I don't recall if it is a state or federal level highway so it is open to anyone to use.  There should be restrictions on it however prohibiting commercial traffic on weekends or at the very least if your rig is over so many feet you have to have a lead vehicle to forwarn oncoming traffic.

That being said accidents are still going to happen. A couple of seconds difference in rounding one of the curves on the way down would have made us hood ornaments on an old full sized Ford sedan that was being driven WAY outside its handling envelope versus watching it use ALL of the road in the rear view mirror behind us.

Well all I can say is I think we made great timing and glad I slowed down when returning down the hill.   I would of been faster after seeing the photos of trucks made me aware of issues.