Had a letter today from Lincolnshire Police ...a notice of intended prosecution Apparently I went through a speed camera at 69MPH on a dual-carriageway. Now the speed limit on this dual-carriageway at this point is 70MPH....

So why have I got a NIP....because the camera/radar knew I was pulling a trailer (speed limit 60MPH) and took a photo. I presume it works on size of doppler radar return.

I was completely unaware that this technology existed in 'Safety' cameras (otherwise I'd have slowed down !). I googled it and it seems this one camera on the A1 southbound at Great Ponton is the only one (how lucky!) but it might not be.

So gone are the days of setting the cruise at 70MPH with the trailer on the back....needs to be 67MPH !

All the people I know who race/trailer things......be careful out there.

I think this came in about 10-12 years ago, so they could catch wagons speeding, the first one I knew of was on the M4 near Port Talbot.

That's going to slow me down then

Thanks for the tip.

Yup someone on RHOCAR last week got the same in an artic

Andi

I presume they photograph anything larger than a car and then look at the pictures to see if it is a coach/van/artic/car&trailer and so on.

I thought there was some cameras with Automatic number plate recognition ability to link vehicle type like lorry or vans with different speed limits and also rumored on a local road with history of multiple road deaths where they manually review the trigger pictures for caravans and trailers and then prosecute against the lower limit

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Originally posted by jeffw
I presume they photograph anything larger than a car and then look at the pictures to see if it is a coach/van/artic/car&trailer and so on.

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Well...when I used to maintain and operate Radar systems in the RN it was pretty obvious from the size of the return that something large was being pinged, but you may have more experience of Doppler radars than I do..

And no....the yellow box wasn't a manned unit.

[Edited on 28/6/14 by jeffw]

When I worked police radar the machine would lock on a city bus doing 40 km/h and not even see a speeding motorcycle passing the bus doing 80 in a 60 km/h zone.

Size does matter with radar.

Not so with laser the little red dot goes on the vehicle you want to look at.

So, why go through at 69mph when the speed limit is 60mph?

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Originally posted by jeffw
Well...when I used to maintain and operate Radar systems in the RN it was pretty obvious from the size of the return that something large was being pinged, but you may have more experience of Doppler radars than I do..

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I think you are possibly over analysing. Why not temporally set the limit to 60mph of the speed detector, look at all the images of vehicles (manually) that are committing a prosecutable offence then discard the other images. Tedious but possible.

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Originally posted by coozer
So, why go through at 69mph when the speed limit is 60mph?

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interesting - my understanding, and it may well be wrong, is the strength of the return is proportional to the area of the object (not its length as I assume the radar is facing the rear of the vehicle - I would imagine that a trailer with a 7 kit car on top would give a similar signal to the towing car - a covered box trailer would give a much larger signal.

A manuall process does not sound practical as I cannot image someone sifting through images of vehicles going at 10 mph less than the speed limit to figure out if they are pulling trailers, maybe the technology is there to do this???

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My understanding of these scammera's is that the beam travels up and down and measures the height to see if the vehicle is high, ie a truck. Didn't think this applied to trailers but maybe it triggered because it was low? Then some one at the centre rubbing his hands see's its a trailer.

I got flashed on a single carriageway many years ago at 45mph driving a rigid lorry. Now I always ensure I'm under the appropriate speed limit around these places.

Shame the technology doesn't exist to catch speeding caravan drivers overtaking in the outside lane.

Just had another read of your first post there, you say the dual carriageway speed is 70mph. Its not, its national speed limit so with a trailer, of any kind its 60mph, and white van mans speed is 60mph as well (if the van is over 2t GVW) And is 50 for a truck, 30 for a git big load with an escort even slower for wide loads, the list of speed limits is quite large...

[Edited on 28/6/14 by coozer]

Or catch lorry drivers spending 10miles overtaking each other on a dual carriageway with a speed differential of less than 1mph. Everyone has their pet motoring hates, when I am towing it is muppets sitting in the middle lane at less than 60mph....

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Originally posted by jeffw
when I am towing it is muppets sitting in the middle lane at less than 60mph....

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The number of people I see towing at a frighteningly high speed is remarkable. Seems very few have had to make evasive action and seen how towing a trailer really messes with that ability at speed. The lower limit is there for a reason.

Not trying to be smug, just saying drive to conditions, and rarely do the conditions of towing work with driving fast.

