Safe Speed Forums

For reasons to do with the Cosine factor, speed cameras are almost never able to calculate the actual speed of a vehicle.Because the camera is usually at an angle to the vehicle,the Home Office states that the speed shown is actually less than the real speed. But they have no idea what the real speed is. This gives the Police a slight problem. They cannot very well state on the ticket:"we don't know what speed you were doing cos our fancy hi tech gadgets costing a fortune can't read the correct speed, we can only estimate your speed as ...mph." No, of course they can't say this. Even though this statement would be the truth. So they have to resort to subterfuge. They have replaced the statement "we don't know what speed you were doing"...etc with a euphemism. That euphemism is the term "Recorded Speed"!!! If they told the truth, eyebrows would be raised, uncomfortable questions asked. The public would wake up to the lie which is perpetrated by the authorities, ie.the camera is always right. So they use this Recorded Speed term to hide the literal truth, and most people are no wiser!!

Now, no doubt , say, a Traffic Officer or lawyer reading this would breezily dismiss my objection by saying that , yes, I am technically correct about the Cosine factor, but it's of no importance because the Police allow the ten percent plus three rule, so people are guilty anyway, bla bla bla.

The trouble is with this attitute is it's missing an important point.What do the Courts pride themselves on? Dealing in FACTS!!! A court isn't interested in rumour, innuendo, hearsay evidence, etc. It seeks only the TRUTH. How does it arrive at the truth? By rigorously examining facts, thus enabling justice to be dispensed!

Yet a CPS lawyer would always have to admit if asked, that he doesn't know the true speed of the vehicle. Recorded Speed is merely an estimation or assessment of actual speed!!! And that is the truth.So in a speeding case the courts thirst for this fact, the actual speed , is considered irrelevant. The lack of this fact can go right out the window. It doesn't matter! You can be convicted anyway, even though the prosecution don't know this crucial fact!

So called British justice?

This is true where cosine correction is applied, such as Gatso type cameras.
(Automated enforcement commences at 10%+2)

This cannot apply to any other type of camera as they will always underread because cosine correction is not applied; therefore the speed reading is always ‘in favour’ of the motorist (especially regarding graduated penalties). So for something like an LTI2020, the recorded speed will be no greater than the true travelling speed; hence a prosecution will be technically sound if an offending speed was detected (ignoring flaws such as slip error) – “Your recorded speed was 36 in a 30, so you must have been doing at least 36; we know you have committed an offence even if we’re not sure exactly what speed you were travelling at”.

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Views expressed are personal opinions and are not necessarily shared by the Safe Speed campaign

Welcome Zulu!

If you'll forgive me though, I can't help feeling that this argument smacks of desperation! Yes, of course you are "technically" correct, but as I understand it, the "crime" is "exceeding the speed limit". The "fact" that needs to be established, therefore, is whether or not you were doing so and not what your precise speed was. Even without cosine error, ANY measurement on ANYTHING will have finite accuracy. You could use the same argument to say that the "facts" couldn't be established because (for example) they couldn't say with total certainty whether your speed was 36.000000001MPH or 36.0000000006 MPH (and even if you could, you could continue the argument to infinity by moving the decimal point further along)!

I guess it would be a bit like a murder trial where the victim died after being stabbed 15 times - you wouldn't get the case dismissed if you proved that the victim was dead after the 12th stab!

I guess it’s the difference between accurate and precise. I suspect the real and recorded speed differential would be regarded as negligible for all practical purposes.

I don’t know where my neck becomes my head but for most practical purposes it doesn’t matter; I like your thinking though Zulu

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The views expressed in this post are personal opinions and do not necessarily represent the views of Safe Speed.
You will be branded a threat to society by going over a speed limit where it is safe to do so, and suffer the consequences of your actions in a way criminals do not, more so than someone who is a real threat to our society.

Hi. This is my reply to the three posters who kindly offered their thoughts on my "Recorded Speed" views. Especially to Steve, who seems to know a lot about the subject. What you say is quite correct, that the Law only has to prove you were exceeding the limit, not the actual speed you drove at. As far as it goes this is quite right. But what I am really trying to get at is this: for years the Police and the Home Office, and all the safe speed organizations who have zealously promoted and defended cameras, have repeated the mantra that the cameras are "accurate", or are viewed as such by the courts. This has been endlessly repeated so that everyone thinks it's true. Why not simply tell the truth, that the camera underreads, but that it doesn't matter? If this fact is so harmless, then why not reveal it? Over 30 million people in GB have a licence, yet next to none of them know the real truth about the matter. 30 million people think the cameras record the exact speed, which is why the authorities have such such an easy job getting 2 million people a year to plead guilty to speeding without ever having seen the evidence against them. A quite astonishing fact when you really think about it!!

Let's face it, if you got a letter from the Police telling you that you have been identified as a shoplifter in Asda, so we hereby invite you to plead guilty and pay this fine, well, would you? Or would you demand to know the evidence? Although I am perhaps getting slightly off the point here, I think you know what I mean.

My original point is valid cos if the truth about Recorded Speed was told (even though, as you say, it doesn't really matter legally), a lot more people would maybe start to question all of this and demand answers, which would cause the authorities a bit of a headache, and might lead to changes being made. As long as the status quo is kept, the Police are quite happy aren't they?

By the way there is one thing I don't understand, maybe you could please explain? How does the Gatso compensate for the Cosine factor?
Thanks.

Such a statement wouldn’t be strictly accurate (for cameras in general)
Some cameras can underread in certain situations, otherwise they are accurate (again dismissing the flaws).
I don’t think there has been any effort to conceal this; in these circles it is well known that the cosine effect is in favour of the motorist and is well understood by those who have researched it.


Perhaps you have answered your own question
IMO, this is a point is minor in the scheme of things.


I wouldn’t pay, but then again I’ve never shoplifted so I have cause to dispute it.
Those who know they are guilty may opt to pay that conditional offer instead of going to court and risking stiffer penalties.
Everyone, innocent or otherwise, should have the right to access all the evidence against them. This is an issue many supporters of this campaign are already concerned with (including myself: link 1, link 2).


Speed cameras are offset away from the travel of vehicles, which is sensible otherwise cars would crash into them
To allow cameras to be used at a usefully close distance to the targeted vehicles, they must be set at an angle to the traffic. For fixed Gatso installations (using cosine correction), that angle is mandated to be 20 degrees (a reasonable compromise) to the direction of vehicle travel (within the measurement area); this means they will underread.
Say the true travelling speed of a vehicle is 33.0mph, then the measured speed will be 33 cos (20) = 31.0mph

Gatsos multiply** the measured speed by 1/cos (20) = 6.4% and uses that as the recorded speed.
Say, measured speed = 31.0mph, then recorded speed = 33.0mph, which is more or less equal to the true travelling speed.
** I don't know how this adjustment is achieved (numerical calculation or simply fudging the sensor output).
This method isn’t without its flaws, such as bends in the road; other subtleties are the vertical axis cosine correction (as well as horizontal axis correction), and variance of cosine angle throughout enforcement area.


IMO: there are much bigger flaws to be concerned with. If anything is being concealed and misrepresented it is the issue of RTTM (link). To me this strongly suggests a level of wilful fraud on the part of the SCPs. So sink your teeth into that instead!

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Views expressed are personal opinions and are not necessarily shared by the Safe Speed campaign

Steve thank you very much. I never knew this! That's a bit more knowledge I have now picked up!