast could be applied to maximise stability during float-off.”
After float-off at the port of Rotterdam, the lock doors were connected to a sheerleg floating crane and two 700-ton mobile cranes and raised from their horizontal position to an upright position, to make transport over sea safer. The doors were water ballasted to increase stability, then towed by tug from Rotterdam to IJmuiden, Amsterdam. There the electrical and hydraulic systems will be installed. Once they are ready, Mammoet will install the doors at IJmuiden at the new sea lock. The sea lock will be completed at the beginning of January 2022.