New Scientist reports on an intelligent paint which turns roads pink in icy conditions.

The varnish is made of a polymer containing a thermochromic pigment. The same type of coating is already used to make bath thermometers and frozen food packaging that responds to temperature change. However, it is the first time such a coating has been used to monitor road temperatures.

…

the normally transparent varnish turned dark pink when temperatures dropped below 1 °C. When the temperature rose back above 2 °C, the coating became colourless again.

Sounds like a really cool innovation. They’re currently working on it to make sure that it also has some night visibility and won’t break when exposed to high levels of UV light during the summer months.

According to the driving theory test/highway code, the stopping distance at 70mph is 96m. In ice, you need to allow 10x a greater distance. That means the stopping distance at 70mph in ice is 960m… almost a 1km. I didn’t believe it when I first heard it.