OpenIJ consortium places caisson for IJmuiden sea lock


November 20, 2018 – The OpenIJ consortium, consisting of BAM-PGGM, VolkerWessels and DIF, has achieved a milestone in the construction of the new IJmuiden sea lock in the Netherlands, with the immersion of the caisson for the outer lock head into its final position.

A caisson is a watertight chamber, open at the bottom, from which the water is kept out by air pressure and in which construction work could be carried out under water.

The caisson, in and out of which the lock gates will slide, is the size of an apartment building, 80 metres long, 26 metres wide and 22 metres high.

It has been immersed centimetre by centimetre to the right depth, in a controlled manner, over recent months.


The caisson has been sunk into the ground using remote-controlled robotic arms to remove the underlying sand.

The fully automated process has been monitored using sensors, measuring instruments and cameras installed underneath the caisson.

The space beneath the caisson will now be filled with concrete.


The inner lock head caisson, measuring 80 metres long, 55 metres wide and 25 metres high, will be immersed into its final position using the same method in 2019.

Construction on the world’s largest sea lock began in 2016.


The new lock in IJmuiden, which will be 500 metres long, 70 metres wide and 18 metres deep, is a joint project between the Dutch Ministry of Infrastructure and Water Management, the province of Noord-Holland, the municipality of Amsterdam, Port of Amsterdam and the municipality of Velsen.

The new sea lock, commissioned by Rijkswaterstaat, is being built by the OpenIJ consortium. It will accommodate increasingly large seagoing vessels.

The existing North Lock will reach the end of its technical service life in 2029 and has become too small for today’s large seagoing vessels.

The new sea lock is tide-independent and can be used 24/7. It will allow new-generation larger vessels to pass through the North Sea Canal smoothly and safely.

A larger lock is expected to allow the Port of Amsterdam to grow from 90 million tonnes to 125 million tonnes of goods handled per year.



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