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.