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Van driver uses GPS data to beat speeding fine

Article by: Darren Griffin
Date: 12 Nov 2009

pocketgpsworld.comA van driver clocked by a speed gun travelling at 61mph in a 50mph zone has used GPS data to successfully challenge the prosecution.

Gareth Powell, was driving along the A4174 near Bristol in November 2008 when he was recorded allegedly speeding. Powell was so certain that he was travelling within the limit that he contacted Navman Wireless who operated the vehicle tracking equipment installed in his van.

Tracking records showed that the van had in fact been travelling at 48mph.

Navman Wireless Director Barry Neill attended court as an expert witness and told the court that the GPS fix was excellent at the time of the alleged offence with eight satellites in view.

As a result the case was dismissed by Magistrates on 30th October this year.

Whilst this is excellent news it yet again begs the question, how many other prosecutions are based on false or erroneous evidence as in this case? Is it time that laser speed gun equipment was withdrawn whilst it is re-assessed for accuracy?

Posted by NickG on Thu Nov 12, 2009 9:27 am Reply with quote

I hope the RoadHawk data could also be used for this, but I guess it will probably have been deleted by the time you find out you've got a ticket.

Twitter: @nickg_uk

Posted by Darren on Thu Nov 12, 2009 9:31 am Reply with quote

Yes probably unless you swap cards each week and retain for a period or use a large card. Wonder what the largest card it will us is?

Darren Griffin - Editor

Posted by shelmo on Thu Nov 12, 2009 9:41 am Reply with quote

I currently have an 8GB card in my roadhawk, but I understand that it will take 16GB.

Posted by Darren on Thu Nov 12, 2009 9:44 am Reply with quote

OT for this thread so I'll continue discussion on cards etc in the Roadhawk thread here.

Darren Griffin - Editor

Posted by Darren on Thu Nov 12, 2009 10:47 am Reply with quote

We all need to be very concerned about this. In most circumstances we are forced to accept the evidence from these cameras, laser, GATSO etc as gospel.

Our only recourse is to question their accuracy. In most cases such defences have failed even where there has been expert evidence that calls into question the accuracy.

Anything we can do as motorists to disprove the data is for the better and if we all had equipment such as the Roadhawk with data that can be offered as evidence then we might just see that they are wrong a lot more often than we realise Evil or Very Mad

Darren Griffin - Editor

Posted by GerryC on Thu Nov 12, 2009 11:23 am Reply with quote

With GPS on lots of iPhones and smartphones, I'm now wondering if the accuracy of mobiles, gatsos etc will be brought into more doubt due to the number of devices out there that could, in theory, be capturing this data on behalf of the motorist.

Sorry, but I have to ask: "Is there an app for that?" Out of here

Cameralert for Android
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Posted by antsnest on Fri Nov 13, 2009 10:17 am Reply with quote

The real problem, which the authorities refuse to accept is that the laser speed gun LTI 20-20 is prone to errors, particularly slippage, because it uses a narrow beam illuminating only a small area of the vehicle being measured. Thus if the beam moves up the windscreen or along the bonnet during the measurement large errors can be induced. The car is a moving target, and unless travelling directly towards the laser gun must be tracked by the operator with considerable accuracy if errors are to be avoided. The Gatso is a wide beam device and does not suffer these errors

The Mail had an interesting article on these guns some time ago - recommended reading.


Posted by Darren on Fri Nov 13, 2009 10:36 am Reply with quote

I've split the discussion on blackbox hardware etc to a new thread here as it's OT for this news item.

Please feel free to continue discussion of tech in that thread.

Darren Griffin - Editor

Posted by UKSNAPPER on Fri Nov 13, 2009 11:55 am Reply with quote

As a competition shooter I am under no illusion as to how accurate a laser gun is in the hands of anyone,let alone an exited cop who has just had a cup of caffeine laced coffee.
Holding a sight picture on a still target is difficult, on a moving one is almost impossible.
Thats why shotguns are used to hit moving objects and not rifles.
Handguns are even less accurate and holding aim on a target that is moving both forward and up and down at the same time would stress even an Olympic marksman.

Id rather be riding a Motorcycle but My Subaru Forester SH is pretty good too.

Posted by BrianCollison on Fri Nov 13, 2009 12:30 pm Reply with quote

I did see a documentary about speed cameras a while ago, they talked to the man operating the camera, and he said he had been caught himself.
The camera was in a van and on a stand, so there was no problem in aiming it, you could see what this camera could see and the speed of the vehicles at the time, but it was at his discretion which ones he clicked on.


Posted by UKSNAPPER on Fri Nov 13, 2009 12:41 pm Reply with quote

I don't own a TV so perhaps miss some of the more educational programmes.
I thought the laser guns were hand held jobs.
Note to self,do some research on the web:-))
Thanks for the info

Id rather be riding a Motorcycle but My Subaru Forester SH is pretty good too.

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