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Author: Subject: Speed Cameras that know you are pulling a trailer
omega 24 v6

posted on 29/6/14 at 09:47 AM Reply With Quote
quote:

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.



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.





If it looks wrong it probably is wrong.

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Slimy38

posted on 29/6/14 at 10:00 AM Reply With Quote
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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bi22le

posted on 29/6/14 at 10:37 AM Reply With Quote
quote:
Originally posted by omega 24 v6
quote:

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.



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.


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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morcus

posted on 29/6/14 at 10:49 AM Reply With Quote
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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omega 24 v6

posted on 29/6/14 at 11:45 AM Reply With Quote
quote:

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.



Quite agree. Always wary of late lane changers who don't check mirrors or you are in the blind spot.





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motorcycle_mayhem

posted on 29/6/14 at 03:50 PM Reply With Quote
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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britishtrident

posted on 29/6/14 at 04:18 PM Reply With Quote
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?





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jeffw

posted on 29/6/14 at 05:07 PM Reply With Quote
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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jeffw

posted on 29/6/14 at 05:09 PM Reply With Quote
quote:
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.


M25 between junction 10 and 5 have new camera systems which seemed to be operating all the time so anything over 77mph and you are puilled. Wouldn't be surprised if the same was true of trailers/artics etc.






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JoelP

posted on 29/6/14 at 07:36 PM Reply With Quote
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!





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jeffw

posted on 30/6/14 at 08:58 AM Reply With Quote
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.






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Mr Whippy

posted on 30/6/14 at 11:04 AM Reply With Quote
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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coyoteboy

posted on 30/6/14 at 12:31 PM Reply With Quote
quote:

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.



I suspect van/car combinations are not very well defined, but trailers make a car MUCH longer, at which point it puts it WAY outside any car value and makes a "towing too fast" really the only likely answer, and if they're wrong (because you drive a stretched limo) they'll just cancel the ticket.






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swanny

posted on 30/6/14 at 01:12 PM Reply With Quote
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]

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Mr Whippy

posted on 30/6/14 at 01:59 PM Reply With Quote
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.

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jeffw

posted on 30/6/14 at 02:11 PM Reply With Quote
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]






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K13JOB

posted on 30/6/14 at 05:48 PM Reply With Quote
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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Mr Whippy

posted on 1/7/14 at 06:28 AM Reply With Quote
quote:
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.


You’re absolutely correct about the tyres, tbh it's my main concern when towing our caravan as they always seem to get much much hotter than the cars even after careful checking of the pressures beforehand (49psi which is surprisingly high really as my cars only 34psi) and there’s a big difference between 50mph (warm) and 70mph (too hot to touch the tread) on how hot they get. I think our next caravan is going to be a twin axle just for that very reason.

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onenastyviper

posted on 1/7/14 at 06:49 AM Reply With Quote
quote:
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...


It may have something to do with RADAR cross-section of different vehicles - i.e. the amount of signal that returns to the receiver?





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hughpinder

posted on 1/7/14 at 08:16 AM Reply With Quote
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

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