It is being suggested that the Tunnel Du Chambon may be open to cyclists every sunday, during the current closures, so that cycling tourism can get from Le Bourg d’Oisans to La Grave and the Col du Lautaret. However the report suggests that this will only be from 10am until 12pm. I guess this will have to be a fast ride up and back, or perhaps do the Marmotte route in reverse.
If this is the case, it would suggest that it might also be possibly for the tunnel to be opened to cycling traffic for events such as the Marmotte and the Tour de France (should repairs be delayed), although no suggestion has been made.
More information to follow as it come to us.