The NP grade down the east slope of Lookout Pass is totally open to vehicles from the summit (I-90 Exit 0) down to where the grade crosses the road which leads up to the Route of the Hiawatha trail. Check a good map or inquire at the Lookout Pass ski/bike shop to make sure you start down the railroad grade and not the old highway grade. The section through Borax tunnel might be deeply rutted and muddy. Sections of both the NP and MILW grades the rest of the way east toward St. Regis are open to vehicles in places, but some bridges are currently blocked. Plans are to extend the Route of the Hiawatha to St. Regis and beyond.

I haven't driven the NP grade down the west side of Lookout yet, but everything I've read indicates it's open to vehicles, and I have some friends who have taken large groups of ATVs up and down that side with no problems.

Yes, the S-shaped trestle was replaced by a switchback, in 1963.