The construction of the Neufosse canal linking the Aa and Lys rivers at Aire-sur-la-Lys began in 1758. With the development of industry in the 19th century, its economic role took precedence over its initial military purpose.
The main obstacle in its construction was crossing the south bank of the Aa valley in the place known as “Les Fontinettes” in Arques. To compensate for the 13.13 meter difference in water level, the military engineers constructed a succession of seven locks. As traffic on the canal increased, the barges had to wait increasingly longer and longer to cross the locks. In the 1880s, the construction of a hydraulic lift offered a solution to this problem. The English engineer Edwin Clark worked with Bertin, a French engineer, on the project.
The work entailed building a structure made up of three brick towers, which guided two mobile metal chambers, driven by 2 meter diameter pistons. Gantry cranes upstream and downstream of this structure opened the gates to allow the barges (Freycinet type 38.5 x 5 meters) to enter and exit the lift. The metal chambers were sealed by means of a rubber air cushion. At the highest point, two railway bridges were built over the canal. The manoeuvres required six men, took only 20 minutes, and were controlled from the top of the central tower.
With new European canal gauges, the lift became too small and had to be closed in 1967. This construction is the only one of its kind in France. It became a listed structure in 2014 and will undergo restoration in 2016.