Above the tracks is what the snow sheds are for, they also protect the tracks from accumulation. When the snow is really piling up, the spreaders and flangers are running almost non-stop, until it ends. That's why the rotaries don't get used much. UP goes years at a time without needing them.
Pentrex, the train video company, used to have one called "The Battle for Donner Pass". It was on VHS. They later combined it with another Donner video and put both on a single DVD. It's a great video, and you ride along with the crew and see the rotaries in action. They show a lot of other winter activities, like shooting down icicles, and blasting ice from flangeways.
I think they kept four sets. You can actually see three of them on Google Earth. Too bad there's no way to see real time.
My wife and I stopped in Roseville back in 2013. Kind of weird seeing a snow plow with a palm tree in the background.
