A major landslide risk has forced the closure of the tunnel du Chambon on the popular cycling route from Le Bourg d’Oisans to the Col du Lautaret and the Col du Glandon. Experts are expecting a minimum of three weeks closure, while works are underway. Some sources expect these closures to be significantly longer. Obvioulsy there are major concerns for local businesses and cycling tourism in the area, since this is on the route for La Marmotte in early July and the the Tour de France in late July.
Apparently the 750 meter long tunnel which has been in operation since 1935 has developed a crack measuring 60 meters, suggesting a rapid increase in the usual rate of geological movement. Overnight work was due to start on the tunnel, until the discovery of the crack forced the total closure of the road.
The tunnel is on the main route between Grenoble and Briancon and on into Italy. Alternate route to reach Briancon will be either on the south side of the Ecrins National Park, via Gap, or via the Maurienne valley and the tunnel du Frejus.
Experts are due to meet in the coming days to agree a more accurate time of the works and the eventual re opening.