Safe Speed Forums

Haven't a link but the scam with regards to the LTi.2020 has broken front page news in todays Daily mail. I'll try and post a link if there is one.

I've read the news paper and it a cracking piece (full 2 pages), and once more it was the British model they tested. It even clocked a cyclist travelling at about 5mph doing 66mph (Like to see Mr SC's lot now). How can they be allowed to continue using such a useless piece of junk? And nice to see Paul got a mention .

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Useless laws weaken necessary laws.

Yeah, I read that today - absolutely shocking. It amazes me that they can get away with ruining people's lives with a peice of unreliable equipment. The wall doing 44mph says it all...

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Science won over religion when they started installing lightning rods on churches.

I just found a problem since joining these forums; I find that I have to repeat myself a lot.


Me from PH:

Unfortunately, in the eyes of the so-called 'expert witness' (I know much more about these guns than he does) there is a flaw in the newspaper report. He has already admitted that you can get false readings from stationary targets but the software can somehow differentiate between stationary and moving targets (this of course being total bull).

The 66MPH cyclist simply does not work because there’s no point (or set of points that when swept) can indicate and maintain 66MPH for 0.3 seconds (8.6 meters), hence I reckon the beam missed it and swept across something else (stationary!!!) instead. However, even though that particular test is definitely invalid, who can say that these measurements on motor vehicles are not also invalid!


I plan to email Sue Reid to tell her how the tests should have been done.

Presumably you mean they should have been conducted under the cloak of a big Home Office Secret Squirrel Circle-Jerk so that noone could ever find out about it.

That's how it's usually done.

Despite the very valid point made by Smeggy, a very eye opening article.

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Semper in excreta, nur quantitat variat.

Yes it does work.

If a laser gun was misaligned, then if it were targeted at a bicycle and tracked, the laser would end up tracking something else. A completely duff speeed reading would be obtained.

The parallax between red dot and eye could be enough to produce this, with the laser beam going through the bicycle and striking the wall beyond.

You will have no doubt seen the Inside Out program where a forwards moving car was shown as travelling backwards - probably caused by misalignment.

The assumption you made here was that the laser slipped on the bicycle. Clearly it did not.

And there are more problems with the LTI 20.20 than just slip. Reflection and beam pattern also give rise to issues.

Let me just explain what that means in case some of our readers don't know.

The LTI2020 sends an invisible infra-red laser beam that's used for making the measurements. But the operator needs to know exactly what the beam is (supposed to be?) hitting. So the operator looks through an optical sight with a cross hair to identify the laser target point.

These two systems have to be aligned to aim at the same point, and the gun provides adjustments to enable this to be done. Operators are supposed to verify the alignment in two planes before use. This is commonly done by measuring the distance to a vertical pole with the gun held normally and also held at 90 degrees (i.e. 'on its side'.).

The single complete traffic video that's available to the public apparently contains a serious optical misalignment - when the cross hairs are on one vehicle the laser is apparently actually measuring the speed of another object.

Just one more reason for calling it the 'dodgyscope'.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Clearly I did not.

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

Due to several articles published in the Daily Newspapers, where speeding motorist have been wrongly convicted of speeding which involved the use of the LTi 20-20 speed gun, and that they appear to give false reading, it has brought about much controversy as to their accuracy. There have now been two attempts by two different organisations to prove the Lti 20-20 is flawed. On both occasions it has been shown that LTi 20-20 can give sporadic readings. I am not an Electronics Engineer so I can only evaluate what I’m being shown on both the TV, and in the Daily News papers. Until the Home Office is prepared to join up with "who ever it takes", I will continue to believe that the LTi 20-20 is flawed, because nobody has shown me otherwise. The very fact our Government/SCP’s have evaded the offer to prove the LTi 20-20 is not flawed. - Well speaks for itself IMO.

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Useless laws weaken necessary laws.

Then this:


is a totally incorrect conclusion to draw, surely?



This statement is definitely FALSE. Clearly the laser has found a set of points that give a speed of 66mph right?

So how, without any information as to where the laser beam has actually struck, you appear to have drawn the conclusion that:





How have you done that?

Your conclusion can only be a correct conclusion, if (and only if) it was claimed the 66mph reading came from slip on the bike. I see no such claim, and even then you'd be wrong, because the slip would require an extra 61mph - not 66mph. Remember the bicycle was said to be travelling at 5mph in the first place (keeping aside such complexities of angles for the time being).

You negelcted to document (or even think about) the numerous other possibilities. Here are some.

(1) The laser was aimed at the bicycle but due to misalignment hit an object that was moving at 66mph.

(2) The laser was aimed at the bicyle but due to beam spread, an abject that was moving at 66mph intercepted the beam and was read instead.

