How do average speed cameras work? Everything you need to know to avoid being fined
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Average speed cameras have been thrust into the spotlight as it emerged motorists face punishments for driving just 1mph over the limit .
Cameras are now said to cover more than 250 miles on British roads 24 hours a day and seven days a week.
They feature both at permanent sites and on 'smart motorway' roadworks such as the M1 near Leicestershire, Nottinghamshire and Derbyshire.
And it has proved effective in some areas after Scottish Transport Minister Humza Yousaf said there had been a "significant positive impact" on the A90 between Dundee and Stonehaven since becoming operational in October.
But plenty of theories have been spouted about how to avoid detection, including changing lanes and driving at certain limits.
We've taken a look and separated the fact from fiction.
Here's how average speed cameras work - and how you can avoid being caught speeding.
How do average speed cameras work?
The multiple cameras (at least two) are set at separate locations along a stretch of road (at a minimum 200m apart) and are synchronised to record the exact time that each car passes using number plate reading technology.
Then a computer will work out the average speed between the cameras to determine if the car was over the speed limit, the Derby Telegraph reports.
Some people wrongly think that each camera records a driver's speed as they pass each camera before the computer works out the average speed as the car passed every camera - this explains why some drivers think they can speed up between the cameras and slow down as they pass them.
(Image: PA)
But doing this is likely to land you with a fine - the cameras simply record the time you pass them and the computer works out how long it has taken you to pass the distance between them.
Do the cameras work at night?
Yes. They are fitted with infra red illuminators to ensure they work night and day, and all weathers.
Can the cameras run out of film?
No. Unlike some other speed cameras, average speed camera information is saved to a computer.
(Image: Photolibrary RM)
Can the cameras catch motorbikes?
Yes. The cameras are equipped to capture all types of vehicles.
If a vehicle changes lanes will they avoid any fines?
No. The cameras calculate for lane changes. But this myth can mean people dangerously switch lanes increasing the chance of crashes.
If a driver passes more than two sets of average speed cameras in a sequence while over the speed limit, will they be fined more than once?
This is unlikely. Only certain cameras in the sequence are usually 'paired', so where, for example, there are four in a sequence it may be your speed between the first and third that is recorded, or the second and fourth or first and fourth, and so on.
(Image: PA)
But you will not know which ones are recording your number plate at any time.
If you are less than 10 per cent above the limit, will you get a ticket?
It has been commonly assumed by many drivers over the years that you will not get a ticket so long as your speed does not exceed the limit by more than 10 per cent plus 2mph. This is because of guidance to officers from the National Police Chiefs Council.
Several police forces nationwide have indicated that drivers can expect far less leeway, as cameras become more accurate - and the law states that a driver can receive a ticket as soon as they have exceeded the limit, even if it is only by 1mph.
How can you avoid getting a fine?
There is only one way to be sure that you do not get a ticket from average speed cameras - and that is to drive without speeding.