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Variable speed cameras explained

Variable speed cameras appear and are used on many motorways in the UK, including the M1, M25 and M62. Unlike other fixed cameras and average speed cameras, variable speed cameras don't tend to enforce the road speed limit 24/7, but are used when the motorway's national speed limit, normally 70mph, is temporarily lowered e.g. 60mph or 50mph. These temporary speed limits are set and changed automatically at the press of a button by operators at a control room.

Speed cameras are sited on overhead gantries above each lane of moving traffic, meaning gantries can have up to four or five individual speed cameras targeting each lane of the motorway.

Cameras used at these locations are often the popular Gatso ones, when a vehicle travels in excess of the posted 'variable' or 'temporarily' speed limit the camera is triggered and photographic evidence of the speeding offence is recorded.

On variable speed cameras a motorist comments:

I have just received a NIP for a exceed of a variable speed limit on the M1 on 8/2/18 at 4.41am.

I was doing 58mph when the matrix was saying 50mph, yet the two sets of matrix before were flashing 60mph and the next one after 60mph and the next one the National speed limit! There was no congestion, no road works, no debris and no reported accident.

Variable speed limits

By their very name variable speed cameras are used when a variable or lower speed limit is enforced on a motorway, e.g. 40mph, 50mph or 60mph speed limit. Motorway speed limits are lowered when traffic congestion increases at peak times or when there is an accident in the road ahead. This is to help ensure the motorway continues to move as free flowing as possible and ensure safety of motorists along the section or sections of motorway where the temporarily or variable speed limit applies.

Points and Penalties

The absolute minimum penalty for being caught speeding on the UK's roads increased 66.7% in July 2013 from £60 to £100 fine. A minimum of 3 penalty points will also be added to your licence.

However, depending on the road speed limit and your actual recorded speed in the speeding offence a court summons may be generated in place of the Notice of Intended Prosecution (NIP) through the post with the code SP10, SP20, SP30, SP40 or SP50. For more information click here.

Where are variable speed camera used?

Variable speed cameras are used on a growing number of motorways in the UK and are sometimes also used on sections of so-called 'Smart Motorways'. During peak times the hard shoulder on a Smart Motorway is also used as an additional lane to increase the capacity of the motorway. When a motorway's speed limit is temporarily lowered, variable speed cameras are is activated to enforce the speed limit.

Pictured below Smart Motorway - with congestion and use of the hard shoulder for motorists.

Variable or temporary speed limit speed cameras should not be confused with average speed check cameras, the difference being average speed cameras such as SPECS and VECTOR cameras enforce the road speed limit 24/7. Variable speed cameras in comparison tend to only be used when the normal or national speed limit has been lowered.

Variable speed cameras to operate 24/7?

In general variable speed cameras are only used when a motorway speed limit is temporarily reduced. However, this may change in the near future as the Bedfordshire commissioner, Olly Martins, has said he is "actively looking" at ways to generate more money for Bedfordshires Police force's budget. One measure he has suggested is to turn the M1 variable speed cameras permanently on.

According to the BBC News website published November 2015: He told the committee that unless the force's grant funding was "realigned to the reality of the county's policing challenges" he would have to use his powers to permanently turn on the cameras between junctions 10 and 13, one of the busiest stretches of the motorway. Read the full story here.

Variable speed camera locations

What's your view and experiences with variable speed cameras on the UK's motorways? Tell us here.

Want to know where the UK's variable speed cameras are as you drive? Here at SpeedCamerasUK.com we have a UK database of speed camera locations. This database also includes SpeedCurb, Truvelo, New Truvelo, SPECS, Peek, Traffic Light speed cameras and more. To read more about the speed camera types click here.

Variable Speed Camera Questions and Answers

Question: I was driving on the M25 approaching the Dartford Crossing and due to a traffic disruption the speed limit was gradually being reduced. As I approached a gantry displaying 50mph I could see that the next gantry further ahead was displaying 40mph, however by the time I was approaching this particular gantry the displayed speed had increased to 50mph. I did not see the exact point when the speed increased. I passed the gantry at 50mph but the camera flashed.

I have not received a fine yet as this only happened on Saturday, but can I argue this? Will there be any evidence that the speed limit displayed on the gantry had increased? Is there a grace-period for this instance?

Answer: A few years ago we contacted Surrey Police on this very point. They confirmed that for their variable speed limit cameras on the Surrey section of the M25, they give motorists a 2 minute grace period when reducing a speed camera limit. You could contact Essex Police for them to confirm their policy with regards to the temporary reduction in M25 speed limits and their enforcement.

Question: I was hoping you could advise me on a question regarding setting a variable speed limit speed camera off on a motorway.

Earlier this evening I was driving in a temporary 60mph zone on the m62 (digital 60 sign surrounded by the red circle). I was travelling at 60mph and then I saw the next digital sign ahead of me change to the national speed limit (70mph) so I accelerated my speed to 70mph in accordance to seeing the sign change. When I passed under the sign the speed camera flashed me. Presumably there is some kind of lag time between the speed sign changing and the cameras knowing about the change. What is likely to be the outcome of this as I haven’t done anything wrong, I was sticking to the speed limit but I still got flashed and am concerned about what could happen.

