albion1938:
How does the camera know you’ve a trailer on?
Bernard
Induction loops in the road surface detect a “large” vehicle, which allows the camera to be triggered at a lower speed. Typically this will result in all “large” vehicles being photographed at anything above 45mph (on a single carriageway National Speed Limit road). Manual processing of the photograph then allows the appropriate speed limit to be applied for trucks, buses, cars with trailers etc (with the DVLA database being used to differentiate between e.g. 7.5T and heavier vehicles).
Intriguing this! So, do the loops detect a large vehicle by the wheelbase, or the number of axles? What happens with, say, a Transit, which is subject to the national limit of 50mph on single carriageways, but similar dimensions to a large car which is subject to a 60 limit? Or is it not clever enough, and van drivers get away with it, while cars with trailers don’t?
Bernard
It’s not simply a case of counting axles or measuring the distance between them - although these are factors in the process. But you’re right - I don’t think it can differentiate between a transit van and a Merc S-class or Range Rover (although any of these pulling a trailer would trigger the lower speed threshold).
Nothing complicated - just a couple of wire loops buried in the Tarmac and a fairly simple bit of electronics to read the signals generated. It doesn’t have to be 100% accurate - all it is doing is switching the camera to a lower speed threshold for vehicles that might be subject to a lower speed limit. Humans are used to actually process the photos (and human beings are very complicated devices )
Im not sure if this will help or confuse the matter even more
This has been on here before.
You can just make out the 2 settings with a small ‘lorry’ type sign with the car sign below it and the 2 triggering speed settings in K/mh.
These do use doppler radar to trigger them.
Gembo:
Im not sure if this will help or confuse the matter even more
This has been on here before.
You can just make out the 2 settings with a small ‘lorry’ type sign with the car sign below it and the 2 triggering speed settings in K/mh.
These do use doppler radar to trigger them.0
I posted it ages ago, they use radar to detect the size of vehicle, a lorry will send more radar bounce back than a car, induction loops are used on red light cameras. Most cameras only have the yellow knob on the car setting, only a few have it on car and lorry as shown in the pic above
No chance of me getting done on that our motors are limited to 85kph when we got them since then they have been re done down to 83kph must be a fuel thing man does it feel slow on the motorways when every man and his dog apart from Sainsburys lol can pass you
Gembo:
Im not sure if this will help or confuse the matter even more
This has been on here before.
You can just make out the 2 settings with a small ‘lorry’ type sign with the car sign below it and the 2 triggering speed settings in K/mh.
These do use doppler radar to trigger them.0
I posted it ages ago, they use radar to detect the size of vehicle, a lorry will send more radar bounce back than a car, induction loops are used on red light cameras. Most cameras only have the yellow knob on the car setting, only a few have it on car and lorry as shown in the pic above
Yeah, i remember now, sorry mate, didnt mean to rob it as such, just thought it maybe beneficial to some in understanding what makes these scamera’s tic.
NewLad:
No chance of me getting done on that our motors are limited to 85kph when we got them since then they have been re done down to 83kph must be a fuel thing man does it feel slow on the motorways when every man and his dog apart from Sainsburys lol can pass you
You will if you go past one in a truck on a single at more than about 45 mph, provided its set up like the one in the pic! Dont ask me how I know this . I found that out in july 2008 and contributed to the Devon & Cornwall constabulary’s doughnut fund shortly after!
bubsy06:
they use radar to detect the size of vehicle, a lorry will send more radar bounce back than a car, induction loops are used on red light cameras.
Some of them certainly do use induction loops. This link goo.gl/maps/jXNB4 (assuming I’ve done it right) shows the camera on the A5 just a bit North of Nuneaton. You can clearly see the slots in the tarmac where the loops are buried.
This is the one that had me.
40 mph here FFS!
I knew about it long before but was miles away on the day in question, mind on other things. Its on a down grade and i rolled down by at a warp speed of 47 . maps.google.co.uk/maps?q=rosewo … 82,0,4.79
The one at Nuneaton got me. The really annoying thing is that, like it’s opposite number a little way along the road, it is supposedly enforcing the speed limit at that horrible staggered crossroads where the A444 crosses the A5. All well and good, and the camera is only about 300 metres from said junction - but the crossroads is on a dual carriageway section where a HGV can quite legally do 50mph anyway
Roymondo:
The one at Nuneaton got me. The really annoying thing is that, like it’s opposite number a little way along the road, it is supposedly enforcing the speed limit at that horrible staggered crossroads where the A444 crosses the A5. All well and good, and the camera is only about 300 metres from said junction - but the crossroads is on a dual carriageway section where a HGV can quite legally do 50mph anyway
Yeah, i see that, central divider = 50 mph at probably the more dangerous spot than where the camera is situated.
bubsy06:
they use radar to detect the size of vehicle, a lorry will send more radar bounce back than a car, induction loops are used on red light cameras.
Some of them certainly do use induction loops. This link goo.gl/maps/jXNB4 (assuming I’ve done it right) shows the camera on the A5 just a bit North of Nuneaton. You can clearly see the slots in the tarmac where the loops are buried.
The induction loop is just used as an on/off switch, it doesn’t detect speed or size of vehicle it only detects if a vehicle is present.
It is fitted so people who use radar detectors do not detect the camera until it is to late.
Radar detectors send out a signal to decipher changes in frequencies of electromagnetic waves, if the Gatso is off then there are no changes to detect, as the vehicle passes over the loop it activates the Gatso and by then it is too late for the detector to detect the changes.
bubsy06:
they use radar to detect the size of vehicle, a lorry will send more radar bounce back than a car, induction loops are used on red light cameras.
Some of them certainly do use induction loops. This link goo.gl/maps/jXNB4 (assuming I’ve done it right) shows the camera on the A5 just a bit North of Nuneaton. You can clearly see the slots in the tarmac where the loops are buried.
I’ve been through that one a little quick in a truck and it wasn’t triggered
bubsy06:
they use radar to detect the size of vehicle, a lorry will send more radar bounce back than a car, induction loops are used on red light cameras.
Some of them certainly do use induction loops. This link goo.gl/maps/jXNB4 (assuming I’ve done it right) shows the camera on the A5 just a bit North of Nuneaton. You can clearly see the slots in the tarmac where the loops are buried.
I’ve been through that one a little quick in a truck and it wasn’t triggered
)
