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Heritage classified

Key figures

Origin and history

Busseau viaduct is a French steel railway bridge built between December 1863 and December 1864, located in the communes of Ahun, Pionnat and Cressat, Creuse. It is 320 metres long and 57 metres high, overlooking the Creuse River. Although wrongly attributed to Gustave Eiffel, it was designed by engineers Marie Thirion, Wilhelm Nördling and Charles Geoffroy for the Compagnie d'Orléans, with a construction led by Felix Moreaux.

The project was inspired by pioneer metal viaducts such as Grandfey in Switzerland (1857-1862) and Crumlin in Great Britain (1853-1857). The decision to build a metal work rather than a masonry was motivated by a reduced cost of half, as demonstrated by the Fribourg viaduct. Two major challenges were met: to ensure stability in the face of transverse winds by means of internal anchor bars, and to improve aesthetics by avoiding unsightly arching, solved by a test model.

Construction began in January 1864 after ministerial approval in March 1863. The deck was assembled by lancing, an innovative technique where each span was built on the shore and then pushed into place. This method, used for the first time in Europe on the viaduct of Freiburg, allowed a realization in just one year. The total cost was CHF 1 514 989, slightly higher than the estimated CHF 1 453,500.

Inaugurated in December 1864, the viaduct was first used for the Busseau-sur-Creuse–Saint-Sulpice-Laurrière line and then for the branch line to Aubusson. In 1905, a reinforced concrete platform was added, and repairs took place in 1944-1945 after war damage. Ranked a Historic Monument in 1975, there remains a major testimony of 19th century railway engineering, although the Busseau-sur-Creuse–Ussel line closed in September 2025.

The impressive dimensions of the viaduct include a total deck length of 286.50 metres, six spans (four of which are 50 metres), and a maximum height of 56.50 metres. Metal batteries, limited to 30 metres above masonry bases, are based on foundations designed to absorb thermal expansions. The apron, originally planned for two lanes, is only one today.

Wilhelm Nördling, chief engineer, played a key role in the design, building on his experience at Grandfey viaduct. The consortium of builders included Basile Parent, Pierre Schaken, Jules-César Houel and Ferdinand Caillet (future founders of the Compagnie de Fives-Lille), as well as the Establishments Jean-François Cail. The viaduct illustrates the technical innovation of the time, combining economy, rapid construction and bold structural solutions.

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