LTI 20/20 thwarted again.

LTI 20/20 thwarted again.

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Mill Wheel

Original Poster:

6,149 posts

165 months

Thursday 28th April 2011
quotequote all
After the Montgomery case in Carlisle, you would have thought that the SCPs and other users would have tightened up on procedures to ensure that the LTI was not misused.

However, a recent case has once more shown that the device is fallible in the wrong hands!

Speeding accusation of 63mph in a 50mph limit

Operator ex traffic BiB, and yet the Chairman of the bench found operator evidence "unconvincing and unreliable", legalese for He was telling porkies?
Hence not guilty verdict!

http://www.thisisbristol.co.uk/news/Biker-cleared-...
this is Bristol said:
'Other convictions could be on shaky ground' says Bristol biker cleared of speeding

Legal battle: Mark Lindsay, from Windmill Hill, Bristol, has fought a speeding fine as the camera [view] was not fixed on his bike.


By daniel evans crime correspondent

A MOTORCYCLIST who successfully contested a speeding charge is telling other drivers and riders that their convictions could be on shaky ground.

Mark Lindsay, from Windmill Hill, was cleared after a day-long trial in Taunton.

The not guilty verdict of the magistrates called into question whether the laser and camera used by enforcement officer Clive Walsh were aligned properly.

On April 22 last year, Mr Lindsay was apparently clocked driving his 800cc Honda VFR at 63mph on the A4 Portway near Shirehampton as he drove to work in Cardiff.

Having already accepted a fine and three penalty points for driving over the 50mph limit the month before, he decided to contest the second allegation, believing he was not driving as fast as he was accused of.

The 58-year-old software engineer, of Cotswold Road, said: "I asked for photographic evidence and was sent a photograph plus a map showing that the location of the camera unit was the same place as the previous offence.

"I knew the speed could not be right because, since the first offence I had been scrupulously careful about staying within 50mph all along the 50 limit on the Portway.

"The photograph I was sent shows a car directly in line with my bike but ahead of me.

"I am in the inside lane and the car is in the outside lane. I decided that the laser must have somehow picked up the car's speed instead of mine.

"I searched the internet and discovered there are a lot of anomalies with the LTi 20-20 laser system used. Subsequently, video evidence shows my bike in the inside lane, with car accelerating away from me, in the outside lane, clearly going considerably faster."

Video and speed measurement expert Tim Farrow told the court in his opinion the laser device and camera were not aligned properly and the laser had clocked the nearby car. He surmised that either camera enforcement officer Mr Walsh accidently clocked the car, or was deliberately aiming for the car, but as the cross hairs on the video recorded were fixed in the motorbike, the fine was sent to Mr Lindsay.

"I think it's ridiculous that I've had to go through this year-long process for something that should have been thrown out long ago," said Mr Lindsay. "As I was found not guilty, my expert witness Tim Farrow and advice on internet suggests the whole session was erroneous and therefore the 20 other people convicted during this session should have their convictions overturned.

"I would advise them to get in contact with Mr Farrow."

Police spokesman Martin Dunscombe said: "The evidence in this case was placed before the magistrates and we respect the verdict the magistrates came to."

On April 1, Safety Camera Partnerships around the country were disbanded after the Government pulled funding for them. As a consequence, fixed speed cameras and red light cameras in the Avon and Somerset police force area were switched off. However, the force still uses mobile units to catch speeding drivers.

Mr Farrow can be contacted on 01726 63755.
It seems that the LTI laser beam was not aligned with the cross hairs on the video!

saaby93

28,986 posts

147 months

Thursday 28th April 2011
quotequote all
There could be more to it than that
If the bike is travelling at 50mph the tyre in contact with the road is at 0mph while the tyre top is going away from the camera at 100mph.
At some point in line with the cross hairs the spokes are travelling at 65mph away from the camera.

robbyd

565 posts

144 months

Thursday 28th April 2011
quotequote all
How can the contact patch be 0 mph while the top be at 100 mph? Would a matt black rubber surface reflect laser beam?

