The tunnel, which carries the D1091, was partially reopened at the end of last year following a landslide in 2015 along the mountain through with the bore is located. Local media report that from the end of this month, the tunnel will be closed again for the final phase of lining work. The road connects Bourg d’Oisans and the Col du Lautaret and Col du Galibier.
The D1091 follows the edge of Chambon Reservoir which was built in 1935. The road previously ran in the valley but had to be relocated to the reservoir’s edge and was constructed at the same time as the reservoir.
To help accommodate traffic during tunnel closure, the central government paid around €24.4 million diversions including a 5.3km route secours - emergency road - along the opposite edge of the reservoir. However, the RS is for passenger vehicles and restricted to trucks of 3.5 tonnes.