Chad Clark's Open Journal : 2008-04-04

1) Road paint that turns colour in cold temperatures.

The New Scientist article reads:

  A new temperature-sensitive varnish developed by researchers at French
  company Eurovia can be applied to road surfaces to warn drivers about
  dangerous conditions. The technique still at the testing stage might help
  prevent ice-related traffic accidents in future, the researchers say.
  
  ...
  
  This winter, researchers at Eurovia tested the varnish on roads at
  different sites in France. They painted squares around a metre across
  onto the roads and observed how the normally transparent varnish turned
  dark pink when temperatures dropped below 1 degree C. When the
  temperature rose back above 2 degree C, the coating became colourless
  again.
  
  ...
  
  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.