Schlaichturm Tower in Weil at Rhine river

Saturday, 02 April 2022 07:05
Written by Portal Editor

Our research during our visit to Weil am Rhein also revealed that there has been an interesting viewing tower in the park area on the border of Weil and Basel since the state garden show "Grün 99", which understandably immediately aroused our interest.

The observation tower is officially called the "Schlaichturm", but it is also popularly known as the "Green 99" observation tower in reference to the State Garden Show. From its platform, the Schleichturm offers an overview of the entire open-air area of the Mattfeld and a great view towards Basel and the border triangle, which we were to enjoy ourselves a little later.

Stair tower also to overcome the height difference

The Schleichturm stands on the northern edge of the Dreiländergarten, overcoming a 16-meter-high jump in the terrain between the park and the hamlet of Leopoldshöhe housing estate. From the north, you can reach the stair tower via Marktstraße and Hebeplatz via a pedestrian bridge, from which two stairs branch off to the Weil-Gartenstadt train station on the Weil am Rhein – Lörrach railway line. The bridge spans the railway line in a slight arc and the B 317, which runs parallel to it in this section. To the south on the park side, from where we got to the Schleichturm, the stair tower gives access to the leisure facilities of the Dreiländerpark.

The engineering office Schlaich Bergermann und Partner, which designed and calculated the tower, gave it its name. The filigree tower structure, which is stabilized by pre-tensioned cables, shows structural similarities to the observation tower on the Killesberg in Stuttgart, which was built two years later and was designed by the same engineering office.

The need for a stair tower to overcome the terrain profile results from the comparatively large height. Including the track's light profile, the difference to be negotiated is 22 meters, which would have required a ramp length of 370 meters with a maximum incline of 6% for disabled people. A ramp of this length would no longer have been justifiable in terms of landscape compatibility.

Construction of steel masts and stay cables

From the platform north of the tower, a level 2.50 meter wide and 45-meter-long footbridge leads 16 meters above the main road to a circular platform with a diameter of 10 meters. Above this, two steps lead to the somewhat wider overhanging viewing platform. From this platform at a height of 20 meters you have a view of the park area, the lower Wiesental, the mountain ridge of St. Chrischona and neighboring Basel.

The tower with its two platforms is crossed in the middle by a steel mast. The top platform is held up by twelve stay cables that branch off radially from the masthead. In the direction of the jetty, two additional cables carry the jet loads. Two spiral staircases, each around 65 meters long and 1.20 meters wide, lead from the lower platform to the Dreiländerpark. One is for going up, the other for going down. The spiral staircases are additionally stabilized by vertical and diagonal cables. The inner vertical cables are attached directly to the upper suspensions, the outer ones are connected to the cantilever beam of the upper platform. Spotlights are attached to the lower and upper end of the mast, which immerse the tower in indirect light at night via fan-shaped mirrors, so that it can also be used by passers-by at night, and which take up the lines of the cables in terms of design.

Please read as well:

Dreiländerbrücke between Weil am Rhein and Huningue

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