Any advise you could give would be much appreciated.

Answer: I would suggest you put your question to the Police force for that section of the M62 for a definitive answer. However, we put this question to Surrey Police a few years ago and they confirmed to us that they give motorists a grace period of 2 minutes when changing the overhead gantry signs to lower the variable speed limit.

Question: I know they all say that(!) but basically I do not speed. I have been clocked at 59mph in what they say was a 50mph zone on the M62. My gut feeling is that for me to be doing that kind of speed, that the 'warning' roundels must have been saying '60mph'. Is there anyway I can find out what was actually showing at that time? It's just that the photo the police have sent is not sufficiently clear to show what the red circles were saying. Can you please advise?

Answer: Possibly Highways England keep a record of variable speed limits? It might be worth contacting them to enquire?

Question: I've just been sent a summons for travelling at 101mph on the M25 between J14 and J15. At the time there were no lights light on the gantries with regards to speed limits in force, I had thought that if these were not lit the cameras did not work, is this not the case?

Answer: Many speed cameras on UK roads use infra-red to help them operate 24/7. In addition, many police forces are choosing to enforce the 70mph national speed limit when variable or reduced speed limits are not in force.

Question: Just a question regarding smart motorway cameras. This morning I was on the M3 the gantry was showing no speed limits on it and as I passed it at around 85mph the camera flashed twice. Have they always been on when there is no average limit in place and what do you think the likelihood of a fine coming through?

Answer: SpeedCamerasUK.com is not connected with any UK Police or other local authority. We don’t run, install or operate any speed camera – we just list where they are and information about them. For a definitive answer I would suggest you put your question to the local Police authority

However, what we can say is that some Police authorities do use the National Speed Limit (NSL) when not enforcing a reduced or variable speed limit.

Question: I have received an NIP for the M5 at 87mph. The photo was taken by an overhead gantry camera which was not illuminated at the time. Does this affect the validity of the NIP?

Answer: It sounds like the speed camera was set to a national speed limit (NSL) of 70mph. The sign does not have to be illuminated for the NSL, only during a reduced lower speed limit e.g. 50mph.

Question: M25 is 70mph highway. If suddenly next gantry display the temporary speed limit e.g. 60mph, how much time / buffer do i have to reduce the speed or the speed cameras on the same gantry can record my offence. If you look vice versa you won't enter accelerating in the faster speed limit, police has the right to install speed cameras just before the new speed limit, so accordingly you should start slowing down immediately after passing the reduced speed limit.

Answer: Variable speed limit speed cameras, such as those on the M25 gantries enforce the speed e.g. 60mph they are displaying at the point they are displaying them. When speed limits suddenly change e.g. 60mph to 50mph, there is normally a 2 minute grace window given.

Question: Today I got flashed on M25 while doing 70mph. This was because of 50mph speed limit due to incoming roadwork's. The thing is, the time was around half past midnight and there were hardly any cars on the road (only one on other lane who also got flashed..). The actual road works were about mile away. I think there were many people who got caught that night. Obviously I have not received a letter yet, but if I do, will these circumstances help me in anyway?

Answer: The speed limit is the speed limit, if signs were clearly advising you of the road (enforced) speed limit then it is a fair cop!

Question: I got flashed yesterday at 4am on the M25 in lane 1 at about 85mph. This was on the clockwise section somewhere around the A3 area. Never known speed cameras to be active without variable speed limits being on before, is this now the case?

I slowed down on this almost empty road wondering what / why etc. I still had another 300+ miles to go. 10 minutes later I got flashed again overtaking a lane hogger sitting out in lane 3! Reduced to crawling along after this.

Answer: SpeedCamerasUK.com is not connected with any UK Police or other local authority. We don’t run, install or operate any speed camera – we just list where they are and information about them.

I would recommend you put your question to the Police force(s) who operate the speed cameras.

Question: I was travelling on the M25 and the overhead signs were saying 40mph, so I was doing 40mph. A car came through going a lot faster and set the cameras off. So will that effect me because I was on the white camera lines aswell?

Answer: The white lines painted onto the roads surface provide the police with your vehicles speed. In the case of Gatso speed cameras sited in the overhead gantries, two photos are taken in quick succession. The police then use these two photos to see how far your vehicle travelled or moved in relation to the painted white lines, thus determining your vehicles speed.

If one vehicle was speeding and triggered the camera(s) and two vehicles or more were photographed. The police could easily identify the speeding motorist among the cars and/or other vehicles from the photographic evidence produced by the gantry mounted variable speed camera.

Question: Apparently I have been caught speeding on the M25 near Clackets Lane, I was traveling at 72mph, but it is a variable speed section which apparently was 60mph at the time. Now I know this section of motorway was clear and I do not recall the speed being lowered in this area, the motorway speed was reduced further up where I came on at M23 up until just after Godnestone exit. Is it possible to find out if the signs were on displaying 60mph at the point were the cameras are and am I allowed copies of the photos.

Answer: SpeedCamerasUK.com is not connected with any UK Police or other local authority. We don't run, install or operate any speed camera - we just list where they are and information about them.

