Viaduc de Longeray
Coordinates: 46 ° 6 ′ 48 ″ N , 5 ° 53 ′ 21 ″ E
| Viaduc de Longeray | ||
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| use | Railway bridge | |
| Crossing of | Rhone | |
| place | Léaz , Ain | |
| construction | Reinforced concrete bridge | |
| overall length | 280 m | |
| Longest span | 69 m | |
| start of building | 1875/1941 | |
| completion | 1880/1943 | |
| location | ||
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The Viaduc de Longeray is a railway bridge over the Rhone between the communes of Léaz , Département Ain and Clarafond-Arcine , Haute-Savoie , in France , around 20 km as the crow flies south-west of Geneva .
It leads the single-track railway branching off the Lyon – Genève railway line in Léaz-Longeray to Annemasse and Évian-les-Bains across the narrow, deeply cut valley of the Défilé de l'Écluse , in which the Rhône breaks through the Jura .
Truss Bridge (1880)
As part of the construction of the railway line to Annemasse, the first Viaduc de Longeray was built between 1875 and 1879 or 1880, which was also known as the Viaduc du Credo . According to the plans of the engineers Moris and Ruelle, the company Joret et Compagnie built a wrought-iron , parallel- chorded truss bridge with three masonry pillars, some over 60 m high, and four openings with spans of 48 + 58 + 69 + 54 m. The eastern slope was bridged by a brick viaduct with 5 round arches, each 15 m wide, which led the curve to the further route running along the slope. The structure was more than 300 m long.
The bridge seems to have survived the 60 years up to the Second World War without major problems. On June 19, 1940, three days before the Compiègne armistice , a French engineering unit blew up the left of the two central pillars to prevent the German army from crossing the Rhone. The superstructure of the bridge collapsed completely.
The French railway SNCF , interested in resuming traffic , which was still able to act relatively independently under the German occupation, decided at the end of 1940 to rebuild the bridge. However, the necessary steel was not available during the war. It was therefore decided to start a reinforced concrete project.
Concrete Arch Bridge (1943)
Although a traditional girder bridge made of reinforced concrete is usually significantly heavier than a steel structure, the new building had to adapt to the old pillar foundations and the viaduct still existing on the eastern slope for reasons of time and costs. The bridge therefore had to be made as light as possible.
The three central openings therefore have the same span as the old bridge. The pillars are very slim and have a clearly visible suit , so a tapering of the cross section up. Between them, parabolic arches are arranged, which are also supported on the pillar foundations and on the apex of which small supports distribute the loads of the carriageway girders as far as possible. Both the pillars and the parabolic arches have multi-cell hollow cross-sections and thin walls. The deck girder is also a two-cell box girder with a height of 3 m. The carriageway joins the old viaduct on the eastern slope. Instead of the earlier fourth opening on the western slope, a concrete viaduct was built there, the three arches of which are also 15 m wide.
The falsework for the parabolic arch over the river was made in two halves from sickle-shaped, wooden shapes that were first made on the base of the pillars in an almost vertical position and then lowered towards the center of the arch. This procedure was used here for the first time and was discussed a lot afterwards.
At the end of 1940, the SNCF and the Société des Entreprises Limousin, commissioned with the construction, completed the planning work. The actual construction work began in early 1941. At the end of July and early August 1943, the building was opened to traffic.
The bridge is regularly used by the TER Rhône-Alpes trains between Bellegarde-sur-Valserine and Évian-les-Bains . At the weekend, a TGV service between Paris Gare de Lyon and Évian-les-Bains also crosses the bridge.
Web links
Individual evidence
- ↑ a b c d Ancien viaduc ferroviaire de Longeray, dit viaduc du Credo (détruit) on Patrimoine de Rhône-Alpes
- ^ The company Joret et Cie. had recently built the Pont de Sully in Paris.
- ↑ The dimensions vary from source to source, sometimes even within official documents.
- ↑ a b c Viaduc ferroviaire de Longeray on the Patrimoine de Rhône-Alpes
- ^ Marcel Prade: Ponts & Viaducs au XIXe Siècle . Brissaud, Poitiers 1988, ISBN 2-902170-59-9 , p. 283
- ↑ SNCF timetable information