Average Speed Cameras for London

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davidg

Well-Known Member
Location
London
These things usually calculate the mean by timing the difference between start and end cameras and assuming an average speed is maintained over the distance rather than measuring speeds at several spots.

yeah, but is it a mean, medium or mode...!
 

vikingcyclist

New Member
Location
Bedford
yeah, but is it a mean, medium or mode...!

Mean, as I said.

The time to travel from the first to the last camera is used to calculate the mean speed across the distance.

Since a limited number of cameras are used there wouldn't be enough sampling to calculate a mode or median.
 
OP
OP
StuartG

StuartG

slower but further
Location
SE London
Yes - thanks for making us think about what they will be recording.

These cameras are currently mostly used on motorways or on similar main roads. Unless it is congested the driver is likely to be maintaining a reasonably constant speed between cameras uninterrupted by junctions, lights, people crossing and cyclists adopting primary ...

Hence in most cases the mean recorded speed is likely to be approaching the maximum speed. Its a jolly good indicator of true driver speeds (except for the Jeremy Clarksons who pull over on to the hard shoulder for a noggin and then crack 150 mph without breaking the average).

Now consider their use in an urban residential environment. Drivers will be constantly varying their speed in reaction to the changing road layouts and be stopped quite frequently and not just for a noggin. The mean speed prosecution has to be set above the limit (say 22 mph in a 20 mph area) - but the likelihood of a driver who hits 35 mph on a straight stretch coming in with an average well below the mean limit is quite high. Would seem to be an Achilles heel for the system. I would have thought hidden random GATSOs might catch more of the speeders than Average Cameras.
 

Origamist

Legendary Member
I should read my response again Stuart.

You might also want to read through this thread - http://www.pistonhea...75&mid=0&nmt=RE: TfL Edges Toward Borough-Wide Average Speed Camera

In any event I can't see this project happening with the current funding issues.:becool:


I can, it's an easy way to fleece money from the poor, downtrodden and perennially persecuted motorist and swell the Treasury's coffers at the same time. Win/win!
 

davidg

Well-Known Member
Location
London
the mean speed or the mean of the speeds is what I would say....

they could use the mode of speeds or median of speed...


just saying
 
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