You would therefore need to contact the Police force where the variable speed cameras were located for further help and assistance.

Question: I recently received a speeding fine after being flashed going through a variable speed zone at 82mph. The gantry signs were not displaying a maximum or variable speed limit, instead they were all off. It was around 8am on the M5 around Bristol. My question is, if the gantry shows no maximum speed applied then why is the camera flashing me? Why does this not happen on different variable speed zones? For example I have seen cars travelling in excess of 80mph through the variable speed zones on the M1 and M6 but have not been flashed. Shouldn't this rule be consistent across all UK motorways in order to save confusion?

Answer: Bedfordshire Police were toying with the idea of enforcing the national 70mph speed limit on the M1 via their variable speed cameras when no lower speed limit was being enforced. This could be the policy of Bristol and Somerset Police?

Individual Police forces can set speed limits and speed cameras as they deem appropriate.

Question: I have been caught as follows 18/5/16 19:15 M25 junction 23-24 50mph variable speed clockwise - caught at 60mph.

As I recall, which is difficult when you do trips more than occasionally, on that day the signs for speed were on then off then on then off with no hazard or traffic load around. How can I check if the cameras were showing these limits without due cause which can cause hazards in itself? This week I was more cautious as it was 40mph/60mph/50mph/40mph/60mph 40mph etc but the cars were pushing us to go faster when at 40mph and when at 60mph you suddenly had to slow when it showed at 40mph. dangerous!

Answer: You will need to contact the camera operator/local Police authority to confirm the speed limit at the time you were driving past the variable speed camera system.

Question: Can you please tell me if the speed cameras on smart motorways measure an average speed between cameras or if they just measure the speed as you pass them?

Answer: It would depend upon the speed cameras that are in place. For example if the cameras were Gatso or HADECS then these only monitor at a single fixed point, if however, they were SPECS or VECTOR cameras then these camera are designed to record/monitor average speed.

Question: I recently was travelling on the M4 where there are variable speed cameras. The speed was set at 60mph and I was doing 57mph. As I approached and the overhead camera went out of view I noticed the speed limit change on the sign a few hundred yards ahead down to 50mph yet the camera I had just gone under still flashed and I have received a fine notice. Is there not a delay in the time a speed changes to the time the camera becomes active? Are the police able to provide a photo of the speed limit on the gantry at the same time to prove that is what the speed was? A number of cars (all 4 lanes) got caught by the sudden speed change and even a couple following behind. Any help would be greatly appreciated.

Another motorist with a similar question asks: While travelling on M1 between junction 28/29 there was No variable speed limit on any signs yet a speed camera flashed the vehicle in front of me slowed down thinking he was speeding he wasn't even doing 70mph why would it flash??????

Another motorist with a similar question asks: I was travelling up the M1 this morning around 5.15am just passed junction 28 Derbyshire I was in the second lane following another motorist he had just gone passed the gantry and I was just approaching it and I noticed two bright flashes we were both doing the speed of around 78mph do these cameras flash and do they flash before you go past them any reply and guidance would be appretiated?

Answer: We have spoken to Surrey Police and they have confirmed that there is a 1 minute delay tolerance when the variable speed limit changes. Of course this is just Surrey Police's procedure for variable speed cameras and may differ from Police force to Police force.

Question: When the variable speed displayed on the gantry is lowered how much time is allowed for motorists to adjust their speed? If a motorist is passing under the gantry as the speed changes so they do not see the change, is the motorist prosecuted for speeding? What are the rules governing this situation?

Answer: SpeedCamerasUK.com is not connected with any UK Police or other local authority. We don't run, install or operate any speed camera - we just list where they are and information about them.

We therefore are unable to answer your question. The answer to your question will only be known by those that install and operate the variable speed limit cameras.

Question: New variable cameras at Bristol M5, if you were to pass through more than one speeding would separate tickets be issued? Or one ticket?

Answer: I would certainly be very surprised to hear that you or any motorist was prosecuted multiple times at a single variable speed camera speed limit e.g. 60mph.

If however the variable speed camera zone ends and then starts again and thus becoming a new variable speed check, then in this instance you may be prosecuted more than once on the same motorway or road.

Question: I just went under a gantry camera on the M20 doing over 100mph for 10seconds or so at this point the gantry speed limit signs wasn't on will I be prosecuted?

Answer: It will depend if Kent Police leave there speed cameras on all the time, and not just when enforcing a variable speed limit.

If you have been caught speeding, a NIP (Notice of Intended Prosecution) is normally sent out to the vehicles registered keeper within 14 working days.

Question: I was driving on M25 and due to a traffic disruption the speed limit was reduced to 40mph. I believe I passed through a Speed camera making 48mph. My question is, do these speed cameras adjust their limits with the local and temporary speed limit changes or do they always look for 70mph?

Answer: The M25 uses variable speed cameras. From a central control room the enforced road speed limit of speed cameras can be changed to match the speed limit displayed on the overhead gantry signs to enforce the temporary variable speed limit.

Speed camera alerts as you drive

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Last updated: 3rd May 2018