Crews have started clearing Yellowstone’s roads for automobile travel beginning on the north end of the park. Spokesman Al Nash says over-snow travel between Mammoth Hot Spring and Norris Junction ended Sunday evening and the first thing Monday morning, park road crews began making their first pass with plows to clear a lane south from Mammoth. Nash says a brief spring bicycling season is offered on some park roads after the plows safely clear traffic lanes and before the roads are ready for automobile travel.  Once they are open to cars, visitors to Yellowstone will be impacted by one major road construction project this year between Madison and Norris through Gibbon Canyon where delays of 30 minutes or more are possible.