Accuracy of Speed Measuring Equipment

[hawk20]

I can remember a case like this about 4 yrears ago when a FIAT punto or something like that was clocked at 120+ mph. the driver went to court and the car was road tested at the top gear track. The case was thrown out as the car could not get to that speed. i may have got the car wrong but ...........go figure

It was a Reliant Robin

 

[Dieselman]

The device used in this case was a manual timing device. If the car was traveling at say 120mph timed over 0.5 mile, and the operator made an error of timing of 1 second due to reactions, then the indicated speed would be 127mph.

That doesn't mean they are corrupt or lying, just that the speed the vehicle was being timed at was so fast the operator couldn't react quickly enough.

At 60mph, which is the road limit it would be easier to judge the start point and would give more reaction time, but even if a 1 second error was made it would only add 2mph to the measured speed.

The prosecution only needs to adequately prove the driver was speeding to uphold a conviction. They don't need the exact figure.

 

[Shude]

In extreme cases such as these, maybe the car should be confiscated on the spot to ensure no tinkering can be done to slow down the vehicle in question prior to it being speed tested.

Proving how fast the car can go actually tells us nothing about how fast the car was going at the time of the alleged speeding. Except perhaps that on a track with no corners the speed was definitely not faster than x.

 

[ringway]

A building has been snapped at 30mph before

Those Polish builders do construct at a such a rapid rate.. quite reasonable prices too

 

[recycled]

It was a Reliant Robin

Thanks and here is another one
http://www.dailymail.co.uk/motoring...e--buying-car-proving-manage-speed-85mph.html

That doesn't mean they are corrupt or lying, just that the speed the vehicle was being timed at was so fast the operator couldn't react quickly enough.

I never said for sure they were lying or corrupt, but you do not know for sure that they were not lying or being corrupt from that article either.
What i am saying is that the need/desire for speed enforcement and fine collecting may or may not be clouding common sense and judgement.

Has one of them who was a member of a certain organisation not just being fired after claiming his family registered him in without his knowledge which was proven to be not the case

I am more worried about the devices than its users though

In which other prosecution cases do you have to supply the prosecutor with evidence which he would need to successfully prosecute you while they sit in their office all day and you run around looking for that evidence, buying back your own car e.t.c and then you have to defend yourself as well.

basically murder cases are well investigated, thorough examinations e.t.c to make sure there is no miscarriage of justice, when it comes to cars/ speed enforcement, leaves a lot to be desired but it is a topic that has been done to death so let us just move on.

Someone will soon come along to tell us we do not know the total facts of the case and i will tend to agree with that.

P.s Not having a go at anyone or any profession

 

[Dieselman]

I never said for sure they were lying or corrupt,

Sure..

not if you can prove the officer is misleading the court or has mislead it in the past

but you do not know for sure that they were not lying or being corrupt from that article either.

But as that hasn't been brought into question by anyone but you, it would be reasonable to believe they weren't....

P.s Not having a go at anyone or any profession

Sure, again..

it's one long Merry-Go-Round with you, isn't it Recycled..

which is why I'm out..

 

[recycled]

Sure..


But as that hasn't been brought into question by anyone but you, it would be reasonable to believe they weren't....



Sure, again..

it's one long Merry-Go-Round with you, isn't it Recycled..

which is why I'm out..

Nice editing, should work in the press
The problem with you is that you always cannot make an informed case without always and forever stirring things up .

There we go again the dieselman who knows all the good/ bad and right things that happen in the UK while telling all to those who do not.

As i do not know all the answers i leave it to Dieselman to tell us who the lying and corrupt people are and who those are not because i am sure you cannot tell all from just looking at the newspaper articles.

I certainly cannot
and do not forget the ignore button is always there for my merry- go- rounds

 

[Rovinghawk]

maybe the car should be confiscated on the spot to ensure no tinkering can be done to slow down the vehicle in question prior to it being speed tested.

So, apart from trying to prosecute him for something he didn't do, confiscate an innocent man's car until proven innocent? (nb- innocent of the crime alleged)

Sounds a bit presumptuous to me, not to mention fascist tactics by the authorities. You might want to reconsider the wisom of your idea.

RH

 

[raymont]

My concern with this is if the speed device can be out by so much as to show a speed of 176 against an admitted 105, or even 126 as the max stated top speed of the car, what reason is there to believe a recorded speed of, say, 60 in a 50 limit. The error from 50 to 60 being less than that at the speeds mentioned above.

In another thread a bike was claimed to be doing 122 when, as I posted at the time, it didn’t look like it to me for the reasons I gave.

I’m not defending these riders / drivers, seems they were driving / riding stupidly. But I am questioning the accuracy of the equipment used to measure the speeds.

 

[Dryce]

My concern with this is if the speed device can be out by so much as to show a speed of 176 against an admitted 105, or even 126 as the max stated top speed of the car, what reason is there to believe a recorded speed of, say, 60 in a 50 limit. The error from 50 to 60 being less than that at the speeds mentioned above.

If this is a timing error then the size of the error will be related to the speed.

