New Technology Turns Roads Pink in Icy Weather

A new polymer varnish will turn squares on roads pink in icy weather to help drivers make it through the snowy season, accident-free.

Dorothy, the Tin Man, and the rest of the Oz gang may have walked a yellow brick road, but most of us have had to cope with plain black asphalt for as long as we can remember. But a new scientific development could start making our morning drive a little bit brighter in snowy weather: Think pink.

In the new procedure, specially selected squares in high-visibility locations would be painted with a polymer varnish recently developed by France’s Eurovia company, which turns pink when the temperature drops below the freezing point of water. To someone driving down a city street, seeing pink would indicate the pavement itself was colder than the freezing point and any water on it might now have turned to ice, meaning that it might be a good time to get off the cell phone and slow down.

Thomas Devanne, project leader at Eurovia, put the varnish to the test this past winter at a variety of locations in chilly northern France. “We have been proud to test this new coating, whose purpose is to make our roads safer,” Devanne told New Scientist.

Thermochromic polymers aren’t a new phenomenon: They’ve been used in certain types of thermometers, and as visual indicators that show when foods and beverages are at their optimum temperature. A Japanese chocolate bar brand called “Dars” features thermochromic polymer circles on its boxes, which change color to show when the chocolate will taste its best.

Candy wrappers are meant to be thrown away or recycled; roads and sidewalks are another story. Researchers at Eurovia have been encouraged by the resistance their thermochromic varnish has shown to everyday wear and tear, though testing in the summer has yet to begin. The team at Eurovia will also have to ensure the temperature-induced color changes are both consistent and accurate.

So it may still be a little while before your street surfaces are looking pretty in pink – but we’re looking forward to seeing the color-changing polymer in action. Until then, we might just have to test out those Japanese candy bars instead (but only as research).