DIW35

4,081 posts

169 months

Thursday 28th April 2011
quotequote all
robbyd said:
How can the contact patch be 0 mph while the top be at 100 mph? Would a matt black rubber surface reflect laser beam?
Because if the contact patch was moving in relation to the ground it was in contact with, the wheel would be in a skid. The centre of the wheel is moving forward at the same velocity as the bike, but the the top of the tyre must be going forward relative to the bike, otherwise it wouldn't be going round.

BertBert

15,385 posts

180 months

Thursday 28th April 2011
quotequote all
It's something called the instantaneous centre of revolution. The contact patch at any given instant is connected to the road which is not moving, so it can't be either! So in that sense the wheel is rotating around the instantaneous centre of revolution.

I think I remember that from A level Maths a couple (eeek) of years ago.

Bert
(well 33 years ago)

Glosphil

3,310 posts

203 months

Thursday 28th April 2011
quotequote all
robbyd said:
How can the contact patch be 0 mph while the top be at 100 mph? Would a matt black rubber surface reflect laser beam?
Relative to the road surface the bottom (contact point) of the tyre is moving in the opposite direction to the motorcycle hence the speed of the tyre must be subtracted from the speed of the m/c resulting in a speed of 0mph. The top of the tyre is moving in the same direction as the m/c and hence the two speeds are added to give 100mph.

Think of it another way. The road is stationary so if the tyre contact point was moving forward at 50mph it would be permanently skidding along the road!

Not so sure that I have explained that very well, but I know what I mean!

robbyd

565 posts

144 months

Thursday 28th April 2011
quotequote all
Does this then rely on the fact that a circle has no beginning or end, surely? I appreciate the angular velocity of the tyre may exceed the velocity of the bike.

EU_Foreigner

2,817 posts

195 months

Thursday 28th April 2011
quotequote all
You try explaining that to an LTI operator, who by the fact that they are only an operator, won't even have done any math to speak off ...

Mill Wheel

Original Poster:

6,149 posts

165 months

Thursday 28th April 2011
quotequote all
I'm sure that your maths and theories have some relevance - but not it seems to this case - although it was decided by magistrates who are not generally known for their technical prowess!

this is Bristol said:
The not guilty verdict of the magistrates called into question whether the laser and camera used by enforcement officer Clive Walsh were aligned properly.
this is Bristol said:
Subsequently, video evidence shows my bike in the inside lane, with car accelerating away from me, in the outside lane, clearly going considerably faster."

Video and speed measurement expert Tim Farrow told the court in his opinion the laser device and camera were not aligned properly and the laser had clocked the nearby car. He surmised that either camera enforcement officer Mr Walsh accidently clocked the car, or was deliberately aiming for the car, but as the cross hairs on the video recorded were fixed on the motorbike, the fine was sent to Mr Lindsay.
It would be nice if we could upload the video, but the court has ruled that the device was not set up correctly - and the police spokesman acceded saying:
Police spokesman Martin Dunscombe said:
"The evidence in this case was placed before the magistrates and we respect the verdict the magistrates came to."
It now remains to be seen whether the other drivers caught in the same session have grounds to appeal their cases. Definitely a need to see the WHOLE video!

Rubber-Ducky

284 posts

174 months

Thursday 28th April 2011
quotequote all
Actually, the contact patch MUST be moving relative to the road in order to provide the required drive. That being the case, the part of the tyre in contact with the road will actually have a negative velocity (be travelling backwards). Additionally, the distance from the axle to the contact patch will be less than the distance from the axle to the top of the tyre thus the top of the tyre will be travelling at slightly more than double the bike's velocity.

Optimum tyre grip occurs at approximately 10% slippage (in the dry) - if tyres didn't slip on the road they simply wouldn't provide any grip. On the plus side, they wouldn't wear out, either!

F i F

39,628 posts

220 months

Thursday 28th April 2011
quotequote all
If the motorcycle is on a conveyor belt would the LTI operator take off?

getmecoat

Seriously though might be an interesting experiment.


Edited by F i F on Thursday 28th April 21:28

14-7

6,233 posts

160 months

Thursday 28th April 2011
quotequote all
WOW!