So, for example, if you are timing a vehicle over 0.5 miles and it's doing 180 then the total time to cover the distance is 10 seconds. An error of 1 second is 18mph. A discrepancy of 1s for vehicle traveling at 120mph is 8mph. And 1s error at 60mph is 2mph.

Basically (and counter intuitively) a large discrepancy implies guilt rather than innocence!

 

[BTB 500]

if you are timing a vehicle over 0.5 miles and it's doing 180 then the total time to cover the distance is 10 seconds. An error of 1 second is 18mph.

[pedant]Well, an average error of 18 mph. 9 seconds would give 200 mph (20 mph error), 11 seconds would give 164 mph (16 mph error).[/pedant]

 

[raymont]

Believe the min distance that can be used is .125 mile.

At more mundane speeds / time to travel .125 mile are:

60mph 7.5secs
64mph 7.0secs
69mph 6.5secs
75mph 6.0secs
78mph 5.75secs
82mph 5.5secs

This means that if you’re doing 70 in a 70 limit and the time is out by less than a second you could be looking at 3points, a fine, maybe loss of licence (totting up) and maybe loss of your job. All because of a human timing error of less than a second.

This is before any error in the distance is included.

Wrt the bike case believe it was a hand held laser device not a time distance calculation.

 

[Sp!ke]

When you are looking at reaction times you have to factor in reactions twice.

Not only that, but you have to factor in the fact that the reactions are opposites. When you start the timer, you are not sure whether to start timing or not (shall I time the white car or the red one...) but when you stop the timer, this action is anticipated so you could actually stop the device too early.

Average reaction time is .7 seconds. Worst case, .7 secs late to start the timer and .7 seconds early when you stop it.

1.4 seconds over a tenth of a mile, there's quite a significant difference

 

[st4]

.

The prosecution only needs to adequately prove the driver was speeding to uphold a conviction. They don't need the exact figure.

And if they CAN'T come up with an accurate figure then how can they prove he was speeding, to labour the point....if I accused you of speeding and then you asked me how fast you were going and I couldn't give you a factual figure (something you are keen on) you'd probably laugh in my face.

To me its simple, to know if someone is speeding and be able to prove it you need a figure. This could be an average between two points or the figure from the laser/radar gun.

170mph+ in an elise does sound tough, did the operator aim the gun at a plane in the air to get that number (plucked it out the sky)....

The driver shouldn't have admitted anything, certainly not anything above 100mph anyway. So whilst he ain't behind bars, he really isn't off lightly (2yr ban etc)-he should have had that one thrown out of court or gone for a plea of 61mph or something

 

[Swiss Toni]

And if they CAN'T come up with an accurate figure then how can they prove he was speeding, to labour the point....if I accused you of speeding and then you asked me how fast you were going and I couldn't give you a factual figure (something you are keen on) you'd probably laugh in my face.

To me its simple, to know if someone is speeding and be able to prove it you need a figure. This could be an average between two points or the figure from the laser/radar gun.

170mph+ in an elise does sound tough, did the operator aim the gun at a plane in the air to get that number (plucked it out the sky)....

The driver shouldn't have admitted anything, certainly not anything above 100mph anyway. So whilst he ain't behind bars, he really isn't off lightly (2yr ban etc)-he should have had that one thrown out of court or gone for a plea of 61mph or something

You should be a solicitor.

 

[st4]

You should be a solicitor.

I am not clever enough and I rant too much-

I find it amazing that road crimes are so easily prosecuted but when you ring the cops and youths are loitering with intent their human rights this and social inclusion that means nothing is done about it, but as soon as someone does something antisocial in a car a conviction is sealed. Why not convict the buckfast swilling louts who were loitering in the office car park today @9am (I am not making this up either) with breach of the peace (down in England its public order offences).

The British tax paying motorist gets a bum deal, thats all.

Rant over for now.

 

[Swiss Toni]

I am not clever enough and I rant too much-

Both are requirements for the job

 

[st4]

Both are requirements for the job

And a degree in law which I couldn't study for. I'll stick to debt recovery, its fun

 

[Dieselman]

170mph+ in an elise does sound tough, did the operator aim the gun at a plane in the air to get that number (plucked it out the sky)....

This was a manual timing device not a 'gun'.

The driver was prosecuted for Dangerous driving, not the speeding offense as such, but to gain a successful prosecution the CPS/police don't have to prove a certain speed was reached, just that the limit was broken.

I'm sure the diver took the speed of 105mph as speed above that could definitely be proven, even if a higher speed couldn't.
Maybe he should've had you as his brief and contested it and let them go for 130mph and a prison sentence..

 

[Swiss Toni]

This was a manual timing device not a 'gun'.

The driver was prosecuted for Dangerous driving, not the speeding offense as such, but to gain a successful prosecution the CPS/police don't have to prove a certain speed was reached, just that the limit was broken.

I'm sure the diver took the speed of 105mph as speed above that could definitely be proven, even if a higher speed couldn't.
Maybe he should've had you as his brief and contested it and let them go for 130mph and a prison sentence..

Did you two go to law school together?

Its nice to be in such a lighthearted forum where micky-taking is taken in the spirit it is intended.