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Invention and innovation: An introduction
Invention and innovation: An introduction

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10.3.1 Cats eyes and road conditions

Sometimes the discontent comes from the fact that there isn't a product to satisfy a particular need. Percy Shaw was a road mender who was aware of the dangers of driving along unlit, often fog-bound, roads. One night in 1933 he was driving his car near his home in the north of England when his headlights were reflected in the eyes of a cat. This inspired him to invent the cat's-eye reflector that, when embedded at intervals in the centre of the road, reflected a vehicle's headlights and made it easier to pick out and follow the course of the road (Figure 33).

Figure 37
Figure 37 Extract from the patent for cat's-eyes – an example of a highly successful patent for a simple but ingenious idea. ‘FIG.6.’ shows how a rubber insert (part ‘F’) cleans the lenses when they are depressed by a passing vehicle (Source: van Dulken, 2002)

With hindsight the need and the solution seem self-evident – like many ingenious ideas. But Shaw's act of insight was to recognise the need and work out a means by which it could be met.

Seventy years after Shaw's invention a new generation of cat's-eyes have been developed and have been tested in sites around the UK and several other countries. Called intelligent road studs, they have a built-in microprocessor and sensors that can detect different weather conditions as well as the speed of passing traffic (Figure 34). They are powered by a solar cell feeding a rechargeable battery.

Figure 34
Figure 34 (a) These intelligent road studs not only reflect but can also actively project light of different colours. (b) Intelligent road studs being tested on a public road (Source: courtesy of Reflecto Ltd)

In addition to passively reflecting light up to 80 metres, the studs can actively project light of different colours that is detectable at up to 1000 metres. When a stud detects fog it can emit a flashing white light. When it detects a significant drop in temperature it can emit blue light to indicate the possibility of ice. In a hazardous situation studs can leave a trail of orange lights behind passing vehicles to warn against following too closely. Studs can even communicate with each other so that, for instance, a vehicle detected on the wrong side of the road can trigger red warning lights in studs on the other side of a blind hill or corner.