[2] As the Hollandse IJssel is an important shipping route, the option of permanently closing the river with a dam was not taken forward.

However, the potential advantages of a closure included increased supply security of drinking water for large parts of South Holland, by reducing the inflow of seawater into the polders.

A storm surge barrier with two movable sluice gates, suspended between concrete towers, was chosen as the solution.

The sluices are only closed at periods of very high water, with shipping able to sail underneath the raised gates at other times.

[8] The project was designed such that the two gates could be operated independently, minimising the risks from failure and permitting regular maintenance.

[3] The total construction cost of the Hollandse IJssel Storm Surge Barrier amounted to approximately forty million guilders.

The Maeslant barrier is designed for very extreme floods (when the water level is predicted to be 3 metres or more above NAP in Rotterdam).

The dikes behind the Hollandse IJsselkering can only cope with water levels up to 2.25 metres above NAP, and therefore it is closed more often than the Maeslant barrier - around 3 to 4 times per year.

Closure of the Maeslantkering is therefore reserved only for extreme high water levels and the Hollandse IJsselkering remains essential to Rijkswaterstaat's overall flood management strategy.