Why the storm surge barrier?
On the night of January 31 1953, the lives of between 1 and 1.5 million inhabitants of the Randstad (the dense-populated area in the west of the Netherlands) were hung by a thread. An expert compared that night to a herd of elephants going through the eye of a needle. Although the dikes of the Hollandse Ijssel were in a very poor state, no real measurements were ever taken. This was strange, because the dikes situated north of the Hollandse Ijssel, had been broken through a number of times previously.
This happened for example in 1574, when the Beggars (the people who wanted to free the Seven Provinces from the Spanish occupier during the Eighty Years’War) pierced the Schieland's Hoge Zeedijk (Schieland’s High Seadike). Consequently, the Prince Alexanderpolder (with 6.3 metres below NAP, the lowest place of the Netherlands), was flooded and with it, the whole of South-Holland. The Beggars were then able to reach Leiden with their ships and free its inhabitants from the Spanish occupation.
On the night of January 31, 1953, water in the Hollandse IJssel rose up to NAP + 3.7 m. The dikes had an average height of only NAP + 4.0 metres and were in very poor condition. If the dikes had broken through that night, the consequences would have been disastrous. During the disaster in Zeeland, 1 in 40 inhabitants died. If the same disaster had happened in the Randstad, the number of casualties would have been between 25,000 and 35,000 people, compared to the 1835 deaths in Zeeland. This is 8 to 12 times the number of people that die in traffic accidents in the Netherlands every year. Something had to change, that much was clear. The Deltacommission advised to build a movable storm surge barrier in the Hollandse IJssel. Although this would involve very high costs, it would still be cheaper than a structural raising of the dikes along the Hollandse IJssel.
Eventually a design was chosen based on building a double storm surge barrier with two steel screens of 80 metres wide. These screens would be hung between two lift towers. In the case of unusual circumstances, these screens would be let down into the water. In the normal situation (as long as the water does not rise over NAP + 2.5 metres), the ships would be able to sail under the screens without problems.
Busy course of navigation closed?
In addition to the surge barrier, which was called the ‘Algerakering’, a screen lock was built. This lock had two functions: Firstly, ships could still sail in the case of a storm tide, and secondly, ships could still sail in the case of work being done on the barrier. It was very important to keep the Hollandse Ijssel open at all times. Because of its size and depth, the river was one of the most important courses of navigation for inland navigation to Germany.
A regular cross-river connection
The construction of the barrier was used to realise a regular cross-river connection. Before the barrier was built, there was only a ferry connection across the Hollandse Ijssel. Because the people living in the Krimpenerwaard often had to wait for a long time before they could cross the river, a bridge was built over the storm surge barrier. The section of the bridge that ran over the locks could be raised. The bridge over the two screens had the same height as the screens on their highest point. The bridge would not affect ships. Today, the N210 (a main road) runs over this bridge.