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Old February 12th 08, 12:02 PM posted to uk.transport.london
Mizter T Mizter T is offline
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First recorded activity at LondonBanter: May 2005
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Default M25 Speed cameras

On 12 Feb, 12:45, Roland Perry wrote:
In message
, at
04:26:08 on Tue, 12 Feb 2008, Mizter T remarked:

The new digital cameras are going to be set at the normal 10% 0f the speed
limit + 2mph (80mph + and your taking a risk basically)


A true 80mph will typically be over 95mph indicated, so I have no
sympathy for people caught by these cameras.


Perhaps I'm being thick Roland but I don't really understand the point
you're making - how is "a true 80mph" in fact "typically [...] over
95mph indicated" ?!


Sorry, a typo. I meant 85mph, of course.
--
Roland Perry



OK, stupidly I hadn't figured that out!

I've never really used a sat-nav system to compare true speeds with
indicated speeds, so I've never really been aware of the difference
between the 'true' speed I've been travelling at as opposed to the
'indicated' speed.

I guess that implementing a very accurate vehicle speedometer system
is hard to do, so I wonder if most vehicle (and in particular car)
manufacturers design their speedometers "on the safe side", so as to
indicate a faster speed than the true speed - based on the rationale
that it's better for drivers to think they're going faster than they
are, rather than think they are going slower than they are?