The world’s largest sea lock at IJmuiden counts on the reliability of steel to accommodate larger vessels and increase the Port of Amsterdam’s cargo handling capacity

The North Sea Canal provides a vital link between the Dutch city of Amsterdam and the open shipping lanes of the North Sea at IJmuiden. Since it opened in 1929 its Noordersluis lock has stood sentinel to comings and goings from the Port of Amsterdam – Europe’s fourth busiest.



It has served the port well, but with freight traffic and cruise ships getting ever larger, the Noordersluis is set to be replaced by a steel-built sea lock that will be available for use 24 hours a day, at all stages of the tide, and able to accommodate even the largest and most heavily laden container ships.

Commissioned by Dutch highways and waterways agency Rijkswaterstaat, the new lock will measure 500 metres in length, 70 metres wide and 18 metres deep. It will become the world’s largest sea lock when it is completed by OpenIJ – a consortium of construction firms BAM-PGGM, Volker Wessels, and infrastructure investor DIF – under a €500m contract.


Gateway to Amsterdam

The OpenIJ team’s design utilises water flowing through sluices in the enormous 77-metre-wide, 25-metre-high and 11-metre-thick lock gates themselves to empty and fill the lock, rather than the more traditional system of separate culverts. This is due to the restricted space around the new lock. There are 16 of these sluice openings, each of which measures 9 square metres.

Thanks to the large sluices, the lock’s huge steel gates will enable water to flow through them at 2-3 metres per second, ensuring a ship can pass through in just half an hour.


An artist’s rendering of the finished sea lock


“The transit time is dependent on several variables – including tide, additional ships, time needed for mooring– but half an hour would be about average,” says Rob Gordijn, environmental manager at OpenIJ.

This is not the only area where the design of the lock and its gates differs from the norm. In most cases the seaward gate would be larger than that on the landward side of the lock. But at IJmuiden the OpenIJ team took the decision to make its lock gates identical.

These huge steel structures must be robust enough to bear the huge, fluctuating water pressure behind each of them, and the impact from errant ships, for the next 100 years

With just one gate design the team only needed to fabricate one ‘spare’ replacement gate rather than the two required if both were different sizes. There is no specific corrosion protection for the steel gates from the harsh industrial and coastal environment other than a painted coating.

“The single sized gate design was an idea that we developed during the tender phase to reduce its overall cost,” explains Mr Gordijn, adding, “the ‘spare’ gate can be interchanged with either seaward or landward gates. This way we only need to fabricate three doors.”

Elsewhere, the three gates are being fabricated from structural steel by Geosung Tech at its base in South Korea. Each is fabricated in six sections, three upper and three lower blocks, before being moved out of the construction hall, connected at the firm’s fabrication yard and shipped out to the Netherlands. Each of the completed gates weigh 2,400 tonnes.


A steel-built engineering first

Steel plays an important part across the scheme. As reinforcement to the lock gate chamber walls and as sheet piles and tubular steel piles used in both the temporary and permanent structures.

Temporary sheet piles and tubular steel piles are being used in creating construction pits for the permanent lock structures, but there are parts of the permanent structures that are being constructed using steel sheets and tubular piles too. The new primary flood defence diaphragm wall structure between the new lock and the existing Middensluis will be constructed using a sheet/tubular steel cofferdam.

But it is the massive gates that really hold the key to the development of the world’s largest sea lock. These huge steel structures must be robust enough to bear the huge, fluctuating water pressure behind each of them, and the impact from errant ships, for the next 100 years.

When the new structure finally opens to shipping at the end of 2019 it will become an engineering first, but one that could yet be challenged. There is no technical reason why another, larger sea lock cannot be built somewhere utilising similar systems to those introduced by the OpenIJ team at IJmuiden – but it could be a few years away yet.


Images: OpenIJ / Rijkswaterstaat
Video: OpenIJ