Safe Speed Forums

According to a trailer seen tonight on BBC South West, tomorrow's edition of Inside Out is to highlight the fallibility of hand-held speed traps. In the trailer, they showed a stationary wall recorded as travelling at 8 mph!

Should be interesting.

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Will

There's a summary of the program here for those outside the region or who missed it.

Garratt claims that the LTI 20/20 indicates an error condition should slip be present. In the video evidence that showed speeds recorded in the wrong direction (negative values), the status shown on the video was either TIMEOUT or an error condition in all cases, which supports Garratt's claim.

However, there are documented cases (e.g. on Pepipoo) where the scameratsi have attempted to obtain a conviction where the equipment showed these errors. You can find details of one such case at http://pepipoo.com/Case_Files/Case_file_11.htm, which relates Gwent Police's attempt to obtain such a conviction. Note that in this case, the police relied upon Garratt's expert opinion - even though the equipment clearly showed that the speed readings were not safe. Also, the cynic in me wonders why Garratt's company got their solicitors to suppress Garratt's statement if they were completely above board.

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Will

2 MPH....the manufacturers say the accuracy is +/- 1MPH
From the manufacturers spec...

Dimensions: 3.5 in x 5 in x 8 in
Weight: 4.5 lbs
Speed Measurement
Distance: 30 ft to 3500 ft
Speed Maximum: +200 mph to -200 mph (accurate zero reading)
Accuracy: +/- 1 mph
Acquisition Time: 0.3 seconds
Range Measurement
Distance: 30 ft to 3500 ft
Accuracy: +/- 6 inches
Acquisition Time: 0.3 seconds


I think this will be a show stopper if we get graduated fines.

Of course Cumbria used to rely on these 100% did they not. Maybe they got wind of this before they shut the forum down. I seem to remember a VERY long thread on 20/20 reliability...

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Speed camera policy Kills

I'm afraid you don't know what you are talking about.

The LTI 20.20 will display a speed reading or an error - never both concurrently.

TIMEOUT is placed on the screen to prevent the scenario where a speed reading is obtained on one target and then the video camera is moved to another. It ALWAYS appears a few frames after a VALID speed reading has been obtained. TIMEOUT is not an ERROR - it is simple a time out of a valid speed reading.

The error codes E01, E02, E03 are displayed when the device has trapped an error. Quite often you see E03 leading up to a valid speed reading.

A speed reading is displayed on the LTI 20.20, if and only if it thinks that reading is valid.

Mr. Garratt's claim is a false one - obviously. If you can obtain a speed reading from a stationary object, the LTI 20.20 believes it is measuring a moving target. So how can it tell that an object is moving, really moving, or really, really moving.

It was 58mph.

You can get pretty much any speed reading you like. Take a look at these 1/2 Mb MPEG files:

http://www.pepipoo.org/files/Las_lti2020-100mph.mpg
http://www.pepipoo.org/files/Las_stalker-226mph.mpg
http://www.pepipoo.org/files/Las_ultralyte-72mph.mpg