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Originally posted by jeffw

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Originally posted by coozer
So, why go through at 69mph when the speed limit is 60mph?

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Let me think about that for a moment.....I guess for the same reason that any of us speed really.

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interesting - my understanding, and it may well be wrong, is the strength of the return is proportional to the area of the object (not its length as I assume the radar is facing the rear of the vehicle - I would imagine that a trailer with a 7 kit car on top would give a similar signal to the towing car - a covered box trailer would give a much larger signal.

A manuall process does not sound practical as I cannot image someone sifting through images of vehicles going at 10 mph less than the speed limit to figure out if they are pulling trailers, maybe the technology is there to do this???

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I presume (and don't have any technical specs to back this up) that it is a relatively high frequency low strength system. When a car and trailer go through the beam it will present a larger return from the rear 3/4. The trick here will be to set the system to trigger when a large return is doing more than, say. 60mph. That will then enable you to manual review the images/data and ascertain if it is a Lorry or car & trailer and apply the correct limits/send out the NIP.

Please don't think I'm suggesting that I wasn't doing anything wrong here....just trying to alert other people who tow who also may 'drift' over the limit on occasions. 9 mph over the limit isn't really the crime of the century either.

[Edited on 28/6/14 by jeffw]

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Originally posted by chrism
They should just make undertaking legal like in some other countries.

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Originally posted by coyoteboy
The number of people I see towing at a frighteningly high speed is remarkable. Seems very few have had to make evasive action and seen how towing a trailer really messes with that ability at speed. The lower limit is there for a reason.

Not trying to be smug, just saying drive to conditions, and rarely do the conditions of towing work with driving fast.

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Originally posted by bi22le

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Originally posted by jeffw

I presume (and don't have any technical specs to back this up) that it is a relatively high frequency low strength system. When a car and trailer go through the beam it will present a larger return from the rear 3/4. The trick here will be to set the system to trigger when a large return is doing more than, say. 60mph. [bold]That will then enable you to manual review the images/data and ascertain if it is a Lorry or car & trailer and apply the correct limits/send out the NIP[/bold]

Please don't think I'm suggesting that I wasn't doing anything wrong here....just trying to alert other people who tow who also may 'drift' over the limit on occasions. 9 mph over the limit isn't really the crime of the century either.

[Edited on 28/6/14 by jeffw]

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my knowledge is little more than a good education and being an proper engineer (not just chuck it in my title for fun and profit), not radar related. The modern units may have this tech but would have to be backed up by human approval, surely. I know they don't send most tickets out with a human check but this is quite specific. I take it thay pulled the common illegal stunt of providing no evidence and threatening you with additional costs or Court if you want proof?

It sounds like this is your specialism, can they fit intelligent emitters and receivers in these small yellow boxes that would capture this sort of detail? Considering the market and associated cost I just don't see it.

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Originally posted by chrism

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Originally posted by jeffw
when I am towing it is muppets sitting in the middle lane at less than 60mph....

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They should just make undertaking legal like in some other countries.

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Jeff I'm sure I told you to watch out for that at the Christmas doo. I got done for exactly the same thing. Same speed same road trailer on back!

Apparently gatsos can enforce three different speed limits depending on the vehicle size

Don't remember you mentioning Ash....lesson learnt though...

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Originally posted by morcus

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Originally posted by chrism
They should just make undertaking legal like in some other countries.

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It's not illegal to pass someone in the middle lane while your in the first lane. It only gets dodgy if your changing lanes to do it.

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It's not illegal to pass someone in the middle lane while your in the first lane. It only gets dodgy if your changing lanes to do it.

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I think there's a bit of over thinking with the cameras. Sure the older ones might have to do some trickery with detection to figure out when to take a photo or not (mainly so they don't run out of film taking pictures of squirrels or similar). But the modern cameras take photos of EVERY vehicle that goes past them, and then the software figures out later whether to bin the photo or do something with it.

Writing clever software is infinitely cheaper (and easier to maintain) than having clever radar detectors that would require regular calibration to be enforceable.

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Originally posted by omega 24 v6

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It's not illegal to pass someone in the middle lane while your in the first lane. It only gets dodgy if your changing lanes to do it.

