How do average speed cameras work in practice?

aliasojo

I understand they take a picture at point A, then again at point B and calculate between the two. If you've arrived at point B sooner than the calculation then you must have been speeding.

So does this mean the cameras will need to take a picture of every single car that passes them?

What happens if there is a cluster of cars/lorries passing at once on a dual carriageway? Will the cameras be able to pick up every number plate regardless?

Just idle curiosity. There's apparently going to be average speed cameras installed next summer on the main Scottish trunk route to the Highlands and I wondered how they would work in practice.

Cornucopia

They take a picture AND extract the number plates in real time. The cameras are normally set high up to allow for maximum coverage of vehicles traveling close together.

They can then track the vehicle's entry and exit time from the measured section of road, and determine the average speed.

It seems likely that trigger speeds for offences are set slightly higher with average speed systems compared to the traditional speed cameras to allow for inaccuracies in measuring what can be a long piece of road between the sample points.

DUTR

They use ANPR and take the reg of the passing vehicles , if the vehicle arrives at the camera too soon, then the rest of the process begins. Oh and all the changing lanes etc 'tricks' don't work, best to put the cruise control on and relax between the average speed zones.

DTDfanBoy

I wish more people would ask this question, one of my pet hates is the idiots that brake just before they reach these cameras :mad:

westwood68

When they recognise a number plate the computer stores the image at that point along with the recorded time.

If the system don't recognise a number plate, nothing is stored or recorded. Hence why bikes are immune to the system as long as the cameras are pointing at the front of the vehicle. I theory I could ride past on the bike at 100mph and the system wouldn't even recognise me. In practice I'd be done for dangerous riding/driving by the unmarked police car.

aliasojo

So a dirty mud caked number plate would do the same then? It would stop your plate form being recognised?

Seems a flawed system. I wonder if there will be many more dirty cars on the road next year.

keystone

aliasojo wrote: »

So a dirty mud caked number plate would do the same then? It would stop your plate form being recognised?

Seems a flawed system. I wonder if there will be many more dirty cars on the road next year.

Nope. Cameras are IR. Your legal plates are reflective. Camera sees straight through the dirt.

Cheers

aliasojo

keystone wrote: »

Nope. Cameras are IR. Your legal plates are reflective. Camera sees straight through the dirt.

Cheers

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

Moto2

Also, you never know which ones are being used
In a, say, 5 camera/ANPR section, No:1 may be used in conjunction with No:4 or they may use 4 and 5, or all of them or even none of them.

Ebe_Scrooge

It's actualy illegal to drive with number plates obscured. I remember once I was walking through town, there was a chap there using a scrunched up newspaper to wipe the mud off his number plates whilst a copper stood and watched - I assume the copper had pulled him over, and was lenient enough to let him off as long as he cleaned it there and then.

WTFH

westwood68 wrote: »

Hence why bikes are immune to the system as long as the cameras are pointing at the front of the vehicle.

In the roadworks on the southern section of the M25, some of the cameras are pointing at the rear plates.