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Civil engineering - works of art

From le Malpas to the circular lock in Agde

To build his dream, Pierre-Paul Riquet employed the most ingenious concepts of his time with great daring and intuition. On the Hérault route, between Agde and Capestang, several of his structures are still in use, some in their original form. The breakthrough at Malpas (1679-1680) near the village of Colombiers bears its name well - Malpas means "wrong way"! Dug through the rock, the  river tunnel is 173 m long, 8.5 m wide and 6 metres high with a towpath on the left bank  . Today three tunnels cross each other here: the Canal du Midi is the highest, and the tidal basin relief tunnel is the lowest, with the Montady railway tunnel passing in between, creating a spectacular tangle of technology!


The canal locks of Fonseranes


At the foot of Béziers, the Fonseranes  locks are certainly   the most spectacular sight on the Canal du Midi. Originally composed of nine locks in a row, the  series of eight basins in a staircase is a unique achievement in the history of river transport. Over a length of 300 m, a drop of 21.5 m is achieved. Today, only 7 locks are still in service.


The Fonseranes water slope

Replacing locks with a water slope is common on canals in the North. In Fonseranes, the idea came too late forcommercial traffic which was already all but finished forever when the water slope was abandoned before completion in 1984. It was hoped that this highly expensive project would accelerate the transport of goods, avoiding the slow-passage of the 9-locks. Today, tourists and sailors crossing Fonseranes look on amazed at the gigantic useless machine, a strange modern form which the old-but-reliable locks of quietly mock!  

A water slope? A barge sails into a basin of water, which is transported on a motorized wheel-mounted engine, either upstream or downstream releaseing the boat on arrival at the higher or lower level.


The canal bridge


On arriving at Béziers, the Royal Canal in Beziers runs right into the river Orb. Locks were put in place to connect the two, but the complex system devised by Riquet, working around regular fluctuations river floods, often and causing the sinking of boats without keels, was replaced in 1858 by the canal bridge. Since then, river barges cross the canal bridge, at a height of 12 m. Galleries which run through the interior, can still be visited. With a width of 28 m, the canal bridge covers a distance of 240 m. The canal was diverted at the seventh  Fonseranes lock to accommodate the bridge. The new route bypassed the old Port of Notre Dame which was replaced in the early twentieth century by the Port Neuf (new port).


the  Roque-Haute channel

Situated between  Portiragnes  and Vias, the extinct volcano of Roque-Haute provided  the basalt stones that were used in the construction of most buildings in the area. A connecting channel connected the canal to the quarry. Today a nature reserve, the site retains the traces of this stone extraction that contributed so much to the local economy.


Libron passage

This work dates from 1858 and replaced the old system designed by Riquet. Urban Magu, chief engineer of the Canal and also designer of the Béziers Canal Bridge, completed this work. Four adjoining chambers allow water to flow freely from the Libron without diversing its silt into the canal. The machinery is impressive - a tangle of metal structures, pin wheels and porticos, worthy of Jules Verne.


the Circular lock of Agde

Built in 1679-1680, the round lock at Agde  permits a 3-way connection leading to the city and the Agde channel. The round central pool was enlarged for the passage of large barges, but retains its unique charm.

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