Speed camera calibration

Okell

[Deleted User] said:

ontheroad1970 said:

maxmycardagain said:

My dashcam saved me, the ticket gave time, date and speed, the dashcam showed i was not yet in the 30, thier camera was detecting into the 60 before the 30 even started and i was doing 36(in the 60) then 28 in the 30....

That's where a dash cam CAN help, but you need the actual money shot to prove it, and you aren't likely to get that until you have turned down the out of court settlements.  Remember that the cameras have a range of 1000m and could get you before you have seen them since they are using very long lenses.

There is no way those cameras can be accurate at 1000m. Lasers diverge too much, and the simple radars in fixed ones diverge and can't discriminate at that range'''

Are you sure of that?  I thought the point of a laser was that it doesn't diverge - certainly not over a distance as short as 1000m.

Apparently we have 6 laser reflectors on the moon that are used to measure the distance of the moon from the earth, and each of those reflectors is significantly smaller than the frontal area of a car.  The Indian one has a diameter of 5.11cm.  (Or are you one of those people who don't think that we've been to the moon at all?).

List of retroreflectors on the Moon - Wikipedia

Five of the 6 operational reflectors were put in place between 1969 to 1973.  I think measuring the speed of a car 1000m away in 2024 should be a doddle.

FWIW I don't disagree with you that people should challenge speed measurements.  But they should only do so if (and only if) they are certain that they have virtually 100% infallible evidence that they were not speeding. 

I use a GPS watch multiple times a week when out running or cycling.  Having downloaded data from those runs and cycle rides I think they provide amazing information at an amazing level of detail.  But sometimes the maps show me running through houses and across gardens and through swimming pools that I know I haven't done.  I don't know how reliable it is.

I think the real difficulty anybody challenging the police case will have is when the police will produce an extrememly expensive expert witness who (1) explains clearly to the bench how the laser device works and why the speed measurement must have been correct, and (2) explains why the defendant's GPS argument is flawed.

Unless a defendant is both confident and knowledgeable enough about the physics to really put the police expert witness on the spot, I think they'd be backing a loser.

Okell

ontheroad1970 said:

[Deleted User] said:

I've explained this before. You ideally want two measurements to rely on, but even if you only have one, it's been established that you must have the possibility of challenging the police evidence.

And as we all know, the Home Office is far from infallible.

You can win, but you need strong evidence and a good defence.

In other words, it's a scam and the only safe thing to do is about 10 MPH under the limit, to offset errors in the police equipment.

You also need a very healthy bank balance if it goes wrong.  Unfortunately some here talk about this defence as if it is a slam dunk.  It's far from that, and people should be pragmatic, especially when they qualify for a course.  Remember the guy from Bristol who fought it on principle?  It cost him £75k.  He's not the only example.  

Are you thinking of this guy?  Man spends £30,000 fighting £100 speeding fine - BBC News

Not quite £75k but his kids' inheritance apparently...

And he was a retired engineer who presumably knew a bit about things like measurement error etc

He also had an expert witness who obviously didn't sway the bench