ONCE, radar traps were the scourge of any motorist who wasn't too careful about sticking to the speed limit.

Today, that's history. Speed cameras are all that's needed to keep the feeling that Big Brother is watching backed up by photographic evidence that it's not easy to argue with.

The first you know about it is when the notice of intended prosecution drops through your letter-box.

You can contest the prosecution but usually it's easier to pay the fine probably £60 and you hear no more about it.

That is all part of a giant industry which brings in over £192 million a year in fines.

Against that, the cost of setting up the 10,000 cameras already in use may have been as high as £800 million each one costs £35,000 to buy, and up to £55,000 to install.

One the other hand, road casualities cost the taxpayer about £900million a year.

There are 3,500 road deaths every year, though death rates have fallen by as much as 50 per cent in areas where speed cameras are fitted.

Now motorists are being offered equipment which can tell you where a speed camera is waiting.

The GEODESY uses satellite communications to pinpoint the locations of thousands of speed cameras around the country and it's fully legal, say the makers. "It helps aid safer motoring through the identification of accident blackspots," they argue.

A MORI survey suggests that those who use such detection devices are 25 per cent less likely to be involved in an accident.

All statistics suggest that speed plays a major part in the likelihood and severity of accidents.

Familiar figures point out that at 20mph, 5 per cent of pedestrians struck by vehicles are killed.

At 30mph this shoots up to 45 per cent, and driving 10mph faster virtually doubles the likelihood to 85 per cent.

oRadar speed traps are still used in some regions, as well as laser detection.

Video cameras which check a vehicle's speed over a distance are also in use, working 24 hours a day.

Another type of camera, known as Racal, reads number plates regardless of speed, night and day.

The DVLA is setting up a nationwide network of them to spot untaxed cars.