Aqueduc des voûtes - Thomas Jorion

Hers aqueduct,
a unique structure created by Vauban

Hers aqueduct is one of the many canal aqueducts on the Canal du Midi. This engineering structure was designed by Vauban and built by Antoine de Niquet, and is an impressive technical achievement and a unique heritage site for the canal.

Hers aqueduct

The original route for the Canal du Midi

Pierre-Paul Riquet found quite a simple solution to the issue of crossing a great number of streams and rivers that he was faced with when building the Canal du Midi.

The canal route originally followed a contour line. When two waterways crossed paths, Pierre-Paul Riquet resolved the issue by diverting the waters of streams and rivers into the canal and then providing an outlet further downstream, thanks to a weir. There were no plans to build bridges over the waterways.

In 1685, it was observed that this solution meant the canal silted up very quickly. In addition, the maintenance cost of the weirs was not compensated by boat navigation taxes.

An atypical structure designed by Vauban

To prevent siltation of the Canal du Midi, Louis XIV asked Vauban to come up with some technical improvements. Vauban carried out an inspection in January and February 1686, and as a result, proposed the construction of numerous engineering structures and improvements for the Canal du Midi water supply system. He entrusted this project to his engineer, Antoine de Niquet.

Hers aqueduct was a part of these improvement plans. Thanks to this canal aqueduct, the Canal du Midi could cross the Hers-Mort. It was built by Jean Barrière and Pierre Berquière, master masons from Castelnaudary and Labarthe respectively.

Construction of the Canal du Midi between 1666 and 1694

Remains of Villefranche-de-Lauragais municipal swimming pool

In the 1920s, a swimming pool was created on Hers-Mort river. This pool was located downstream of the aqueduct, and was the very first municipal swimming pool in Villefranche de Lauragais!

Cependant, les activités nautiques emblématiques du site disparaissent progressivement avec l’inauguration du parc municipal des sports de Villefranche-de-Lauragais en 1969.

Les incontournables de Villefranche-de-Lauragais

Modifications in the late 18th century

Have you noticed the two vast stone weirs on either side of the structure? They were designed in 1771 and 1773 to evacuate the excess waters from the Hers river. The Hers aqueduct we can see today is mainly the result of construction work carried out by Jean-Polycarpe Maguès in 1806.

In 1869, major modifications were made to Hers aqueduct by chief engineer, Tardy. The goal was to replace the aqueduct double archway with a single one, to prevent the formation of logjams when water levels were high on the Hers. This work was never completed.

A historic stop on the canal

Unique, safeguarded waterway heritage

Hers aqueduct has been modified over time. Technical improvements made by Vauban's successors helped save this exceptional structure and ensure this waterway transport heritage could be passed on to future generations.

The Hers aqueduct site is an example of the ingenious solutions that were put forward to address specific issues encountered by navigation on the Canal du Midi. In 1998, Hers aqueduct was listed as a Historic Monument.

Recent restoration
of Hers aqueduct

The desire to protect this historic heritage site is still very much alive. Therefore, between 2019 and 2022, a significant restoration project for Hers aqueduct was launched by Voies Navigables de France, in charge of managing the canal.

Restoration work was co-financed by the Occitanie region, the Departmental Council of the Haute-Garonne and individual donations via la 'Fondation du Patrimoine' (heritage foundation). Thanks to the recent restoration, the Hers aqueduct is once again an exceptional heritage site.

Explore Renneville lock

Near Hers aqueduct, you'll find Renneville lock and a mooring point. Don't hesitate to go there on a boat trip!

There is a motorway rest area just 650 m from Hers aqueduct so drivers can make the most of a break from driving to explore this heritage site, and those exploring the canal route can use the services at the rest area.