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Origin and history

The Saint-Roch Bridge, also known as the Lavaur Bridge, is an 18th-century masonry structure crossing the Agout River in Lavaur, Occitanie. With a range of 48.75 metres, it was, after the collapse of the Old Brioude Bridge in 1822, the largest masonry bridge in the world until the construction of the Chester Bridge (England) in 1833. Its unique arch, designed in light basket handle, and its parapets extended by esplanades planted with cedars give it an exceptional monumental character. The floor of the pedestrian crossing uses the traditional calade technique, typical of southern constructions.

Designed by engineer Joseph-Marie de Saget (1725–82), Director of Public Works of Languedoc, the bridge was built between 1777 and 1785, despite interruptions due to the floods of the Agout. De Saget directs the works until his death in 1782, which occurred shortly after the decimation of the arch. His brother, François de Saget, took over. The entrepreneurs Chauvet (Montpellier) then Grimaud (Monesties) and Albouy (Saint-Papoul) succeeded each other to complete the work, delivered to traffic in 1791. The initial project provided for Languedoc coats of arms on the harps, but these were never realized or disappeared.

The bridge replaces two historic ferries on the Agout, used for connections to Castres and Albi. Its location, below the gardens of the bishopric and opposite the cemetery Saint-Roch, fits into a wider urban development, including straight avenues and symmetrical round towers strengthening the abutments. In 1840, cracks on the hanger were repaired by engineer Béqué. The bridge has been listed as a historical monument since 3 March 1960 and is now part of the Tarn department.

Prior to its construction, local communications depended on ferries through the Agout, such as those in the port of Taïx (to Gaillac) and the port of Lavaur (to Graulhet). The site, which began in 1773 with the laying of the first stone by the bishops of Narbonne and Lavaur, was marked by technical challenges related to the stability of the slopes and the unprecedented reach of the arch. The bridge was named after a 15th-century chapel, destroyed to enable it to be built.

The Lavaur Bridge illustrates the architectural audacity of the 18th century engineers, combining technical innovation (low vault) and classical aesthetics (mouldings, curved parapets). Its record range, although surpassed in the 19th century by railway bridges, remains a major testimony of the civil engineering of Ancien Régime in Occitanie. The presence of a tannery and then a bath establishment at its foot until 1875 underscores its integration into local economic life.

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