(3) The laser beam was aimed at the bicyle but was reflected onwards to a secondary target which gave a reading of 66mph.

(4), (5), (6) As for (1), (2) and (3) but with slip effect added to the speed of the secondary target.

The only context in which your comment about the test being invalid sort of makes sense would be if it were claimed the reading was a slip reading from the bike. Now you are saying you did not make this assumption, in which case I fail to make sense of your original post at all.

Maybe you should explain:



in more detail.

Let me jump in here and defuse the confusion.

I'm perfectly satisfied that Smeggy correctly identified the bicycle test as 'misleading' and therefore invalid in terms of conclusions. There was no slip effect on the bicycle and the speed reading came from elsewhere.

There's nothing to argue about here so please let's move on.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Hi Blackdouglas.

TBH, I thought I gave enough detail, perhaps my description wasn’t clear enough, perhaps you misunderstood me; other people on another forum appeared to understand the same text. It appears that you completely overlooked the subtleties buried in my text.

I did indeed consider all those points you mentioned.

(1) The laser was aimed at the bicycle but due to misalignment hit an object that was moving at 66mph.

Hence my comment of “beam missed it and swept across something else” (don’t forget, the monitored surface may not have been moving).

(2) The laser was aimed at the bicyle but due to beam spread, an abject that was moving at 66mph intercepted the beam and was read instead.

Hence my numerous exclamation marks after “(stationary!!!)”

(3) The laser beam was aimed at the bicyle but was reflected onwards to a secondary target which gave a reading of 66mph.

It’s well beyond chance that the gun will accept the secondary pulse reflected from the bike via a secondary surface, given that the primary reflection directly from the bike will be: earlier, stronger, (and most importantly) from the correct position.

There is no possible way you can achieve a non-erroneous slip reading from a push-bike, especially an extra 61mph (which is my original point, for reasons already stated).

Perhaps I should have said “The 66MPH cyclist simply does not work because there’s no point (or set of points that when swept) on the bike can indicate and maintain 66MPH for 0.3 seconds (8.6 meters)”, but I thought that was obvious.

I said “invalid” in the context that the tester certainly did not get a sweep result from the bike, given that they claimed to have done, hence my comment of “who can say that these measurements on motor vehicles are not also invalid!”.

You can argue semantics as much as you want, but I stand by my original post

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

Apologies, I only just noticed your post.
BD, I'll be happy to continue this offline if you wish.

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

Perfectly understandable. No problem at all.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

I guess now if the LTi20.20 is as reliable as Mr Garratt indicates, that'll we'll be seeing legal action again the Daily Mail, will be interesting to see.

Why is it misleading? And why is it "invalid in terms of conclusions"?




Clearly there is. I disagree with both Smeggy and yourself, and having an adult discussion about it ought to be what these forums are about. It's not as if we've got a flame war going on here - we simply have two posters exchanging a difference of opinion - in my case I am trying to get to the bottom of what it is Smeggy (and now you) are trying to say. I'm very sorry, but I am surprised by your intervention. I find it similar to the "Home Office" saying "there's nothing wrong with these devices so let's move on". Expressing an opinion and then telling those that disagree to "shut up" seems to me a bit ironic given the subject matter.

I believe that obtaining a speed reading of 66mph when supposedly targeting a bicycle is perfectly possible - I have presented a number of scenarios in which it can happen.

Having a bicycle "clocked" at 66mph is no more "unfeasible" than having a forwards moving car "clocked" at -44mph - and yet we have all seen this shown as part of a real enforcement session on the InsideOut program.

Some of the posters to this forum will have come across the now infamous "Motorcycle case" (Pepipoo) - which is potentially identical to the scenario presented in the Daily Mail with the bicycle - except that the rider of the motor cycle was convicted of speeding.

As far as I can tell your argument appears to be that the 66mph bicycle is "misleading" because it isn't possible via slip on the bicycle. Nowhere in the article is it claimed that it was obtained by slip on the bicycle.

The reading of 22mph from the stationary car did not occur via slip either - as is obvious simply by looking at the photograph. Yet you haven't identified this as "misleading". Why not? Because bikes can't do 66mph?

The article mentions a whole host of failure mechanisms - none of which are easy to illustrate with still photographs. As such the photographs simply illustrate the outcome of a test, not how it was conducted.

I don't think there's any substantial disagreement. I think it's a waste of time to discuss things we all agree about.

But I could be wrong, so please disregard my previous message. Everyone should feel free to discus the matter.

The botttom line is this: the Daily Mail said they 'measured' a push bike at 66mph. They didn't - probably they thought they did. Yes, it's an LTI 2020 practical problem. But it's also a very misleading description of a test.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

What, this one?

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Time to take responsibility for our actions.. and don't be afraid of speaking out!

Oh yes, excellant!!