Acceleration of a landslide in the French Alps that closed a road tunnel in April could be replaced with a new temporary road on the other side of Lake Chambon.
Speaking at a local authority plenary session regional president Jean-Pierre Barbier said that the council was in favour of constructing a €5M alternative route on the other side of the lake, in addition to the €14M of Chambon Tunnel repairs.
The DR 1091 route in the Isère Department was closed in April because of concerns over crown failure in the tunnel and boats have been ferrying passengers past the tunnel closure since.
Closure of the tunnel will mean that the 2015 Tour de France will not pass over the Col du Galibier this year.
Initially work was planned to repair the tunnel in order for it to be reopened ahead of the event but Barbier said that the landslide that triggered the crown failure had started to accelerate and he voiced doubts about whether the tunnel can be reopened in the short term. “The new thing is the acceleration of the landslide,” he said. Barbier estimated that the landslide mass weighs 250,000t and has a volume of 100,000m3, which is now advancing at 100mm per day.
Barbier said that the new road would create an alternative route. “Companies have been invited [to tender] and the work can begin very quickly,” he said. “Although the plan currently lacks authorisation, sometimes the state much launch such projects without the normal preliminary steps in exceptional circumstances.”
Local authorities are also considering draining Lake Chambon as a precaution in the event of catastrophic failure of the landslide.