Revealed: the margin for error for UK speed cameras

Speed cameras UK

It’s a burning question for UK motorists, be they speed-obsessed or strait-laced: what can you ‘get away with’ when it comes to speed cameras? Obviously, prescribed speed limits are there for a reason, and you should adhere to them to the best of your ability. But what is the margin of error, allowing for small excesses of speed? We look at the facts.

So what are the tolerances? It’s useful to know whether cameras will nick you on a decimal point, or whether there’s some leeway. Here’s the latest on the issue…

Recently, rumours have spread that there is little room for error when it comes to speed cameras. If it’s a 30 and you’re doing 31 mph, they say, prepare for an unwelcome letter in the post. 

It is unclear how such speculation has arisen. That it may have caused drivers to watch their speed more closely is a welcome side-effect. The truth, however, is a little different.

Speed camera tolerances: the truthSpeedcurb camera on Millbank in Westminster

Auto Express did some digging on the issue last year, including procuring figures from many of the UK’s police forces via freedom-of-information requests.

Consider the rumours about cameras with 1 mph tolerances, debunked.

Nearly all the forces that responded gave a 10 percent plus 2 mph threshold. That applies for both normal ‘Gatso’ style cameras, and any others that clock an individual speed case, as well as average speed check zones with multiple cameras over a distance.

Doing the maths, that means “safe” speeds could be as high as:

  • 79 mph in a 70 limit
  • 68 mph in a 60 limit
  • 57 mph in a 50 limit
  • 46 mph in a 40 limit
  • 35 mph in a 30 limit

Note the quote marks, though. Limits are limits for good reason that we shouldn’t need to explain at length – and a threshold doesn’t necessarily need always to be followed…

Curiously, two forces reported a 10 percent plus 3 mph threshold – Lancashire and the London Metropolitan Police. Add another mph to each of the above numbers.

According to Auto Express, the reasons given for this higher tolerance are to do with higher traffic numbers in London. In the case of Lancashire, it’s to give just that little bit more wiggle room.

Why is there such a wide margin for error in speed cameras?

Speed cameras UK

Error is just the word. Different cars show speeds to varying levels of accuracy. Some will show you’re doing 60 mph, when you’re actually going 57 mph. Construction and use regulations specify your speedo can over-read by 10 percent, but under-read by zero percent

The threshold is there so that drivers have no excuse if they’re caught. If you’re flashed, it’s more likely that you’re deliberately breaking the limit if you’re travelling at 80 mph, as opposed to 72 or 73. It serves both the interests of fairness and indeed, reduces workload for the justice system.

Every offence takes paperwork, they don’t just get your money for free, and that’s without factoring in offenders potentially appealing charges.

Wiggle room, therefore, serves both motorists and the authorities well.

PROOF that smart motorway cameras are always on

Smart motorway cameras always on

If you wanted proof that smart motorway speed cameras are always ON, even when the gantries are off, you’ve got it. Here are pictures of a Honda Integra Type R owner getting flashed under gantries that are ‘switched off’.

The driver was a customer of Tegiwa Imports. In a Facebook post, the company said “it’s the first time we’ve seen this happen. One of our good customers recently got busted by a speed camera (HADECS 3 type) on a smart motorway without a speed being displayed on the gantry!

“Luckily he wasn’t going too fast and only received a speed awareness course.”

Smart motorway cameras always on

As you can see, his speed was 82mph, so he was well above the legal motorway speed limit. That he got flashed by a camera would ordinarily come as no surprise.

What’s curious about this is the debate surrounding smart motorway cameras. Specifically, whether they operate when a speed, or any other sign, isn’t displayed on the smart gantries. Here is undeniable proof that they’re on.

Speed cameras in the UK: the truth

Speed cameras UK

We’ve previously published a piece taking apart the myth of smart motorway cameras, as well as details on exactly how speed cameras in the UK work. A few key points are worth repeating.

Treat all cameras as if they’re always on

To assume that a camera is off when the associated displays are on seems daft. A blank display doesn’t mean there are no limits in place, so why would the camera turn off? A word to the wise: treat any and all cameras as if they’re on.

Speed cameras UK

You won’t get tagged at 72

There was a rumour that motorway speed cameras would get you at 72. While you should always stick to prescribed speed limits, this isn’t the case. There is leniency based on discrepancies in indicated speed.

Tolerances – ten percent at most

The official line is that you should stick to prescribed speed limits. For those that don’t want to take that advice, heed our warning: you’ve got ten percent on top of the speed limit, with two or three miles per hour on. Our advice is stick to the ten percent if you must exceed the limits. That’s 55, 66, 77.

Like the gentleman in the 82mph Integra Type R, venture too far beyond and you’ll be made the example.

French speed cameras ‘much stricter’ than in the UK

French speed camera tolerances

How strict are French speed cameras? A new report claims speed limit tolerances in France are much tighter than in the UK.

Over here, 10 percent plus 2 mph is generally the permitted maximum before you see a flash in your rear-view mirror. But the AA says French cameras aren’t so lenient…

How tight are speed camera tolerances in France?

French speed camera tolerances

French cameras can be triggered when cars pass at just five percent over the limit. That means beyond 31 mph in a 30 mph zone, or 42 mph in a 40 mph zone.

At motorway speeds, you could ‘get away’ with 79 mph in the UK (although clearly this isn’t recommended). The equivalent in France is just 73 mph.

The AA surveyed nearly 20,000 of its members and found one-in-five weren’t aware of the tighter tolerances. It estimates that almost 800,000 British drivers could be fined for speeding in France by the end of the year.

Borders won’t protect you now, either. The MLA (Mutual Legal Assistance agreement) has been in effect since May 2017, requiring all EU members to share details on those who break driving laws in other countries with the appropriate authorities.

French speed cameras: what you need to know

French speed camera tolerances

  • There’s a five percent speed tolerance
  • They’re not painted in bright colours
  • There are signs to warn that they’re up ahead
  • If caught speeding, the fine WILL reach you
  • There are over 2,000 fixed cameras on French roads

“Year in and year out, UK holidaymakers driving abroad are advised to mug up on the road laws they are visiting,” said AA president, Edmund King.

“And now we know from official statistics that the French police are on a mission to chase up fines from British drivers before Brexit. Whether you’re driving in the UK or France, if you stay within the limit you’ll keep out of trouble.”