"A scientist is challenging his fine for speeding, citing the laws of physics.
Iain Fielden, who works at Sheffield Hallam University, was clocked travelling at 36mph in a 30mph zone by a speed camera in Huddersfield.
He argues that the reading was inaccurate because the camera is located on a bend in the road."
(from The Daily Telegraph:- tinyurl.com/2vlycq)
Technically, some truth in the matter, but I bet it won't affect the outcome! Note, he appears to be simply saying the reading is "inaccurate", which is a good enough defence.
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Perhaps he should keep quiet!
If the cameras work by radar (I don't know anything about them - do they work on radar?), then he was almost certainly going faster than the speed the radar measured. The shortest distance between 2 points being a straight line.
If the cameras simply take 2 pictures at a known time interval, and the markings on the road are used to determine speed, then he might argue that he was further towards the inside of the corner, and that meant he was actually travelling more slowly than the speed indicated by the markers in the centre of the lane imply - but if I read the article correctly, he isn't following this route.
Or, being a physicist, is he going to argue that relativistically, a straght line isn't always the smallest interval between two points?!
Number_Cruncher
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NC
They usually use inductive loops buried in the road; on a curve, he's got a point.
Either they are set parallel, or radially. Either way; they can't measure accurately along their whole length.
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I didn't think they were allowed to be installed on a bend as the Home Office issue rules about how they should be used when they give approval, and all the ones I have seen say on a straight stretch. etc..
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They're not rules any more - they're guidelines.. basically, they don't have to be followed at all. I can point out at least five cameras within a few miles of my house that break at least three of the placement guidelines. On top of that, the guidelines call for the cameras to be placed only until they've served their purpose and made that section of road 'safer' (debate for another day..) - how many ex-camera sites do you know of?
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Increadibly, I know of a site where they were removed from on both sides of the road, between Kidbrooke and Eltham on the A20. In 12 years of them being there I only witnessed 1 driver foolish enough to set these obvious cameras off, and that was a taxi driver (I was in his cab, it was a £20 fare!). Whether they took them out and put them somewhere less obvious is another matter.
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>>They usually use inductive loops
Do they actually use the data from the inductive loops as evidence?, or are the loops there to trigger the camera, the photos from which provide the evidence?
Number_Cruncher
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The speed reading must come from the loops; the timed camera shots just add visual "proof." [Are the road markings also on a curve?]
His point may be that the camera location is invalid under the guidelines - but is this an ongoing case that we can discuss?
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>>how many ex-camera sites do you know of?
I've seen a few charred and blackened that were probably ex-cameras ;>)
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Gatso uses radar, Truvelo uses inductive loops. The truvelo loops are inches aprt.
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thanks AE for clearing that
anomilee
anomiley
anomilie
that question up ,so now i know ,could never understand why i couldnt understand the lens systems on the truvelo,by the way were they named after a shirt i had to wear as a kid (trutex)
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>>how many ex-camera sites do you know of? I've seen a few charred and blackened that were probably ex-cameras ;>)
I know one camera was removed from Wakefield Road in Huddersfield a year or two ago - the markings are still there on the tarmac. All the others in the area are still there AFAIK.
The camera this thread refers to is definitely a radar-based Gatso, by the way.
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I would say this so-called physicist might be looking for a new job once this gets back to his employers. :-)
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How can the timing come from the loops-for legal reasons? That's OK if only one car is going through, on a dual carriageway there will, probably, be more than one. They must use the road marking. The loops are only used with moneytrons as far as I know-and haven't seen one go off-yet!.
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why didnt they put the speed camera before the bend ? thus ruling out calibration error and also making the bend safer to negotiate .... crikey it aint rocket science
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If the cameras work by radar (I don't know anything about them - do they work on radar?) then he was almost certainly going faster than the speed the radar measured.
It doesn't matter, if the measurement was "inaccurate".
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R v. Einstein (1902) is the stated case in question.
