Dutch Engineering Spotlight - The Maeslantkering

In the year 1916, a catastrophic spring tide from the North Sea overwhelmed the coastal defences of the southern Dutch coastline. In response, the government issued a 20 year construction project for tender, to shore up the dikes and dams around the lowlying provinces. Despite all this, in 1953 history repeated itself when an overnight storm surge flooded just under 10% of the country and killed more than 1800 people. It also killed over 100,000 livestock and destroyed the homes of 72,000 people. The Dutch still refer to the event as 'De Ramp', which literally means 'The Disaster'.

Determined to never have a disaster like this repeat itself, the Dutch government issues construction orders on the largest single civil works project ever undertaken in the West until that point in history - The Deltaworks. The Deltaworks dammed all the major waterways in the South of the country and the coastline through from Zeeland to North Holland, reducing the effective coastline of the country by 700 km. The crown piece of this project was the Maeslantkering.

The concept of the Maeslantkering was first proposed by a Dutch engineering collective decades before, but was deemed to be of a scale so unprecedented it could not be achieved. For the purpose of the Deltaworks, it was redesigned by architect Wim Quist. It consists of a monolithic gateway with two swing arms, resting on either side of the canal they are to bar. Each arm is itself the largest moving man-made object ever built, being as long as the Eiffel Tower is high and weighing twice as much. To this day it is a staggering piece of work.

When the canal is to be sealed, the gates are pushed out into the canal with two trains. In the middle they meet, lock together, and fill internal ballast cavities with seawater to settle on the canal bed and form an impenetrable wall. This process takes a total of 3 hours from the start of operations, at which point the gate can withstand a combined 102 thousand metric tons of external pressure. To re-open the gate , a bank of 22 windmills was re-purposed to drain the internal balast cavities, but these have since been replaced with 30 diesel pumps.

After an attempted hacking in the 60s, the computer system was rewired to function in a closed loop to prevent further cyber-attacks. Monitoring of sea levels is now fully automated, allowing the AI in charge of the barrier arms to close and open the gates entirely independently. This is key to the safety of the surrounding cities as even more dangerous than the gate not closing is the gate not opening - this would trap water coming down the Rein and Maas rivers upstream from the dam. To prevent against such eventualities, there is a division of the Dutch army (De Nederlandse Krijgsmacht) whose responsibility is the maintenance of an explosives depot nearby. This is to be used to blow up the barrier arms in case they fail to reopen.

Today, the Deltaworks are still the crown jewel of Dutch engineering prowess. However, with about one third of the country below sea level, the lowest point at 6.7 meters below sea level, and even the biggest international airport (Schiphol) 3 meters below sea level, the fight is ongoing. There are already plans in the works to add another 70cm to the height of the Maeslantkering to future-proof the defensive wall barring the north Sea from the country.

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Image credit, in order of appearance:
Watersnoodramp, Gtrovers
Maeslantkering Diagram, NYT