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Traffic light and speed cameras – how they work

Speed and red light cameras are now a common feature of Britain’s roads, having been first introduced in 1991. Speed cameras are the most common and the most well known, but there are also traffic cameras to monitor congestion and traffic light cameras to catch drivers running red lights.

A speed camera attached to a gantry

Speed cameras are widely debated, with detractors saying they’ve become a revenue-raising exercise by the government. 

Recently, 20 mph speed cameras have been rolled out across the UK which have been met with mixed reviews by the public. 

Supporters point to their effectiveness in reducing road casualties. According to The Royal Society for the Prevention of Accidents (RoSPA) 45% of pedestrians are killed when struck by a car going at 30 mph or less. This is reduced to only 5% when going at 20mph or less. 

Whatever your stance, it pays to know the different types of cameras and what they do.


New 20 mph speed cameras to be rolled out across the UK

Local councils have introduced 20 mph zones across the UK and installed speed cameras to monitor them. These zones are mostly in residential areas or busy pedestrian streets. 

In Wales, these zones have been rolled out in 8 areas including:

  • Abergavenny
  • Severnside
  • Central North Cardiff 

In England, lots of cities have brought in the 20 mph limit. Some of these include:

  • Lancashire
  • Bath
  • Oxford
  • Birmingham

Edinburgh, Fife and Glasgow are just a few of the areas in Scotland that have introduced the 20 mph speed limit. You can find the full list on the 20’s Plenty For Us website. 

The 20 mph cameras have caught over 23,500 motorists going over the 20 mph speed limit across the UK. Sources online revealed that some cameras caught 1,100 drivers breaking the speed limit within the first 24 hours of their launch. 

Despite having mixed reviews from the public, the 20 mph zones and their cameras have a number of benefits, including:

  • Reducing road collisions
  • Potentially encouraging more pedestrians to walk or cycle as they could feel safer in a 20 mph zone
  • Lower emissions on these roads If people are more inclined to walk or cycle
  • Improving health and wellbeing 
  • Improving the safety of streets

What are traffic cameras used for?

Traffic cameras are used to monitor the flow of traffic on motorways, busy roads and at major junctions. 

This helps with the management of congestion and, in the event of an incident, can ensure help is called for as soon as possible.

They are not used to monitor drivers’ speed.

Traffic cameras are operated by different entities. Highways England says it uses over 1,500 cameras to help it manage traffic on the trunk road and motorway network in England. 

Traffic cameras, which are mounted on 12m high masts on grass verges or on overhead gantries, aren’t easily seen. 

The cameras give a bird’s eye view of what’s happening, which helps the operator decide on the support needed.

You might see the images captured from these boxes on traffic bulletins. 

In fact, anyone can access traffic camera images on Traffic England’s website.


What are traffic light cameras?

Also known as red light cameras, these devices are installed at traffic lights on major junctions and can snap any driver running a red light.

The systems are activated when the lights turn red and use sensors to detect - and then photograph - any vehicles that pass through the junction during that time.


Do all traffic lights have cameras?

Not all traffic lights have red light cameras.

On a practical level it wouldn’t be cost effective to fix red light cameras onto every traffic light, considering the cost of implementing and operating them.

However, don’t be tempted to chance running a red light. 


What happens if I run a red light?

Running a red light is extremely dangerous and that’s reflected in the penalties.

If you get caught by a red light camera you should get a fine of £100 and three points on your licence.

You may also be asked to go on an educational course if you’re caught running a red light.

When you come to renew your car insurance, you should be asked about driving any driving offences and your premium could go up too.

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Why do we need speed cameras?

Speed cameras are an important part of the government’s road safety strategy and are the key tool in its arsenal to tackle speeding.

The latest speed compliance statistics (for July to September 2021) show that levels of speeding have dropped over the last two years.

It found that 48% of cars broke the speed limit on motorways, compared to 9% on 60mph roads. Speeding is most prevalent on 30mph roads, with 52% of drivers breaking the speed limit.

Other measures to reduce speeding include physical restrictions like speed bumps or chicanes often found in residential areas.

Thankfully, our vehicles and even sat navs all helpfully remind us of a speed limit. And, of course, there’s the speed awareness course offered to those who exceed the speed limit marginally.


What’s the difference between a fixed and mobile speed camera?

Speed cameras monitor the speed of cars and take photos of those that break the limit and there are two types used in the UK: fixed and mobile.

Fixed cameras are usually placed around accident hotspots. Many sat navs can pick these up. 

Since October 2016, all working fixed speed cameras have to be yellow to maximise visibility.

This was in response to the high level of questions raised around speed cameras and widespread public feeling that it was a money-collecting exercise.

