Zähringer Bridge
Coordinates: 46 ° 48 '23 " N , 7 ° 9' 59" E ; CH1903: five hundred seventy-nine thousand two hundred seventeen / 183938
| Zähringer Bridge | ||
|---|---|---|
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| use | Road bridge | |
| Crossing of | Saane | |
| place | Freiburg in Üechtland | |
| construction | Arch bridge | |
| overall length | 246.26 m | |
| Longest span | 34 m | |
| height | 46 m | |
| start of building | 1922 | |
| opening | 1924 | |
| location | ||
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The Zähringerbrücke is a road bridge over the Saane in Friborg in Switzerland . The current structure was erected in 1924 on the site of a suspension bridge called Grand Pont in French , which, when it was completed in 1834, had the longest span in the world at 273 m.
Stone arch bridge from 1924
The tender for the renovation of the Grand Pont provided for the conversion of the existing suspension bridge or the construction of a massive arch bridge . A commission of experts evaluated the various projects of the construction companies. Since a height of at least 3 m was considered necessary for the reinforcement girder of a new suspension bridge and the Saane valley is only 50 m deep, it was decided not to use the old construction again for aesthetic reasons. The commission voted for a massive viaduct with a series of openings of equal width.
The 246 m long viaduct from concrete has 7/2 circular arched openings with internal diameters of 30 m. The pillars are 4.0 m long at their heads; the width of the deck with sidewalks and bicycle lanes on both sides is 11.5 m. In addition, a 3.5 m wide bridge with three segment arches was built at the bottom of the Saane.
In April 1922, the Züblin company was commissioned to build the new bridge, which was built in the axis of the old structure. The foundation of the river pillar was made with a caisson . The inauguration of the bridge took place on Sunday, November 16, 1924.
Since the opening of the Poya Bridge on October 12, 2014, the Zähringer Bridge has been closed to private car traffic.
Suspension bridge from 1834
| Grand Pont | |
|---|---|
 |
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| overall length | 273 m |
| width | 7.5 m |
| Arrow height | 19.28 m |
| building-costs | 200,000 Swiss Francs |
| start of building | 1832 |
| opening | 1834 |
| Status | canceled |
| planner | Joseph Chaley |
| closure | 1923 |
The first Zähringer Bridge, called Grand Pont in French , was built between 1832 and 1834 to connect Freiburg's old town with the right bank of the Saane.
At the beginning of the 19th century, Freiburg tried to improve its connections to the surrounding area, mainly to Bern. Several projects were evaluated, such as that of Guillaume-Henri Dufour , who proposed a two-span bridge with trussed girders and a 45 m high central pier for 320,000 Swiss francs , or that of Giulio Pocobelli from Ticino , who proposed a stone arch bridge for 640 ' 000 francs suggested.
The design by the French engineer Joseph Chaley that was carried out was the cheapest at 200,000 francs, because his suspension bridge spanned the Saane with a span of 273 m without a central pillar, which was the longest span in the world when it was completed. It was only replaced in 1849 by the Wheeling Suspension Bridge with 308 m as the longest suspension bridge.
A wooden carriageway construction with a 4.9 m wide carriageway and 0.88 m wide sidewalks on both sides hung from the bridge's supporting cables. The stiffening beams were 1.05 m high and designed as handrails, which gave the bridge the appearance of a footbridge. Two suspension cables were arranged on each side, each consisting of 1056 individual wires with a diameter of 3 mm each. The arrow height was only 19.28 m. For assembly, the cables were laid out in the valley and then pulled upwards. The catwalk , which was not yet known at the time, was used for the first time in the construction of suspension bridges. Twelve guns with 50 horses and 300 people loaded the structure on a trial basis before the traffic handover.
In 1881 the bridge was reinforced with two additional suspension cables. Corrosion on the suspension cables and the insufficient rigidity of the wooden carriageway construction finally led to a replacement building in the early 1920s.
literature
- Arthur Rohn : The Zähringer Bridge in Freiburg, the new building instead of the large suspension bridge . In: Schweizerische Bauzeitung , Volume 81, 1923, ISSN 0036-7524 , pp. 189–194.
Web links
- Grand Pont Suspendu. In: Structurae
- Pont de Zaehringen. In: Structurae
- Le pont de Zaehringen ( Memento from February 11, 2009 in the Internet Archive )
Individual evidence
- ^ Harteveld Rare Books Ltd .: Illustrated Books. Retrieved January 19, 2014 : "Ce pont projetté par Mr. Dufour de Genève, Colonel fédérale du Génie, a en longeur 840 pieds de Berne et la pile a hors de terre, 154 pieds en hauteur."
- ^ Freiburg: a city in the 19th and 20th centuries . Saint-Paul, 2007, ISBN 978-2-88355-108-4 , pp. 115–.
- ↑ Sven Ewert: Bridges - The development of spans and systems . Ernst & Sohn, Berlin 2003, ISBN 3-433-01612-7 , pp. 58 .
- ↑ Richard Scott: In the wake of Tacoma, suspension bridges and the quest for aerodynamic stability . ASCE Press, Reston, Va. 2001, ISBN 0-7844-0542-5 , p. 7
- ^ Josef Brunner: Contribution to the historical development of bridge building in Switzerland . Doctoral thesis, Bern 1924, p. 48