Timeline

Heritage classified

Key figures

Origin and history

The Royal Bridge of Chamousset, located in the Savoy department in the Auvergne-Rhône-Alpes region, is associated with the Gelon hydraulic tunnel, a major 19th-century structure. Watered in 1854, this 125-metre-long tunnel was dug to solve the flooding problems caused by the Gelon, a tributary of the Arc, after its containment between 1830 and 1841. The work, led by engineer Joseph Mosca, lasted a decade due to technical difficulties, including the instability of the moraine, requiring a two-chamber design instead of a single one.

Before the tunnel was built, the Gelon floods, blocked by the dykes of the Arc, regularly transformed the Chamousset and Bourgneuf lands into marshes, destroying crops and causing epidemics of fever. In 1848 Léon Brunier denounced the catastrophic situation, where the fields had become uncultivated and the population decimated. This dramatic context accelerated the project of deviation from the Gelon to the Isère via the tunnel, despite delays and changes of entrepreneurs.

The tunnel, listed as a historical monument in 1986 with the Royal Bridge, illustrates 19th century hydraulic engineering. Built in stone masonry and concrete, it allows the Gelon to cross the hill of Chamousset before reaching Isère. Nearby, the Saint-Maurice church, also classified, overlooks this hydraulic system, witness to the human adaptations to the geographical and climatic challenges of the Savoy.

The materials used, such as the stones of Reverdel's quarry or the concrete vaults, reflect the techniques of the era. The project, albeit late, settled the floods and improved local living conditions. Today, the Royal Bridge and the tunnel remain symbols of Savoyard industrial and architectural heritage, protected for their historical and technical value.

External links