Cat's eye (road)

A cat's eye is a device used in some countries for road construction. A safety device, it consists of one or more small retroreflectors built into a sturdy housing, capable of surviving as vehicles pass over it. They are placed along road markings, as they serve to highlight these markings at night. They are particularly useful when lighting is poor and in addition to reflective road markings.

Cat's eyes were invented in 1933 by Percy Shaw of Yorkshire in England. The name "cat's eye" comes because the inventor was inspired when he saw light reflecting from cat's eyes. They became popular in Britain during WW2, in the era of blackouts. The Government realised that drivers needed to see where they were going, even if there was a air raid and hence a blackout taking place. Cat's eyes use a system where the light is reflected from the car's headlights, thus allowing a limited amount of light.

Various types of cat's eye exist. In Britain white cat's eyes are used for the centre of a road, lane markings, or soft traffic islands. Red cat's eyes are placed along the hard shoulder of a motorway, and orange cat's eyes are placed along the edge of the central reservation. Green cat's eyes denote joining or leaving slip roads at junctions, and blue cat's eyes are used for police slip roads.

In Ireland, white cat's eyes are used in the central reservation, yellow on hard shoulders, and green at junctions.

There are self-illuminated versions, either wired to a power supply or using solar power. These increase visibility range.

See Also: Retroreflector

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