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Interesing???? Can you justify that with any links?? My understanding is you can only undertake IF the car in the outsde lane is signalling to turn right. In town this is difficult as most people will stick in the right lane for any future turns coming up. BUT at speed on a 3 lane or more motorway I do not think you will get away with undertaking EVER.
Again the middle and outside lanes are for overtaking only. And i agree with the other poster when they say prosecute the lane huggers.

On the original topic Years ago I found out that when the van/trailer combination when the race car was loaded to far forward on the trailer then it would trigger the cameras. Looks like you just been unlucky maybe.

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I'll look for a link later but I was taught that by BSM andI believe its in the highway code. Basically if the traffic is moving slower in the other lane your allowed to pass it. from what I understand its in no way illegal to sit in the first lane and maintain a constant speed to pass things in other lanes.

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Not Quite. You can undertake if on a motorway filter lane. Either coming on or off of the motorway. If the lines are short with small gaps it signifys a separate lane that has no association with other traffic.

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A fellow competitor towing a BJ Shuttle behind a LWB Transit was telling me that he was 'flashed' by an overhead gantry camera on the M25. Would've been somewhere on the NE section, before his chosen Lydden exit.

He was asking the same question - how did the camera 'know' he was towing. His speed overshoot would've have been excessive, but the nonetheless greater than the 60 mph allowable. So there you go, it IS happening, but how and why... I don't know.

A question though to those who know - are the cameras triggerable by a remote operator????????
What I mean is, if the operator is looking at the M25 traffic on a screen, can they tell the camera to trigger (i.e flash) for a specific vehicle passing underneath it for a sub-70mph class limited vehicle.

All this is yet another reason to stay with my 75 BHP Transit, where towing keeps things around the class limit unless it's a long downhill section! Plus, yet another reason to keep the kit car off the road, it's just too legislational out there.

Just a point but a true 68 mph is likely to be 72 to 74 mph on the speedo that is perhaps just a wee bit too fast for comfort with car carrying trailer?

Never had a problem in Europe at 80ish so 70 never seemed an issue here. Obviously it is speeding and I've been nicked but not really an issue with a light car on a twin axle trailer behind the XF.

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Originally posted by motorcycle_mayhem
A fellow competitor towing a BJ Shuttle behind a LWB Transit was telling me that he was 'flashed' by an overhead gantry camera on the M25. Would've been somewhere on the NE section, before his chosen Lydden exit.

He was asking the same question - how did the camera 'know' he was towing. His speed overshoot would've have been excessive, but the nonetheless greater than the 60 mph allowable. So there you go, it IS happening, but how and why... I don't know.

A question though to those who know - are the cameras triggerable by a remote operator????????
What I mean is, if the operator is looking at the M25 traffic on a screen, can they tell the camera to trigger (i.e flash) for a specific vehicle passing underneath it for a sub-70mph class limited vehicle.

All this is yet another reason to stay with my 75 BHP Transit, where towing keeps things around the class limit unless it's a long downhill section! Plus, yet another reason to keep the kit car off the road, it's just too legislational out there.

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I've always been very careful when towing, firstly because I lost control once and it was fooking alarming, and secondly because I don't have category E and don't fancy getting my collar felt!

If anyone is interest, this is how it is done

The Gatsometer radar speed camera system, as approved by the Home Office for use in the UK, is based on a continuous wave (cw) radar where the rate of change of distance between the radar and its target is obtained from the change in frequency of the returned signal. This change in frequency is known as the Doppler effect.

The beam from the Gatsometer Type 24 radar has a width of 5 degrees that is directed across the path of traffic at an angle of 20 degrees with respect to the kerb. The field of view of the camera includes the area of the radar beam. The frequency of the radar is 24.110 GHz and the change in frequency that results from a moving vehicle passing through the beam is 67.75 Hz per mph of the vehicle.

As a vehicle enters the beam, Doppler shifted returns are received. When 3 consecutive speed measurements have been made, that exceed 20 Km/h and are within ±1 km/h, then the system begins to build a speed histogram. Speed measurements end when a Doppler signal has not been received for 20 milliseconds i.e. the vehicle has left the beam. The total number of speed measurements made by the system depends on the length of the vehicle. For a saloon car this is typically 400 to 500.

If the system determines that an offence has been committed, as defined by the vehicle exceeding a pre-set speed threshold, a photograph sequence is initiated that comprises of two photographs taken at a pre-set time interval. The radar speed measurement is given in the data blocks superimposed on the photographs during the film at the time of the offence.

