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PostPosted: Thu Jan 14, 2010 22:02 
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Just been catching up on the thread about SPECS3 and went to the http://www.speedcheck.co.uk/specs.htmSpeedCheck site and noticed that in their casualty reduction figures in Northampton, for the A43 the before and after figures
Quote:
* Annual average 36 years prior to installation
** Annual average 61 years post installation
and for the A428
Quote:
* Annual average 50 years prior to installation
** Annual average 50 years post installation


This seems quite an impressive achievement, having SPECS installed for approx 100 years in both cases!


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PostPosted: Thu Jan 14, 2010 22:51 
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:lol:
I'm assuming they meant to have said months instead of years.

That slight error is only the tip of the iceberg.

The obvious factor to consider is Regression to the Mean - the cameras are only installed where a reduction of KSI is expected even without the addition of a camera, but these people are happy for their cameras to wrongly capitalise on that illusion.
This and the separate factor of 'long-term trend' (nationwide KSI reduction expected resulting from global improvements such as: vehicle design, crash response and care) have been proven.

Then there is 'bias on selection' where other independent and genuine safety improvements have been applied (the re-layout of the SPECS enforced M3, J2, southbound for example), but again only the cameras get the credit for any KSI reduction.
Another is their wanton cherry picking of individual best cases, without mention of the typical/average KSI stats for the network as a whole.

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PostPosted: Fri Jan 15, 2010 01:41 
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I know the A428 specs controlled section very well.
It starts at the end of the 30 limit at yardley hastings and ends at the start of the 30 limit at cold brayfield.
Since the installation of the scheme there has been one death in that section that I know of...a motorcyclist who was killed in a collision with a car pulling out of a layby.
Prior to that there were vehicles running into the ditches every week.
A very deceptive road, especially from denton to cold brayfield.

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56 years after it was decided it was needed, the Bedford Bypass is nearing completion. The last single carriageway length of it.We have the most photogenic mayor though, always being photographed doing nothing


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PostPosted: Fri Jan 15, 2010 02:29 
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I have asked them about this - I too think it an error.
I see to that they hint at (daring to) talking about average speed and 85% but they are failing to understand it properly or deliberately.
Speedcheck wrote:
Driver behaviour
Driver behaviour is noticeably better with average speed cameras, with compliance maintained throughout the speed restriction zone. Spot speed cameras often cause 'surfing' or sudden braking at the camera, followed by an increase in speed directly after the camera. This results in a wide distribution of speeds and erratic driver behaviour through the monitored area, promoting flow breakdown and congestion.
In contrast to this, average speed enforcement leads to only small speed variations which creates a smooth flow and safer, more consistent driver behaviour. Compliance is very high, with only a tiny fraction of a percentage of drivers receiving tickets. On a major motorway roadworks scheme, the number of tickets issued weekly is in the hundreds against a typical throughput of over one million vehicles, representing an extremely low violation level.
Traffic volumes change dramatically during any 24 hour period, but average and 85th%ile speeds change very little.
Well I can spend some time pulling this apart !
Of course people comply - who wants some ticket that will after 4 take your license away!
To try to use a forced speed limit area and state that 85% speed vary little - well of course they don't ! It is a totally enforced area with everyone trying to progress at the highest speed allowed, and within judgment ability.
Average camera areas, do cause 'surfing' and the resulting caterpillar after effects too, and this happens every time someone brakes and adjusts their speed by just a few mph, causing many drivers to over and under react, and that adds to the tailgating and near miss incidents within the 'zombie-like' driving styles that happen within these zones.
Speedcheck wrote:
Traffic flow improvements
Traffic flow through a SPECS speed control section improves considerably, resulting in a safer, smoother and more reliable journey. Vehicles can merge and diverge more easily, allowing drivers to enter or leave the carriageway without speeding up or slowing down to find a gap.
The overall result is a conveyor belt type flow, with uniform speeds, little braking, larger headways and fewer collisions. This delivers safer, more reliable journeys for all road users, whilst maximising throughput on roads with a high traffic volume.
They can go on saying this all they like but it is them they are trying to convince the public know that it is not like this. The consistency of bunched and braking traffic creates many difficulties for all those trying to access the Motorway network.
Asking people to drive like robots and remove their responsibility tugs at the very core of good driving abilities. The damage these systems do on drivers and the bad effects that they cause is a sad reflection on how little road safety is being taken by this Government. This sledge hammer to crack a nut shows an appalling lack of attitude and comprehension to this crucially important way to help road safety.

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PostPosted: Fri Jan 15, 2010 09:47 
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But since the system not only slows traffic down, but also provides data on which vehicle was there and at what time, your chance of getting it altered or removed is nil ?

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56 years after it was decided it was needed, the Bedford Bypass is nearing completion. The last single carriageway length of it.We have the most photogenic mayor though, always being photographed doing nothing


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PostPosted: Fri Jan 15, 2010 20:59 
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jomukuk wrote:
But since the system not only slows traffic down, but also provides data on which vehicle was there and at what time, your chance of getting it altered or removed is nil ?



Keep on harping on about it ,but -forget the speed aspect -they've got VRN/time/date /distance travelled -all they now need is to decide on rate/mile and which accounting system to use .Forget Galileo -that's for Europe -the UK 's got SPECs :shock
And it can be slotted in under the guise of road safety .

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PostPosted: Mon Jan 18, 2010 17:01 
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More of the same; wrongly diagnosing the fault and failing to see the cure followed by statistics to make false claims of success.

The case for Speed Cameras reducing KSI goes like this: -

A) It got better, therefore they worked.
B) It didn’t change, therefore they stopped the rot.
C) It became worse, therefore we haven’t used enough.

The equivalent of prescribing aspirin for trench foot until it works...

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