Another crap thread title that has nothing to do with what actually caused the downfall of the case.

I'd post more but it would be seen as insulting rolleyes towards others banghead.

cptsideways

13,223 posts

221 months

Thursday 28th April 2011
quotequote all
The fact there is another vehicle directly in line of the bike should have sent alarm bells to the person at the Scamership printing off the fines. That alone should have made it inadmissable IMHO.

I guess the video would show the laser was not aligned if you now what to look for.

For those wondering, you dot on the screen is produced by the video equipment - NOT the laser, the laser beam is invisible & must be manually aligned to the vido screen dot by sweeping a fixed target to guess where it is, which itself is not exactly a 100% accurate way of doing it!


14-7

6,233 posts

160 months

Thursday 28th April 2011
quotequote all
cptsideways said:
the laser beam is invisible & must be manually aligned to the vido screen dot by sweeping a fixed target to guess where it is, which itself is not exactly a 100% accurate way of doing it!
Yet this is what most people wouldn't understand in that the sweeping motion would automatically create inaccuracies between the actual LTI view and that of the camera lens as they are totally seperate.

Maybe that is why the OP thinks the LTI has been 'thwarted again'.

All the case has done, and rightly so, is show that the operator has to set the equipment up correctly.

Davidonly

1,080 posts

162 months

Thursday 28th April 2011
quotequote all
DODGY SCOPE smile is back!

saaby93

28,986 posts

147 months

Thursday 28th April 2011
quotequote all
14-7 said:
All the case has done, and rightly so, is show that the operator has to set the equipment up correctly.
I'm not sure it has
Puff has been in here before explaining that it's only an instantaneous speed reading that's taken by the machine which could explain why the cross hair is on the spokes ( or the tyre) and shows 65mph
Anyone with access tried it?

14-7

6,233 posts

160 months

Thursday 28th April 2011
quotequote all
saaby93 said:
which could explain why the cross hair is on the spokes and shows 65mph
Yet the speed reading shows -063mph at 178.7m and you can't see the spokes of the wheel.

Mill Wheel

Original Poster:

6,149 posts

165 months

Friday 29th April 2011
quotequote all
14-7 said:
WOW!

Another crap thread title that has nothing to do with what actually caused the downfall of the case.

I'd post more but it would be seen as insulting rolleyes towards others banghead.
Actually, the thread title IS appropriate.
The LTI is capable of accurately (ETA) measuring the distance of a vehicle, which when coupled to software times the readings, and calculates the speed of the target vehicle.

What has happened in this instance, is that this accuracy has been thwarted by an operator who has allowed the recording device to be used out of alignment with the measuring device... and in the opinion of the magistrates, was not aiming the device correctly either.
Chairman of the Bench said:
...the operators evidence was "unconvincing and unreliable"
A similar occurrence to the Montgomery case, where the actions of the operator were called (successfully) into question.

Now go ahead and be as insulting as you like - I don't mind, I'm used to associating in the company of Puff the tragic and his many alter egos! laugh


Edited by Mill Wheel on Friday 29th April 10:57

streaky

19,311 posts

218 months

Friday 29th April 2011
quotequote all
WRT discussion of the relative speeds of parts of the tyre, I recall that in the days of "radar guns" the owner of a Lotus Elan (IIRC) was acquitted on a speeding charge when he introduced sufficient doubt into the Magistrates' minds that the radar had not been reflected from the tip of one of the 'wings' of the k/o wheel-nuts at the top of its arc. (I.e., he argued successfully that it could have been and demonstrated that it would have been travelling faster than the vehicle. Given that an alleged speed for the vehicle formed part of the prosecution's case, that a calculation showed the vehicle to have been travelling faster than the limit was not considered material.)

Streaky

BrianMillar

192 posts

174 months

Friday 29th April 2011
quotequote all
From the photo the distance from the camera to the bike and the car could be worked out.
Whichever vehicle is 178m away is the one that has been targeted by the laser.
So it should have been easy to prove or disprove if the bike was targeted.