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marduk

Speed Cameras On Overhead Signs

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This is something I've wondered but wasn't sure where to ask, so I thought someone here might know. I don't know if this is a new thing, but I only noticed it in the last year or so. Those big overhead signs that span the width of the entire road and have speed camera signs on them all have a camera pointing to every lane facing away from the traffic. Are they actually used and can the data be used to issue speeding tickets? I see people speeding past them all the time, whereas people tend to slow down if there's a regular camera or a van present.

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As far as I am aware, they only turn them on when there is a limit other than NSL in force.

Not that they couldn't turn them on whenever they wanted though...

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Been on the M9 a while too but you can see when the cameras are on the gantries, moral of the story is 'don't speed' or don't whinge if your caught and charged.

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They are called HADECS 3 and are to control variable limit roads.

Basically they work like the SPECS ones seen on the yellow posts in Average Speed zones (SPECS are calibrated to a fixed speed whereas HADECS 3 alter to match whatever speed is showing on the warning boards).

If you pass 2 cameras and they calculate that you took less time to do so than if you were at the posted speed you will get a ticket.

http://www.speedcamerasuk.com/hadecs-3.htm

http://www.speedcamerasuk.com/specs.htm

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Thanks, it was interesting to read more about them. I'm from the North East and I don't think we have many around here so that will be why I never really noticed them. Also just to clarify, I was only asking out of curiosity, not because I speed.

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I was told by a (now ex) RPU Copper from West Sussex that the cameras were set to 10mph over the posted limits

That's when they actually turned them on lol

I'm not advocating anyone tries it obviously lol

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I always assume that these things will catch you out, but I don't speed anyway so not really an issue for me.

If you pass 2 cameras and they calculate that you took less time to do so than if you were at the posted speed you will get a ticket.

So does that mean they check your speed at the point you go past and also your average speed between them? I wonder what happens if they speed limit changes, surely they couldn't expect you to lower your average speed until you get to the next gantry. There must be some compex software behind these things.

Not exactly, it's usually 10% to allow for inaccuracies in the calibration of car speedos.

And with most speedos over-reading anyway, you would have to be a bit silly to be caught out by these cameras anyway. If it's the usual "10% + 2" rule, then I'd have to be doing 85 by my speedo to get a ticket when it's a 70 limit.

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It's just 10% now, no other leeway.

The cameras save an image of your car as you pass the every camera and know the time you should pass the next one if at the limit.

If you pass earlier then it flags the system for a prosecution.

It can be quite possible to lose your licence within 5 cameras if you speed past them all.

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I have nothing to support my comment, but I'm sure I'd heard the 10% thing was dying out due to car speedometers being far more accurate nowadays.

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As far as I am aware, they only turn them on when there is a limit other than NSL in force.

Not that they couldn't turn them on whenever they wanted though...

 

Don't use that theory on the M42 around Birmingham; the cameras trigger even when the NSL (70MPH) is in force.

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I got caught by one of these on the M5 M4 almonsbury interchange, they went from one bored saying 50 to the next saying 40 and i went under the 40 at 47. I dont know weather it changed to quick or i just didnt notice but was a pain!

no i stick well below on my journey to and from work, but all too often see the mercs and beemers shooting through them and there is no flash.

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It can be quite possible to lose your licence within 5 cameras if you speed past them all.

Really? I always thought that if you were caught by several cameras that it was classed as once instance and you only received one speeding violation. Can't remember where I heard that, it was quite a while ago though.

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they have them on the M20, however, they use gatso's on the back of the sign. never a fan of average cams, but their general purpose by definition is much better than the premise of a speed trap.

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Really? I always thought that if you were caught by several cameras that it was classed as once instance and you only received one speeding violation. Can't remember where I heard that, it was quite a while ago though.

Technically you have contravened the speed limit 5 times on that patch of road, under five different monitoring points

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