Motorway Speed Cameras - 86MPH?

DAnDan

DAnDan

DAnDan

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Before you ask, nope, this isn't an 'I've been caught, what should I do' thread, just a question I felt like asking.

Just after I'd passed my test a few years back, I was doing my pass plus course, and my instructor mentioned to me that motorway speed cameras (permanent ones, not mobile units) would never go off for anyone doing less than 86MPH.

I've never really put much thought into the truth about that, I assumed it was true at the time as I trusted my instructor fully and he knew his stuff. So I'm just wondering, is this true? Someone explained it to me as 70MPH +10% (accuracy of speedo) +10% (accuracy of camera) +2 (why not?), but that's just word of mouth style.

Either way, if anyone knows for sure, lets hear it. :p
 
Hmmm doesnt speedo inaccuraty overread rather than under read? So why would speed cameras take it into consideration

I always thought the speed camera rule was speed limit plus 10%
 
I always thought speed cameras would have you at anything over the limit? but then a copper seeing you at about 75 (within 10%) wouldnt even bother.
 
Eliot said:
Hmmm doesnt speedo inaccuraty overread rather than under read?

I always thought the speed camera rule was speed limit plus 10%
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That's what I've understood the limit as usually, but I just remembered being told the 86MPH figure. In my experience the speedos I've tested (assuming sat navs are more accurate) seem to underestimate speeds.
 
DAnDan said:
Before you ask, nope, this isn't an 'I've been caught, what should I do' thread, just a question I felt like asking.

Just after I'd passed my test a few years back, I was doing my pass plus course, and my instructor mentioned to me that motorway speed cameras (permanent ones, not mobile units) would never go off for anyone doing less than 86MPH.

I've never really put much thought into the truth about that, I assumed it was true at the time as I trusted my instructor fully and he knew his stuff. So I'm just wondering, is this true? Someone explained it to me as 70MPH +10% (accuracy of speedo) +10% (accuracy of camera) +2 (why not?), but that's just word of mouth style.

Either way, if anyone knows for sure, lets hear it. :p
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Not too sure where you would find a fixed speed camera on the motorway at the normal limit.

There are usually SPECs or GATSO cameras used in roadworks, and also on variable speed limit sections of motorway.

I would be happy to say you wouldnt get flashed for doing an indicated 75mph, however if I knew the camera was there, then I would go through it at an indicated 70mph on the speedo, be fool not to.
 
I thought the ones on the gantry's over the motorway, were only active when the speed limit sign changed from NSL to a lower speed?

I've tonked it past a few of them when they're on NSL and there hasn't been any consequences come my way.
 
Mucky_Pup said:
I thought the ones on the gantry's over the motorway, were only active when the speed limit sign changed from NSL to a lower speed?

I've tonked it past a few of them when they're on NSL and there hasn't been any consequences come my way.
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correct

the variable speed limit motorways (like the M25) the cameras are only active once the limit is reduced


Ther are no other fixed cameras on motorways anymore i believe, there used to be gatsos all along the M6 but they've all long since been removed.

You can get specs cameras, which are average speed at roadworks as well.

But apart from those, it would just be mobile vans or police officers with laser guns.

All of which will probably operate on ACPO guidelines of allowing you a true speed of 10% + 1 mph so 78mph is allowed. get a ticket at 79 (real) your speedo will most probably over-read so you can almost certainly get away with doing an indicated 80.

The 86mph comment is an old wives tale, about what speed police officers will pull you over for. It does hold a certain ammount of true, ive passed a marked car hid behind a bridge at a GPS 83 mph. This is enough to give me a ticket under ACPO guidelines but he didnt give a damn. Coppers dont generally. When i was caught for doing 100 + i said the copper i usually keep to low 80s - to which he commented that i should have been doing it that day, as most of them wont pull you over till you reach high 80s.

it is however not anything you should count on. He said "most" not all - and it would be just your look to be behind the copper who does give a ticket for 80mph. Strictly speaking, the ACPO guidelines are just that - guiidelines. An MP once got a ticket for 71mph on the motorway. They dont have to follow these guidelines and can issue a ticket for any infraction - however minor.

I however, have (since doing 100 +) always stuck to the low 80s and never had trouble.
 
DAnDan said:
That's what I've understood the limit as usually, but I just remembered being told the 86MPH figure. In my experience the speedos I've tested (assuming sat navs are more accurate) seem to underestimate speeds.
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That would be an offence since it is an offence to knowingly operate a defective vehicle.
UK legislation (same as EU in part) says that a speedometer must never under-read the vehicles speed. If it is under-reading either the speedometer is faulty or the overall tyre diameter has changed. Other than that UK legislation states that over-reads must not be more than 110% +6.25mph of actual speed between 25 and 70mph.
I was told APCO guidelines are 110% +1mph to prevent an enormous amount of tickets being issued (what and they arent already?)...but I guess it is a bit discretionary.....something that I detest :(
 
He is talking about the old-style Gatsos which had old-fashioned film inside. These were set very high so that the film lasted a reasonable time: if they were set to 78mph the film would have run by the end of the same day. The Tuvelos all had (IIRC) digital upload, so never run out. You should not assume it applies to them.



M
 
the minimum speed a camera on the motorway will go off is 79mph (70 + 10% + 2) this is because a speed camera or Talivan is unable to make any judgment as to aggravating circumstances and so they are set not to issue tickets below the "fixed penalty" limit
 
It's the average speed cameras that confuse me.

I ALWAYS stick to the 50mph limit on those things, in the left hand lane, while all the time watching people bomb past me on the right doing about 60mph!!!!

What do they know, that I don't?
 
physichull said:
It's the average speed cameras that confuse me.

I ALWAYS stick to the 50mph limit on those things, in the left hand lane, while all the time watching people bomb past me on the right doing about 60mph!!!!

What do they know, that I don't?
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They're probably all getting tickets!
 
physichull said:
It's the average speed cameras that confuse me.

I ALWAYS stick to the 50mph limit on those things, in the left hand lane, while all the time watching people bomb past me on the right doing about 60mph!!!!

What do they know, that I don't?
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Because you are probably doing a speedo indicated 50mph, which is in reality about 43-45 mph.

The guys who fly past, are really only going a few mph more, but are doing a true 50 rather than an indicated. (most likely).

This is why at average camera site you see the lorries "tanking" through, as their speedos are more accurate, so they are doing a true 50.
 
that has since been fixed.

THey had to, once it made national press.


TangoSixteen said:
Because you are probably doing a speedo indicated 50mph, which is in reality about 43-45 mph.

The guys who fly past, are really only going a few mph more, but are doing a true 50 rather than an indicated. (most likely).

This is why at average camera site you see the lorries "tanking" through, as their speedos are more accurate, so they are doing a true 50.
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No they're not

I sit at a GPS 53mph and see people flying by at 60 +
 
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