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>>if the measurement was "inaccurate".
All measurements are inaccurate. It's impossible to measure (anything!) without error.
Now, despite this doom and gloom, the real question is "is the measurement fit for purpose?".
If the physicist can show a mechanism whereby a motorist who is actually driving below the limt can be "done" by a camera system, then the camera system is in the wrong, and any people who have been "done" by it may have cause for complaint.
If however, the system is actually more lenient than required, why should that allow him to "get off"?
Number_Cruncher
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Whether Radar or Optical i.e. Laser speed scopes, the cosine error is in favour of the driver so a lower then actual speed is detected. Regards Peter
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Perhaps he's thinking that a bend introduces extra factors into the equation, like high-sided vehicles interfering with the result? Isn't it called slippage? If there's camera evidence, based on road markings, then it should be easy to confirm the actual speed.
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The guy's declaring this at an appeal court so I assume he fas done all the normal checks, slippage is basically a laser scope issue not a doppler radar issue. Regards Peter
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He is defending his case on legal points, not laws of physics, by that, I mean he won't try to show that he wasn't speeding, merely that the prosecution evidence cannot be relied upon. That's how the legal system works, and works for both prosecution and defence evidence.
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The thought has just occurred to me that he could also argue that by making a definite measurement of the car's position, Heisenberg's uncertainty principle introduces an inaccuracy* into the measurement of the car's speed.
* In fact, I think I might amble off and work it out. I'll report back on the result. :-)
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>>* In fact, I think I might amble off and work it out. I'll report back on the result. :-)
Interesting excercise - you'll find that Heisenberg can't help this hapless (and perhaps hopeless!) physicist!
Number_Cruncher
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Quick update on this one -
tinyurl.com/2e2827 {link to www.examiner.co.uk shortened}
Edited by Dynamic Dave on 14/01/2008 at 18:58
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Bliss in the US recently. Didn't see a single camera! Not even on the NYC subway! A no sleeping policemen. They were all wide awake.
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Errors in speed recordings caused by the vehicle not proceeding along the bore-sight of the radar, i.e. such as when a radar is sighted looking across a bend, are such that the equipment records a lower speed than would be measured along the direction the vehicle is traveling in. A practical demonstration can be given of this and there is theoretical reason for it. So he will need other factors to win his case, if the 'experts' know their stuff. Good reason not to sight on a bend is to do with inadvertent reflections.
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when a radar is sighted looking across a bend are such that the equipment records a lower speed than would be measured along the direction the vehicle is traveling in.
It doesn't matter - the reading is "inaccurate".
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FT: "It doesn't matter - the reading is "inaccurate"
Oh but it does matter. It is relevant.
A police car speedometer is also inaccurate (by about 1% or so). Indeed, to be pedantic, all equipment is inaccurate. So it is just a question of the extent of the inaccuracy.
You try telling a judge that the equipment recorded your speed as less than what you were actually doing and thus the charge should be dropped, and see how far you get. The prosecuting barrister, for one, will have a good laugh.
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tinyurl.com/6bvlbc
tinyurl.com/6g7w9m
"A university physicist who tried to dodge a £60 speeding fine has been ordered to pay £20,000.
Dr Iain Fielden, 41, spent £5,000 on experts to help him challenge Gatso evidence, after wife Vikki got three points and the fine for doing 36mph in a 30mph zone.
But he must now pay £15,000 costs after Huddersfield JPs dismissed his appeal, reports Metro."
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But, he's thinking of going to a higher court. Was it really worth it for 3 points and a £60 fine. Based on the articles appears he may be of the "I'm never wrong disposition", but could be wrong.
Wonder if after all the fuss about keeping a clean licence will now be selling the cars to pay for it? Won't get any more points though...
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"A university physicist who tried to dodge a £60 speeding fine has been ordered to pay £20 000.
A classic example of cutting off the nose to spite the face.
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