Traf Pol with a hand held camera.....?

Traf Pol with a hand held camera.....?

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gorvid

Original Poster:

22,250 posts

227 months

Monday 7th August 2006
quotequote all

Family member told me today that he went past a Traf Pol with a speed camera....
[standing in a layby]

60mph limit....possible speed up to 69 - definitely not 70.

What are the tolerences here [of both the device and the operator] ?
What is the likelyhood of points and a fine for this ?

Any other info?


BO55 VXR

4,373 posts

253 months

Monday 7th August 2006
quotequote all
If he didnt get pulled, then he's OK.. The gun is probably just a speed gun, not camera.

gorvid

Original Poster:

22,250 posts

227 months

Monday 7th August 2006
quotequote all
Sorry - I mean Speed Gun!!

do you mean he would have been pulled a the scene - not getting a nasty in the post ???

Edited by gorvid on Monday 7th August 21:39

Andrew D

968 posts

242 months

Monday 7th August 2006
quotequote all
Yeah, they need a load of gear to issue FPN's (video recorder et al).

The tolerences are typically limit + 10% + 2mph, so 68mph. It's because the officer has to "form a prior opinion of excess speed" before using the gun to confirm it. So in practice they use that margin so it would be difficult to contest that the victim was obviously speeding.

The guns are very acurate, despite what you might read in the Daily Hate and other tabloid rags. Car speedo's, however, are generally not acurate and over-read. So it's probably they were only doing 65mph-ish.

Besides which Trafpol (generally) don't try to stick the slightest infraction on anything that moves, they use common sense!

gorvid

Original Poster:

22,250 posts

227 months

Monday 7th August 2006
quotequote all
Good...

He's a very good and safe driver, and recently got his only ever 3 points after 40 years of driving
[Scamera hidden in a hedge in a country lane...]

He drives at fairly low speeds most of the time - and on this particular journey was passed by several much faster drivers...hence is rather bitter..

bluepolarbear

1,665 posts

248 months

Tuesday 8th August 2006
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Andrew D said:
The guns are very acurate, despite what you might read in the Daily Hate and other tabloid rags.


It is not the accurancy that is in doubt it is this the reliability / consistency of the readings.

Tafia

2,658 posts

250 months

Tuesday 8th August 2006
quotequote all
Andrew D said:
Yeah, they need a load of gear to issue FPN's (video recorder et al).

The tolerences are typically limit + 10% + 2mph, so 68mph. It's because the officer has to "form a prior opinion of excess speed" before using the gun to confirm it. So in practice they use that margin so it would be difficult to contest that the victim was obviously speeding.

The guns are very acurate, despite what you might read in the Daily Hate and other tabloid rags. Car speedo's, however, are generally not acurate and over-read. So it's probably they were only doing 65mph-ish.

Besides which Trafpol (generally) don't try to stick the slightest infraction on anything that moves, they use common sense!



Cops up up here don't always form a prior opinion. They seem to gun everything that moves. How do I know? I knew that a cop with a laser was over the brow of a hill in a 30 limit so crawled over the crest at 25.

Off goes my Bel 980............."Laser Alert". No prior opinion there, or perhaps he was so clueless he could not judge my speed to be less than 30 by a big margin. This has happened more than once.

I have also seen them hiding behind their cars in contravention of the ACPO Code of Practice ( not guidelines ),foreworded by Brunstrom who says it must be followed to the letter

Andrew D

968 posts

242 months

Tuesday 8th August 2006
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I have to say that I've yet to see a plot with a laser gun that isn't just constantly looking a the screen! Either they're reviewing a whole lot of footage, or they're using the device to help form a prior opinion!

smeggy

3,241 posts

241 months

Tuesday 8th August 2006
quotequote all
Andrew D said:
The guns are very acurate, despite what you might read in the Daily Hate and other tabloid rags.

If you are referring to Lidar guns (e.g. LTI 2020) then that’ll depend on your point of view.
Yes they can measure speed very accurately - but the speed of what?
It measures the rate of change of emitted light pulse flight times (and returned pulse width) - nothing more. Each pulse is bounced against a reflective surface but the equipment cannot know that the pulses are bounced from the same surface throughout the speed measurement. If the surface differs during the measurement in a manner resulting with a uniform rate of change of flight times, then a false speed reading will be achieved. This is called ‘slip’ and it’s an explainable and proven phenomenon.