Montech's unique water slope

In Montech, located in the Tarn-et-Garonne region of France, a special water slope allowed boats to rise 13.30 meters without using locks. This system, developed by engineer Jean Aubert, was a groundbreaking innovation when it was first used in 1974.

A world-first engineering feat

The Montech water slope was the first of its kind globally. It lifted boats by moving a section of water 125 meters uphill using a shield pushed by two diesel locomotives. This method avoided the need for traditional locks and was in operation from 1974 to 2009.

Modernizing the Two Seas Canal

The Two Seas Canal, which connects the Atlantic Ocean to the Mediterranean Sea, required modernization in 1969. The lateral canal to the Garonne, a key part of the route, was upgraded to accommodate larger barges. This involved extending 53 locks to 40 meters in length.

The challenge of multiple locks

In Montech, five locks—Montech, Les Peyrets, Pellaborie, Escudiès, and Pommiès—are clustered closely together to manage the elevation change. Each lock must be filled and emptied in sequence, adding time to the process. This repetitive procedure significantly increased waiting times for boats passing through.

A new approach to water movement

Jean Aubert proposed a radical alternative to traditional lock systems. Instead of raising water in basins, his design moved water itself along a slope, with the boat resting on top. This innovative system was constructed starting in 1971 and became operational in 1974.

The structure of the water slope

The water slope consists of a U-shaped concrete ditch about 440 meters long and 6 meters wide, inclined at a 3 percent grade. It is closed at the top by a gate. The ditch’s bottom rises gradually, while the water surface remains level. This design allows a section of water to be pushed uphill by a shield.

Operation of the system

Two diesel-electric locomotives, connected to each other, push the shield along the ditch. The shield moves a 125-meter section of water, allowing the boat to ascend without leaving the water. The locomotives move at the same speed to prevent tilting the shield in the narrow ditch.

The end of operation

The water slope operated for 35 years, from 1974 to 2009. In May 2009, a fire damaged one of the engines, and repairs were deemed too costly. Since November 6, 2009, the system has been out of service, and boats now use the five locks again, adding about 45 minutes to their journey.

A site for tourism

Today, the Montech water slope is a tourist attraction. The Tarn-et-Garonne Department promotes the site, offering guided tours of the ditch, shield, and locomotives. Visitors can explore the engineering marvel that once revolutionized canal navigation.