Garabit Viaduct

The observation tower in the center of Paris or the supporting structure of the Statue of Liberty are just charming byproducts of the French engineer Gustave Eiffel, who executed dozens of unique transportation constructions around the world. Among the boldest structures of his time is the Garabit railway viaduct in the French region of Auvergne, which was completed five years before the Eiffel Tower. The Garabit viaduct is located on the Paris-Béziers railway line near the town of Ruynes-en-Margeride, where it spans the Truyère River and overcomes a valley depth of 122 meters.
Eiffel's office was invited to the project, as it already had similar experience with the Maria Pia steel bridge over the Douro River (completed in 1877, 42 m high, 353 m long), on which Eiffel collaborated with Théophile Seyrig. A young Swiss engineer, Maurice Koechlin, who had just joined Eiffel's company, was involved in the Garabit viaduct project. The fact that Eiffel made the right choice is evidenced by the fact that when he retired in 1893, he entrusted the leadership of the office Eiffel et Cie to Maurice Koechlin, who led the practice until 1940.
Given the high wind load values, Eiffel opted for a truss construction. The costly construction saw 500 workers rotate between 1882 and 1884. The first load test took place in August 1888. The main supporting parabolic arch has a span of 165 m, and the total length of the bridge is 565 m. The height of the bridge pier is 80 m. The weight of the masonry is 3,249 tons, and the volume of the masonry part is 18,647 cubic meters. The weight of the iron used is 3,326 tons. The bridge was painted pink, using 38 tons of paint. At the time, the Garabit viaduct was the largest (and third highest) bridge in the world. In 1959, a dam, Grandval, was built beneath the bridge. In 1965, the bridge was listed among the historical monuments of France.