The construction of the Hartel barrier was necessary when one decided to build a barrier in the New Waterway. When the Maeslant barrier closes, in extreme situations, too much sea water could threaten the ‘Europort’ area. lying behind. Consequently, one built a storm surge barrier in the Hartel canal, near Spijkenisse. The moveable barrier contains slides which are hung between towers. The shape of the slides and towers is somewhat unique: the slides are made in the shape of an ellipse and the towers are oval. When there is an exceptional storm, the slides can be lowered into the water.
The special thing about the Hartel barrier is that the water flows over the barrier. Consequently, the slides have to face forces of different strengths and from different directions. The designers of the barrier were challenged to construct the barrier in a way that it would survive even the heaviest storms. Too much trembling and moving was not allowed. The barrier also needed to meet certain demands when it was open. The slides would catch a lot of wind due to their unique shape and large surface area.
There is a control portal on each side of the Hartel canal. Another portal stands in the middle of the canal. The three portals are positioned on the piers of the bridge than runs above the Hartel canal. The openings between the portals are 49.3 and 98 metres wide. When the barrier is open, the slides hang about fourteen metres above sea level. This is a little higher than the bottom of the bridge. When the slides are lowered, they can handle a water level of 3 metres above Amsterdam ordnance zero. When the Hartel barrier was built, the lifting cylinder that was used was the largest in Europe.
When to close?
The Hartel barrier is not closed without reason. The computer system BOS decides whether or not the barrier needs to be closed. The circumstances can often be determined more objectively by a computer than by human beings. It was calculated that the barrier would need to be closed about once or twice every ten years at the most. This frequency will probably increase in the future due to the climate changes, in which bad weather occurs more often. When the barrier is closed, no ships can pass through the Hartel canal. When the barrier is closed, the locks that are lying next to it, are also closed. Every two weeks, checks are made to ensure the slides can still move. The slides are simply moved a few centimetres. This way, defects can be traced early and prevent unpleasant surprises during bad weather.