In the event of a fire, there is an acute danger to life in subway shafts. In addition to prophylactic fire protection, the functional safety of the emergency exits is of vital importance. At the “Weesperplein” metro station in Amsterdam, a sophisticated security system ensures that people get to the surface of the earth in a minimum of time. A former nuclear shelter plays just as important a role as the "Magnum" dampers from ACE shock absorbers.

Awareness of potential danger spots in public spaces has risen steadily throughout Europe in recent years and decades, which is reflected in corresponding security concepts. The greater the danger to life and limb, the greater the demands. If the people responsible also have to include potential crowds, such as in football stadiums or underground stations, in their disaster prevention plans, the requirements will increase again. At the Weesperplein metro station this meant that the locations were completely rebuilt. On behalf of the Gemeente Vervoerbedrijf (GVB), a wholly owned subsidiary of the city of Amsterdam, which also operates the 1977-built metro, the company JP van Eesteren BV was responsible for this. This company is one of the largest in the Dutch construction industry.

The Metro Amsterdam network covers a length of 42,5 km, of which four kilometers are underground. The Weesperplein underground station occupies a special position due to the existing nuclear bunker, as the planners were able to use a large network of escape routes through it. One of these protective paths seemed particularly predestined to reach the surface in the quickest possible way. So that as many people as possible get there safely in an emergency, it is very wide and ends at an exit that lies on a traffic island on a busy street. So that nothing is turned off on the exit or even parked, this is provided with a corresponding sign, because otherwise it could also hold "only" for a ventilation shaft due to the grid construction. For quite a big one though, with a mass of 4859 kg, the barrier grid located horizontally above the exit has considerable dimensions.

Industrial bumper with superhuman powers

Such a mass is not to be used by human hands, certainly not in an emergency. Instead, the large wire mesh has a non-central pivot point and opens immediately as soon as it is unlocked. This creates a lot of energy, which is to be slowed down at the end position, so that no one is injured in the emergency exit and no costly damage to the overall construction. This is where the ACE Stoßdämpfer GmbH, well-known through its own distribution network in the Netherlands, also comes into play with our neighbors, albeit via a detour. For at first the city of Amsterdam tried a solution from a competitor. However, this put the damper too small, which turned out to be wrong after later calculations. In one test, this resulted in one of the dampers being completely destroyed on the first impact. Even if it does not come every day to a fire in the subway, this is an unsatisfactory result.

In order to spare his customers further shock absorbers, engineer Bart Arends from JP van Eesteren contacted the ACE representatives for the Netherlands, Ralf Küppers and Han Titulaer. Since there was no exact information about the speed of the impact, the two turned on the headquarters in the German Langenfeld with a. There, the shock absorber product manager Christian Junghans and the technical consultant Stefan Bühler took care of the case. Both determined possible impact speeds through a series of 3D simulations.

As a result, MC64150EUM industrial shock absorbers were chosen to reliably decelerate the heavy-grid masses and keep them safely in check after opening. In this specific case, 5100 Nm per stroke and shock absorber can be reduced in energy and absorbed up to 63.700 kg of effective mass. The impact speed of about 1,8 m / s and the unusual impact angle of the exit grid, which can be seen in the pictures, pose no problems for the ACE solution.

In addition, because industrial shock absorbers, which have been part of the industry-standard Magnum family for more than a decade, can be easily integrated into existing designs, there is an emergency exit safety system that can last.

Long life - no matter where

The secret of success of these dampers is hidden inside. Because, whether as self-adjusting or adjustable elements, made of steel or stainless steel: All elements of this family are equipped with state-of-the-art damping technology. Provided with a hardened guide bearing and an integrated hard stop, they provide a long service life even in the most difficult environments. An important advantage for designers is their high energy consumption in a compact design, depending on the version with threads available in sizes M33, M45 and M64. The provider takes over, as in the case described here, the interpretations to offer tailor-made solutions. To ensure that users do not have to compromise on the permissible temperature range, special high and low temperature series have been developed. They allow use at extreme temperatures from -50 ° to 150 ° C.

The Magnum dampers are extremely durable and are probably suitable for more load changes than the operators ever have to put through fire drills or even emergencies to the test. Seen from this point of view and above all in combination with the partnership work, the Dutch clients are also fully satisfied with the hydraulic helpers and are looking forward to the future for the Metro Amsterdam and for all passengers.