Together, the two photographs provide the secondary evidence of a vehicle's speed. The distance travelled during the time interval is estimated from road markings at a known spacing. The secondary speed measurement then becomes a matter of distance/time which must be within 10% of the primary evidence. The time interval between photographs, typically 0.5 to 0.7 seconds, is derived from a timing source that is standalone. Therefore the resulting speed estimate is independent of that measured by the radar.

hmm can't see how a camera could work out the difference between a large box van and a car towing a trailer, even a Rangerover is the size of a caravan. Given the range of sizes, weight’s, axles and types of trailer it would be impossible to make a camera that could tell the difference.

If you set it to 60mph and manually went through them you'd be there all day given the number of vehicles it would photograph on a busy motorway

I suspect you were in a temporary 60mph zone, there’s plenty of those around and sometimes hard to spot in heavy traffic or you were caught on a police held radar gun or you were not the only one speeding at the time and hence got caught in someone elses picture...

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hmm can't see how a camera could work out the difference between a large box van and a car towing a trailer, even a Rangerover is the size of a caravan. Given the range of sizes, weight’s, axles and types of trailer it would be impossible to make a camera that could tell the difference.

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given that google image search allows you to enter a picture and it will find similar images on the web, could they not have an image search of sorts with standard trailer/van/lorry templates set up to spot similar vehicles?

this would at least allow them to significantly reduce the number of likely candidates that would need a human to make an actual decision on?

Paul

[Edited on 30/6/14 by swanny]

I stand by my last view that you were not the only person speeding in the photo and have just been unlucky, probably blame the guy overtaking you who triggered the camera, which is probably quite an easy way to get caught when towing.

I mind watching a tv program showing a policeman checking two photo’s on a computer from a speed camera (hence the two flashes you see) simply measuring the distance each vehicle had moved in the two frames, it really was that basic, but anyone in the shot who was over the limit was done and most cameras are set to take a picture of all lanes in the one shot.

Dual carriageway...NSL, not temp speed limits. Wouldn't be that difficult to set a speed of 67MPH on the system for vehicles that larger than X (car plus trailer is up in the 25-30+ ft mark). Then you only have to sift through the photos on a screen and nick the obvious offenders (me in this case). Probable takes one person less than 1/2 per day.

[Edited on 30/6/14 by jeffw]

I take it you never had a blow out on the trailer, or had to stop suddenly like I have.

Otherwise, you would know why the lower limit and would not tow at those dangerous speeds.

Luckily for me the blow out was at very slow speed but enough to ensure that these days I always have good new tyres and NEVER exceed the towing limits (weight or speed).

I must see at least a couple of totalled caravans of trailers in their sides each year, don't fancy joining them.

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Originally posted by K13JOB
I take it you never had a blow out on the trailer, or had to stop suddenly like I have.

Otherwise, you would know why the lower limit and would not tow at those dangerous speeds.

Luckily for me the blow out was at very slow speed but enough to ensure that these days I always have good new tyres and NEVER exceed the towing limits (weight or speed).

I must see at least a couple of totalled caravans of trailers in their sides each year, don't fancy joining them.

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Originally posted by Mr Whippy
hmm can't see how a camera could work out the difference between a large box van and a car towing a trailer, even a Rangerover is the size of a caravan. Given the range of sizes, weight’s, axles and types of trailer it would be impossible to make a camera that could tell the difference.

If you set it to 60mph and manually went through them you'd be there all day given the number of vehicles it would photograph on a busy motorway

I suspect you were in a temporary 60mph zone, there’s plenty of those around and sometimes hard to spot in heavy traffic or you were caught on a police held radar gun or you were not the only one speeding at the time and hence got caught in someone elses picture...

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I was recently conversing with one of the guys trialling some 'extras' in the speed cameras in Lincolnshire. They have been using them (for several months now) with imaging software that can tell automatically if you are eating, smoking, using a phone, tailgating, etc (I don't know the full range), so I would expect this is a fallout of the tailgating detection thing - two object very close together and moving at the same speed? Apparently the software is right 'high 90%s" of the time in detecting these things. At the moment they are not allowed to use it for fining you for using your mobile etc, but I'm pretty sure that will come soon(ish). Tailgating I actually quite welcome - as long as it detected that you had just pulled out behind a faster car that had just overtaken you.
Be careful out there
Regards
Hugh