Cats' eyes and road safety

They are only a couple of centimetres long and wide yet they are estimated to have prevented thousands of accidents on the roads. Their design has remained largely unchanged in over 70 years. They rarely need to be cleaned because you run them over every day. So what are they? Cats' eyes.

These clever little things were first invented in 1934 by a Mr Percy Shaw of Halifax, Yorkshire. As the story goes, he noticed that he had been using some tram lines to navigate in poor light and missed them when they were removed. He realised that there was the space for an invention which motorists would benefit greatly from - so he made it.

Although most of us use cats' eyes every time we go out in the car, we pay little attention to them and they are a mostly overlooked piece of skilful engineering. The design of cats' eyes is extremely ingenious, which is why they have only undergone minor changes whilst other types of technology have been amended and improved.

A cat's eye consists of two reflective glass beads insetted into a rubber frame. When headlights shine on the beads they provide a bright "retroreflection" where the light is reflected back along at the same angle it entered.

Obviously it is crucial that they don't get dirty, otherwise the reflection will be much less effective. However, Mr Shaw realised this possible problem and took it into account when designing the first cats' eyes. When motorists drive over them, they are pressed down and a small wiper is activated in order to clean the dirt off. This process is aided further by the fact that water collects in a small well in the frame, giving the cat's eye a quick wash when it is depressed.

When asked what cats' eyes do, most people would say light up the road. Whilst this is true, they also provide a surprising number of other functions that improve road safety in a variety of ways.

The fact that they are depressed when you run them over means that you can both hear and feel that you are changing lane. This multi-sensory way to alert people that they are straying from their lane can both wake sleeping drivers up and refocus the attention of motorists who aren't looking where they are going. It is likely this prevents many accidents and prevents many people from losing their cheap car insurance rates because they have had to claim on their motor insurance policy.

Cats' eyes are also employed by road workers when temporary lanes need to be marked out, typically on motorways. This flexibility is extremely useful, as it is vital that motorists are clear about the exact path they should be taking when the normal lane layout is disrupted by road works.

Whilst originally developed as white, coloured cats' eyes are now in common use. Different colours designate different areas of the road, thereby conveying valuable information to the motorist. Green cats' eyes highlight a junction, white follow the centre of the road, whilst red mark out a motorway hard shoulder and blue define police slip roads.

However, it seems that the days might be numbered for reflective cats' eyes with the advent of solar-powered LED versions. These mark out the road well ahead as they do not require headlights to fall on them and are much brighter than the traditional type. They enhance drivers' view of the road from 80 metres to 1000 metres on a clear night, which is a substantial improvement. These have already started to be installed on some roads in the UK and have been greeted with positive comments from many drivers.

Despite these benefits, however, suggestions that they could cause epileptic fits in some people and rumours that they will not last as long as traditional cats' eyes could keep Mr Shaw's remarkable invention on the UK's roads for years to come.

Slight modifications to reflective cats' eyes may be the compromise that road safety experts are looking for. Intelligent Cats' Eyes (ICE) which turn blue when the temperature falls to icy levels have been developed by a young enterprise team in Ireland. If implementable, this kind of safety feature could reduce accidents in cold weather and so save many people from having to make a car insurance claim.

 

For more information, please see:

• Why choose duck2water?
• How to buy online
• Breakdown cover
• Glossary
• Customer testimonials

Get a cheap car insurance quote now!