However, the DfT still allows for covert cameras to be “used where it’s considered to be in the interests of road safety.”

Mobile speed cameras, meanwhile, are typically used by police who can go wherever they think there is a need.  They are likely to be housed in a parked van or you may see police by the side of the road with laser guns or hand held radar equipment.

Again, you usually find them in accident black spots or roads where speeding is common. They may also be used as part of safety campaigns.


What are the speed camera types in the UK?

Getting caught out by any one of these speed camera types could land you with points on your licence and a speeding fine

For first-time offenders, there’s a choice between a speed awareness course or points on your licence.

Of course, penalty points on your licence could mean higher car insurance costs, so many opt for the course when given the choice.

Here are some of the most common speed camera types:

Fixed speed camera: GATSO

A rear-facing camera that measures how far a car has travelled between two points, and flashes to take a photo of the rear number plate.

White lines often accompany GATSO cameras to show how fast a car is going.

Fixed speed camera: TRUVELO

A front-facing camera that uses sensors in the road to determine the speed of a car.

Unlike some types of speed camera TRUVELO doesn’t flash, so you might not notice if you’ve been caught. Because they’re front-facing, the camera usually captures the driver’s face.

Average speed camera: SPECS

You find this type of speed camera attached to gantries on dual carriageways, motorways and smart motorways. SPECS cameras monitor average speed.

They keep an eye on four lanes of traffic and use automatic number plate recognition (ANPR) to photograph every car.

Variable speed cameras

Unlike SPECS, these speed cameras are only active when there’s a temporary speed restriction on the motorway.

Also, these cameras can only monitor a single lane at a time, so there may be several cameras tucked inside a gantry.

Mobile speed cameras

Mobile speed cameras use either lasers or radar to catch speeding drivers. These can be mounted in speed camera vans or can take the form of hand-held speed cameras propped up by officers.

Fixed cameras are subject to weather conditions – a particularly rainy, foggy or snowy day could mean that a camera is inoperable. Mobile cameras are able to pick up the slack when this happens.

DVSA/DVLA cameras

The DVSA has a network of cameras around the country that use ANPR technology to catch uninsured drivers or cars that don’t have valid tax.

The DVSA and DVLA share data with one another to make sure that all cars on the road are above board.

Traffic CCTV

Primarily, these cameras keep an eye on the flow of traffic to help with congestion and accidents.

However, some areas use CCTV to catch drivers who stop in box junctions or use bus lanes.


Can I check if I’ve been caught speeding?

You can’t check if you’ve been caught speeding by any of the different types of speed camera. If you’re caught speeding by a camera within 14 days according to the DVLA you’ll be sent either:

  • Notice of Intended Prosecution
  • Section 172 notice.

Don’t ignore the notice or you could end up in court. Once you’re given the notice you could receive either a Fixed Penalty Notice (FPN) or you may get a letter telling you to go to court.

If you’re stopped by the police, they might:

  • Give you a verbal warning
  • Give or send you an FPN
  • Order you to go to court – with a letter sent telling you what to do.

How do average speed cameras work?

Some city councils and police operate an Average Speed Enforcement (ASE) camera system.

It’s another road safety measure meant to positively influence driver behaviour and compliance with the set limits on roads.

The ASE cameras detect cars, calculating their average speed by measuring the time taken to travel between fixed points.

Digital SPECS cameras monitor the vehicle’s average speed on a stretch of road, creating ‘Speed Control Zones’. They’re more likely to help keep speed down over a longer period.


Do mobile speed cameras flash?

Some mobile speed cameras flash and some don’t. The presence of a police officer or speed van tends to act as a deterrent on its own.

Drivers may be alerted that they’ve triggered a camera through a flash in their rear view mirror from a speed camera.

There’s not much you can do except wait and see. There’s a formal process by the police in place and if you have been caught for speeding you’ll receive an NIP within 14 days.


Do average speed cameras flash?

Average speed cameras do not capture your speed with a flash. 

They monitor your speed over a length of road, instead. This is to stop people slowing down before they see a camera, just to speed up once they've passed it.


Are speed camera detectors legal in the UK?

Speed camera detectors are legal in the UK. However, they are illegal when driving in many countries across Europe.

For example, when driving in France you even need to turn the feature off on your built-in sat-nav.

Speed camera detectors let drivers know where speed cameras are as they’re driving – either through a device sitting on a dashboard or through a smartphone app.


Are speed camera jammers legal?

‘Jammers’ that block the signal from police speed cameras are against the law in the UK.

Get caught using one of these and you may be fined, and potentially lose your driving licence. If the court deems that you were perverting the course of justice, you could even receive a prison sentence.

Cameras often show an error message when affected by a jammer, which alerts operators to the fact that you might have one.