The road to les Carroz is close till september (at least !)
if you want to jump in Magland, you can walk to the exit point (1 hour) or use another road (Cluses -> Chatillon -> Les Carroz) but it's a long way ....
Do you know if they are just doing general road maintenance on the road or is it something else? Just trying to get a general idea as to when it will re-open. I may be in Southern Europe from August 29th until September 14th and the Magland area is definitely on my list of places to stay. (I'm familar with most of the jumps there -- just wondering about the road)