It is now difficult to indicate what consequences this will have for the timetable.
The speed on the high-speed lines (HSL) in the Netherlands will immediately be reduced again, which means that travelers will spend up to three minutes longer on the road and there may be fewer trains running. The cause of this is the design errors in ten viaducts on the HSL, which now appear to be more unsafe than previously thought. ProRail has announced that trains may therefore only travel at 80 instead of 120 kilometers per hour.
In recent months, the investigations into the design errors in the ten HSL viaducts have been thoroughly examined again. This has led to new conclusions. ProRail writes: “During construction they were designed too light, so they are now no longer stable enough to drive over at high speed.”
design flaws
These new insights arise from recent studies into the structural design errors in the viaducts, which were constructed by the Hollandse Meren construction consortium. During the construction of the HSL, the viaducts were designed too light, which means they are no longer stable enough for high speeds.
ProRail regrets the situation that has arisen, especially because it is expected that this new measure will take trains two to three minutes longer. It is now difficult to indicate what consequences this will have for the timetable. “We will keep a close eye on this in the coming days. We may be forced to run fewer trains to ensure that the timetable remains reliable," said ProRail.
Normally trains on the high-speed route can travel up to 300 km/hour, but that appears not to be possible in the Netherlands. “More than two years ago we first noticed that something was wrong. When we investigated this further, we found two issues,” explains Chris Heutinck, civil engineering expert at ProRail.
“On the one hand, there is a problem with the horizontal stability of the bridge. The viaduct may not move too much during a train passage. This movement can be caused by three things: wind, impact load (for example due to unevenness of the rails) and centrifugal force. In this case, the latter occurs because the track on the viaduct is in a bend. Due to an unfortunate design, the deformation of the rubber pads becomes too great, causing too much lateral displacement. This causes cracks in the weld seams of the steel fixation structures of the bridge.”
monitor
This is not the only issue at the viaduct on the Zuidweg. “Another problem is the southern abutment of the viaduct. This is the last point of the viaduct, where the train returns to the track body. Due to soil movement, this abutment has been displaced by a few centimeters and the foundation piles are being overloaded. The abutment will therefore have to be replaced in due course. But that takes time. Until then, we must monitor that no major movements take place and that the bridge remains safely passable,” Heutinck continues.
The next step is to investigate whether the current speed of 80 kilometers per hour can be increased again to 120 kilometers per hour. This requires technical substantiation that demonstrates that it is safe to drive over the viaduct at a higher speed. But to return to the original speed of 300 kilometers per hour, more needs to be done. “We need to be out of service for this for at least two weeks. This means that no HSL trains can run between Amsterdam and Rotterdam. You don't make that decision lightly,” says Heutinck.
However, this is not the only problem on the HSL. “The viaduct is part of a standard design with the same design philosophy,” says Heutinck. “The same critical constructions have been applied to nine other viaducts between Hoofddorp and the Groene Hart Tunnel. There are therefore speed restrictions in more places on that section of track (120 kilometers per hour). So we have to continue monitoring in all those places.”
