Color Changing Roads

France's Eurovia is developing a thermosensitive road varnish that changes color to indicate freezing and dangerous conditions. Kinda like those winter gloves and sweatshirts we all had as kids, a colored pattern or message would appear when it gets really cold, and vanishes once it warms back up. The idea is to warn motorists of dangerous conditions while avoiding the environmentally wasteful practice of dumping tons of salt onto the roads.