N.W.T. Department of Transportation officials closed the winter ice crossings on the Dempster Highway Wednesday at noon.
The Peel River ice crossing near Fort McPherson, and the Mackenzie River ice crossing near Tsiigehtchic are closed to all traffic.
That's an issue for six-time Olympian Clara Hughes, who left Inuvik by bicycle this morning, heading for Dawson City, Yukon, as part of her Big Ride across Canada.
The Department of Transportation says a cyclist will be flying across the closed road in a helicopter.
Ferry service at the river crossings will start once the ice clears.
Officials say drivers on the N.W.T. side of the highway should watch for overflow and potholes.