Stud surveillance

A British scientist, Martin Dicks,
claims to have developed 'intelligent' road studs that can warn
motorists of poor driving conditions by emitting different coloured
flashes of light (New Scientist, Vol 146, No 1972).

The stud comprises of a microprocessor and several sensors which
detect oncoming headlights, temperature and moisture content of
air, and water on the surface of the
road. The devices contain solar cells
and capacitors to enable them to
store energy from the sun and car headlights.