How do average speed cameras work in practice?

Andy_L

aliasojo wrote: »

Didn't know that, learn something new etc etc......

and having a number plate that's illegible attracts a bigger punishment than the fixed penalty foe speeding

Moto2

spacey2012 wrote: »

Our number plate digits are much larger than is required by law, unless it has changed, when you see a bare legal plate on a motorcycle, they would need good resolution to read that.

Required sizes, car or bike

(except 'I' & '1')
Height 64mm
Width 44mm
Stroke 10mm
Space between characters 10mm
Space between groups 30mm
Top, side & bottom margin 11mm

westwood68

TrickyWicky wrote: »

You're talking an urban myth I'm afraid. If it doesn't recognise the plate number it simply flags it up for the operators attention where they can review the plate manually and put it into the system.

I'm guessing that's not totally accurate though; whilst I concede that the system may flag up number plates it cannot recognise and store the images, it must still recognise that something resembling a number plate has passed in order to flag it.

If a bike passes which has no number plate to sample and it's on a busy motorway, any current system is going to have a hard time picking it out to be stored and flagged for later manual scrutiny.

Does it automatically scan for something which looks like a vehicle and flag all those images anyway or it is specifically looking for number plates?

westwood68

Odd thing about bike number plates...they do have to be a set size with the correct font but whilst car number plates are checked on the MOT, bike number plates are not.

Can't think way not

spacey2012

Any system that is to be used in evidence in a sitting court in England has to be a VCA approved device if it records ANPR data.
Something parking scammers need pulling up on in front of district judges at county court.

Moto2

westwood68 wrote: »

Odd thing about bike number plates...they do have to be a set size with the correct font but whilst car number plates are checked on the MOT, bike number plates are not.

Can't think way not

There's no set size for motorbike number plates
As long as the letters and margins conform to the dimensions I listed above


EDIT: BTW, the number plate is part of the MOT test for bikes

TrickyWicky

westwood68 wrote: »

I'm guessing that's not totally accurate though; whilst I concede that the system may flag up number plates it cannot recognise and store the images, it must still recognise that something resembling a number plate has passed in order to flag it.

Yes. If it finds a plate then the next stage of the process will run. If not, it'll get flagged up.

westwood68 wrote: »

If a bike passes which has no number plate to sample and it's on a busy motorway, any current system is going to have a hard time picking it out to be stored and flagged for later manual scrutiny.

No not really. If there are loops in the road that detect vehicles going over, the camera gets triggered and then its off to processing. If no plate is found, flag it up.

What you also don't realise is that many ANPR average speed traps have cameras looking at both the front and rear of your car using cameras on the front and rear of the overhead gantry. Your myth of getting away with it on a motorcycle is pretty worthless to be honest. Many of the cameras have powerful zoom lenses too so they can detect you before you're even aware that they are there. This also allows them to see plates that might be partially covered at a close distance but visible from far (eg a ladder hanging over the back of a van).

westwood68 wrote: »

Does it automatically scan for something which looks like a vehicle and flag all those images anyway or it is specifically looking for number plates?

Depends. If you look at the demo program I linked to, it can run from a live video feed OR (as I've mentioned previously) the magnetic loops in the road can be used to trigger the camera at an exact point. Most of the ANPR systems I've looked at are loop triggered but not all on the highway are like that - some will just look for any change in the video stream and if detected OCR scan it for a plate number.

ahxcjb

neilmcl wrote: »

Is this actually true? I'm aware that they operate in pairs but I was under the impression they were consecutive pairs. Where's the evidence that they do as you say?

You're correct, and the OP is wrong. SPECS work in consecutive pairs. Often there is one lane that isn't being monitored (you won't know which it is), for example if there are 3 lanes, there need to be 3 cameras. If there are only two, you'll (probably) find one is monitoring the middle lane, and the other the outside lane. SPECS still, to the best of my knowledge, aren't Home Office type approved to operate outside of the pair function.

petermead83

Frustrated me that many people seem to go through faster than the speed limit being enforced. Guess they must brake really hard at the other end.

neilmcl

petermead83 wrote: »

Frustrated me that many people seem to go through faster than the speed limit being enforced. Guess they must brake really hard at the other end.

Depends, how much faster and how accurate (or otherwise) your speedo is.