FOI request reveals tolerance of UK speed cameras

10.55 | 29 April 2019 | | | 10 comments

The majority of fixed speed cameras in the UK are only activated by motorists going 10% plus 2mph above the speed limit, an investigation has confirmed.

Freedom of Information requests to 33 police forces in England, Scotland, Wales and Northern Ireland – carried out by AutoExpress – reveal 22 forces adhere to the 10% plus 2mph prosecution guidelines set by the National Police Chiefs’ Council.

However, eight forces were unwilling to reveal the threshold they use over concerns it could encourage motorists to speed.

Two forces – the Metropolitan Police and Lancashire Police – are more lenient, adopting a 10% plus 3mph threshold.

The Met says this is ‘a proportional response to the high volumes of traffic’ in the Capital, while Lancashire Police says it operates this threshold ‘to ensure greater tolerance or discretion’.

Speaking to AutoExpress, Edmund King, AA president, said it is sensible to have some flexibility with speed-limit enforcement, “as the last thing we need is drivers concentrating solely on the speedo and not the road”.

All police forces confirmed their thresholds apply to both fixed and average speed cameras.



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    Asking the police what their speeding enforcement tolerance is, is like asking a supermarket what their tolerance is of number and value of items stolen per shoplifter. In both cases, it raises suspicion and begs the question, “Why do you need to know?”.

    Hugh Jones
    Agree (11) | Disagree (20)


    You seem to have a strange view on the meaning of the word “comply”. Travelling at 34 mph in a 30mph limit is not “complying”. Maybe you mean “not getting penalised”.

    And as I said in my first post, if in order to keep to any maximum speed drivers are having to concentrate so much on their speedometers that they are not properly aware of what’s happening outside their cars, then they shouldn’t be driving. It doesn’t matter whether the maximum speed is 20mph, 24mph, 30mph, 35mph, 40mph, 46mph, 50mph, 57mph, 60mph, 68mph, 70mph or 79mph.

    Rod King, Warrington
    Agree (10) | Disagree (23)

    Rod, firstly, my comments are, as usual, based solely on my firm beliefs that public roads should be safe and accessible to users of all modes equally, and without prejudice, and that the responsibility for that safety and accessibility lies with those charged with providing the system.

    As for tolerances, no-one is saying it is easier to comply with a 35mph limit than a 30mph limit, what is being said is that is is easier to comply with a 30mph limit within a tolerance of 5mph than it is to comply with no tolerance – and that is a fundamental fact of reality. And the easier it is to comply, the more likely it is to be complied with and the safer that compliance will be. I’d rather share the roads with drivers who are fully aware of what’s happening outside of their cars but travelling a mph or two above the limit than with drivers who are travelling at exactly the limit, but is who are having to concentrate so much on their speedometers that they are not properly aware of what’s happening outside their cars. I would prioritise safety over motorist prosecution every time.

    Charles, Wells
    Agree (24) | Disagree (6)


    Can you explain how it is easier to stick to 35mph than 30mph? The idea that it is somehow “safer” have a 5mph tolerance and stick to 35 just because others also use the tolerance is not logical. Take the tolerance away then others will also be subject to the same conformity pressures.

    Any inaccuracies with hand held devices tend to be due to the cosine rule and hence will always under-record the actual speed. Other countries manage perfectly well to fine and prosecute for exceeding the speed limit by 2.5%. To try and justify a 5mph margin on the basis that a 0.01mph margin would be unenforceable is illogical also.

    It looks like your comments are driven by “driver exceptionalism” rather than logic.

    Rod King, Warrington
    Agree (11) | Disagree (25)

    Hugh, as there will always be a necessity for a tolerance to allow for the inherent inaccuracies in speed trap speed measurement technology, why not embrace it, rather than imply it is a concession given to bad drivers.

    Charles, Wells
    Agree (16) | Disagree (7)

    Do what I do Charles (along with many others) – drive below the limit – and allow a margin. It doesn’t say anywhere that you have to drive as close to the limit as possible. As for ‘no-one wants to go slower than the limit’… speak for yourself. The majority of drivers do actually drive below the limit.

    Hugh Jones
    Agree (12) | Disagree (16)

    Rod, Hugh, clearly the speed limit doesn’t change because of the tolerance. The reason a tolerance makes it easier for the driver to remain safe is that it’s easier to stick to 30mph within 5mph without looking at the speedo than it is to stick to 30.00mph, and clearly no-one wants to go slower than the limit (as to do so could risk attracting unwanted attention as hesitant drivers). And as for the accuracy of car speedometers, that isn’t a reason for the tolerance, it’s the accuracy of the speed traps – they cannot be relied upon to give a 100% precise reading – with the hand-held ones being particularly prone to inaccurate readings. The last thing the authorities want is 1000s of successful appeals based on the fact that no instrument could possibly be relied upon to prove a 30.01mph speed in a 30mph limit.

    Charles, Wells
    Agree (9) | Disagree (10)

    Very useful! This nearly matches my FOI requests to every police force back in 2015.

    From those who declined to respond to these FOI requests, Bedfordshire, Cambridgeshire, Greater Manchester, Hertfordshire responded to mine in 2015, and at that time they applied the traditional ACPO guidance of 110% + 2mph for enforcement

    Scotland, despite the attempts of literally every person I know, have not furnished a response, ever. Anecdotal reports suggest 110% + 2mph however

    Nottinghamshire originally declined to respond to my FOI request however following a review, they indicated that they began enforcement at 110% + 3mph

    West Yorkshire appears to have reviewed its stance, previously this was 110% + 3mph

    Essex declined to answer my FOI request originally, stating that as it could not furnish the answer for one, it decided to not furnish the answer for all. An interesting answer but it is ultimately lawful. There was however some oddball documentary that was broadcast a few years back on TV where one technician was filmed setting a Gatso to enforce at 48mph in a 40mph limit!

    Staffordshire and West Midlands also declined to respond back in 2015, and also decided to decline to respond after an internal review.

    David Weston, Corby
    Agree (4) | Disagree (4)

    Well said Rod.

    I am surprised that so many of the camera authorities revealed their threshold in the first place.

    Hugh Jones, Cheshire
    Agree (9) | Disagree (11)

    The comment from Edmund King about a tolerance ensuring people do not have to keep checking their speedo is illogical. If drivers know that the tolerance in a 30 limit is 35mph, how is it easier to keep within 35mph than 30mph?

    Its just an invention to enable drivers to exceed the speed limit. When speedos had a plus or minus tolerance it may have been acceptable, but current regulation allow no negative tolerance so no driver can ever claim that their speedo was showing less than actual speed.

    If drivers cannot keep to a limit without taking their eyes off the road for so long that they are unsafe then they shouldn’t be driving. It really is ridiculous for drivers to claim children need to be trained and able to take responsibility to cross roads safely when drivers are allowed to exceed the speed limit on the basis that they are too dim, stupid or bad a driver to keep within a speed limit safely.

    Rod King, Warrington
    Agree (14) | Disagree (24)

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