|This article needs additional citations for verification. (February 2012)|
|Total length||565 (1,854 ft|
|Longest span||165 m (541 ft)|
|Construction cost||3,100,000 francs|
The Garabit Viaduct (Viaduc de Garabit in French) is a railway arch bridge spanning the River Truyère near Ruynes-en-Margeride (Fr), Cantal, France, in the mountainous Massif Central region. The bridge was constructed between 1882 and 1884 by Gustave Eiffel, with structural engineering by Maurice Koechlin, and was opened in 1885. It is 565 m (1,854 ft) in length and has a principal arch of 165 m (541 ft) span.
By the end of the 1870s Eiffel & Cie, the company formed by Gustave Eiffel in partnership with Theophile Seyrig, had an established position among the leading French engineering companies. Between 1875 and 1877 the company had built the Maria Pia Bridge over the Douro at Porto, and when it was proposed to construct a railway between Marvejols and Neussargues in the Cantal department the work of constructing a viaduct to cross the River Truyère was given to Eiffel without the usual process of competitive tendering at the recommendation of the engineers of the state Highways Department since the technical problems involved were similar to those of the Maria Pia Bridge; indeed, it was Eiffel & Cie's success with this project that had led to the proposal for a viaduct at Garabit.
Bridge design and construction
The project was demanding, with a line 120 metres (400 ft) over the River Truyère. Boyer believed this would be considerably less expensive than taking the railway line around or down through the valley. To resist the wind, Eiffel instantly discarded the principle of solid beam construction, thinking that “it would be very heavy and the beams would rattle in the wind”. Instead, he adopted the concept of trusses or “a series of open triangles” to assuage wind force that “would blow right through them”. Truss work also provides stability when loads are applied through the theory of tension and compression that states force is exerted on the diagonal and vertical segments causing them to resist one another. Eiffel also improved upon his Douro design, adopting the same two-hinged crescent-arch form but employing an arch visually separated from the thin horizontal girder. The Garabit Viaduct’s arches were engineered to have support hinges, allowing the crescent shape to widen. This method both simplified calculations and improved resistance to wind loads.
When it opened with a single track in November 1885, the Garabit Viaduct was 565 m (1,854 ft) long and weighed 3587 tons. Even more impressive was the actual deflection, which was measured at 8 millimetres, a figure precisely anticipated by Eiffel’s calculations. The bridge was also, when built, the highest in the world. The overall project cost was 3,100,000 francs. Until 11 September 2009, only one regular passenger train per day in each direction used to pass over the viaduct - a Corail route from Clermont-Ferrand to Béziers. On that date, the viaduct was closed as cracks were discovered in one of the foundation piles. It reopened one month later after a safety inspection and was in service with a speed limit of 10 km/h (6 mph) for all traffic.
On June 15 2011, the Garabit closed for extensive workand reopened on December 15 2011. During the works, the train from Béziers to Clermont-Ferrand terminates at St Chély d'Apcher and a bus continues to Clermont-Ferrand. There is an excellent view of the Garabit viaduct from the bus.
Garabit Viaduct in fiction
The Garabit Viaduct was used to represent the condemned "Cassandra Crossing" bridge in the 1976 film The Cassandra Crossing. In the film the Cassandra Crossing has been unused and derelict for 30 or 40 years and is considered dangerous, to the extent that people living nearby moved away fearing it could collapse.
In 1964, French director Henri-Georges Clouzot shot The Inferno (L'Enfer) starring Serge Reggiani and Romy Schneider at the nearby Hotel Garabit (renamed Hotel du Lac for the movie) and on the lake. The film was never completed after disputes between Clouzot and key actors and crew and Clouzot himself suffering a heart attack.
Added pressure came from a deadline after which an electricity company planned to drain the lake to generate power at a nearby dam, also used as a backdrop for the stillborn movie.
The saga was covered in a documentary screened in June 2010 by Sky Arts 2 in the UK.
- Billington, David P. The Tower and the Bridge: The New Art of Structural Engineering. Princeton, New Jersey: Princeton University Press, 1983. ISBN 978-0-691-02393-9.
- Harvie, David I. Eiffel: The Genius Who Reinvented Himself. Stroud, Gloucestershire: Sutton, 2006 ISBN 0-7509-3309-7
- Loyrette, Henri. Gustave Eiffel. New York: Rizzoli,1985 ISBN 0-8478-0631-6
- Garabit Viaduct at Structurae
- Garabit Viaduct on bridge-info.org
- PBS Building Big series databank entry for Garabit Viaduct
- The Cassandra Crossing at the Internet Movie Database