Opens Feb 1st, will generally stay open until the end of March. May close a little early if the weather dictates, or the loads have all been delivered. May close later if the weather allows and there are more loads yet to haul. 2006 we had to shut down early because of the weather (can't remember the exact date), and I've never known the road to be open past April 5th or 6th. A regular season would be 60 days, +/- 10 days.
Ride Report: Canada North to South 2008 here
Drive Report: Ice Road Trucking 2005-2011 here