For my birthday, Nancy took me on a trip to Jackson Hole.  Part of the trip was a journey in to Yellowstone National park in a snowcoach.  The snowcoaches are modified vehicles to handle to snowy terrain.  They come in two main forms.  One is the tracked vehicle and the other is based on monster truck tires.  The one we took was tracked.  It was a pretty standard van design with four wheel drive but the wheels had been removed and replaced with triangular track arrangements called Mattracks.  These can deal with pretty much any snow.  The only downside is that they are a bit noisy, not too fast and boy do they guzzle fuel.  One our trip we stopped for fuel twice and were pretty low by the time we got back.

We also saw some of the other vehicles out and about.  The monster truck tired vehicles can attain better speeds and efficiency (plus the maintenance is so much lower) but they are not as reliable in dealing with the worst of the conditions.  However, they do seem to be the way that everyone is going.  Our guide told us the tracked vehicles are gradually being replaced.  It should be noted that, after the winter, the tracks are taken off and they revert to normal road use.