The tunnel is a vital link between the northern and southern French Alps. It allows visitors to reach Alpe d’Huez and Les Deux Alpes from Briançon or Italy, as well as connecting La Grave and Serre Chevalier to Grenoble and Lyon airports.
The road closed in April 2015 following significant movements being detected in the rock the tunnel was drilled through. The closure meant many people were unable to travel to work and children could not attend school. Initially, people had to walk for around 40 minutes on mountain paths to bypass the tunnel, and arrange for transport to meet them on the other side. Within a few weeks, a water taxi service had been put in place on Lac Chambon, the lake that the tunnel runs alongside.