On September 2, 2015 Le Parisien published an article saying that a a diversion tunnel will be dug above the Chambon Lake to bypass the landslide area that has led to the closure of the Grenoble-Briançon road.
A statement by the Isère department declared that a 990m tunnel would be the solution.
The RD1091 is a major traffic route between Grenoble and Briançon and has been closed to traffic since April 10 with very serious consequences for residents, many living from the tourism generated by passing traffic. The roof of the Chambon tunnel is threatened by a landslide. Part of the mountain has already collapsed into the lake below and the remaining rocks are unstable.
The solution proposed by by the Isère department is to dig into the slope to overcome the slip region and cut out that part of the RD 1091. The operation is however very expensive, estimated between 20 and 25 million euros.
During a visit to Mont-de-Lans (Isère) by the Prime Minister in late July the idea of a 200m diversion tunnel was discussed at a cost of 10 to 12 million euros. During this visit, Manuel Valls had promised financial support from the state for the reopening of the road. The goal is to open the new tunnel to traffic for the winter season 2016/2017.