Timeline

Heritage classified

Key figures

Origin and history

The Gier Waterway, 86 km long, is one of four ancient aqueducts serving Lugdunum (Lyon). It draws its waters from the river Gier, tributary of the Rhône, and is known to be best preserved. Its construction, originally attributed to Claude or Auguste, was dated from the reign of Trajan (ca. 110 AD) thanks to dendrochronological analyses on the wooden formwork of the Beaunant Siphon Bridge. However, it may have been completed under Hadrian.

The Merdanson Bridge section, located in Orlienas (Rhône), has been one of the remains protected as historical monuments since 2021. This section illustrates Roman construction techniques, combining covered trenches, tunnels and water bridges. Aqueduct traversed 22 communes, with spectacular siphons such as that of the Yzeron, 2.6 km long and equipped with lead pipes resistant to 13 bar pressure.

In the 16th century, extensive studies were carried out by local scholars such as Pierre Sala and Symphorien Champier. In the 19th century, archaeologists such as Paul de Gasparin and Germain de Montauzan mapped its layout and analysed its technical characteristics. Recent restorations, such as those carried out in Chaponost in 2009-2010, have preserved its masonry using authentic Roman techniques.

Two protective pillars, the Pierre de Chagnon (1887) and the Pierre du Rieu (1996), attest to ancient regulations prohibiting cultivation or construction in the vicinity of the aqueduct to ensure its sustainability. These inscriptions, dated from the Hadrian era, contain Austéan legislation aimed at protecting hydraulic infrastructure.

The Pont du Merdanson, classified in 2021, today retains only its last arch and a few scattered blocks. This site is part of a broader set, including reservoirs, siphons and tunnels, testifying to Roman engineering. The Gier water supply, with an estimated 15,000 m3/day of flow, was vital for ancient Lyon water supply.

In 2018, the pipeline benefited from the Heritage Lotto, stressing its historical importance and the need for its preservation. The remains, although partially destroyed, offer a unique overview of Roman construction techniques and their adaptation to the relief of the Lyon plateau.

External links