London, April 5 : Researchers at a French company have developed a new temperature-sensitive varnish for road surfaces that can turn pink in icy conditions, thus helping to prevent ice-related traffic accidents in future by serving as a warning to drivers.
According to a report in New Scientist, the varnish is made of a polymer containing a thermochromic pigment, which 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.
This winter, researchers at Eurovia, the company who developed the varnish, tested it on roads at different sites in France.
They painted squares around a meter across onto the roads and observed how the normally transparent varnish turned dark pink when temperatures dropped below 1 degree Celsius. When the temperature rose back above 2 Degree Celsius , the coating became colourless again.
"The beauty of the system is that information would be available in real time, allowing roads to be salted exactly where and when needed, or cautioning drivers to take extra care as roads start to become dangerous," said project leader Thomas Devanne.
According to Devanne, the coating could be used anywhere that becomes icy in winter - on roads and highways, or even on pavements to warn pedestrians to watch their step.
"Our first on-site tests have produced some encouraging results - the coating is resistant to harsh weather conditions and is mechanically resistant too," he said.
"However, we still have some work ahead of us to optimise the final product," Devanne added.
The two most important challenges are improving the night visibility of the coating and ensuring it lasts throughout the summer months, when it would be exposed to higher levels of ultraviolet rays from the Sun.
"I think this is a very nice idea but the UV stability of the pigment used in these thermochromic materials will be one of the key issues to be addressed," said Stuart Rowan of Case Western University in the US.
"We have been proud to test this new coating, whose purpose is to make our roads safer," Devanne told New Scientist.