Wired has an interesting article on the use of glow in the dark paint on roadways. It seems like an ingenious way to cut power consumption for street lights. I’m not entirely sure I really get the point of the temperature sensitive warnings though. The road getting icy when cold is generally common sense. It seems like it would be better if cars were just required to display outside temperature and perhaps have an audible alarm when it drops below freezing. The cost of this in a modern car would be relatively low as the electronics needed are all cheap. The added benefit would be both a visible (dashboard light) and audible (tone) warning.
Simple ideas can change things.