The city is testing a new warning system that will tell drivers when road conditions are ripe for black ice to form. The icy road sensor system is a just a bit bigger than a hockey puck.

A plastic disc is embedded into the asphalt and inside the disc is a temperature sensitive dye. It's usually beige, but when the temperature on the surface of the road drops below 3 degrees, it changes colour. By the time the road surface is at freezing, the puck is a bright red.

"This is just a tool," says Mac Logan with the City of Calgary Roads. "It's just another piece of information for motorists to use. It still comes back to what's behind the steering wheel, controlling that vehicle....people have to use care and due attention when they are driving."

Calgary is one of 12 cities testing the discs, which cost 25 dollars. The City of Calgary, Roads, will set up test sections on Crowchild Tr., 14 St. S.W., MacLeod Tr., Barlow Tr., Country Hills Blvd., and the Trans-Canada Highway at Bowfort Road.