After the Grand Pont, the Barre Tunnel is the other leading engineering structure in the urban belt designed by the local engineer Adrien Pichard in the 1830s. It was dug by the engineer Victor Dériaz and the architect Georges Krieg between 1851 and 1855, and was one of the last elements in the belt to be completed. It connects the deep valleys of the Flon and Louve rivers at the point where the two watercourses run closely alongside each other and narrow at the “Barre” before going around the hill in the city. The water flows that can be seen under the vaulting bear witness to the very aquiferous nature of the soil, which made the building work very difficult.
The tunnel, 56 metres long, is clad entirely in dressed stone. The semi-circular entrances are over 11 metres tall under the vaulting and are framed with buttresses. They are extended on each side by powerful supporting walls, curved wings which ensure the integration of the structure in the urban framework. At the summit the parapets follow a slight curve, showing the care taken over the architecture of the project.
The drilling of the Barre Tunnel began the urbanisation of the valley of the Louve above the Riponne, especially with the construction of workmen’s houses surrounding the Tunnel square to the East (1862-63).
