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 Post subject: Enforcement thresholds
PostPosted: Sun Dec 13, 2009 20:48 
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why would it be unusual to get an NIP for 10% +2mph?

The ACPO Speed Enforement Guidelines had a table of the enforcement speeds and just before the table it said:
"The guidance to police officers is that it is anticipated that, other than in the most exceptional circumstances, the issue of fixed penalty notices and summonses is likely to be the minimum appropriate enforcement action as soon as the following speeds have been reached"

The underline is mine.

so you would be getting 100,000's of people informing you that they received their notices for 10% +2mph because that is the level enforcement starts and the level at which most are issued. Well you would if many bothered to read your forum.

You should know that enforcement does not start 1mph above 10% +2mph.




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PostPosted: Sun Dec 13, 2009 20:53 
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GreenShed wrote:
why would it be unusual to get an NIP for 10% +2mph?

The ACPO Speed Enforement Guidelines had a table of the enforcement speeds and just before the table it said:
"The guidance to police officers is that it is anticipated that, other than in the most exceptional circumstances, the issue of fixed penalty notices and summonses is likely to be the minimum appropriate enforcement action as soon as the following speeds have been reached"

The underline is mine.

so you would be getting 100,000's of people informing you that they received their notices for 10% +2mph because that is the level enforcement starts and the level at which most are issued. Well you would if many bothered to read your forum.

You should know that enforcement does not start 1mph above 10% +2mph.

I think you should read the posts within the forums, especially the one immediately before your own :roll: Hint: Jeff Green ... at

It seems like you're typing too fast (faster than you're thinking anyway); where do I send your PFN? :lol:

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PostPosted: Sun Dec 13, 2009 23:19 
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greenshed wrote:
...received their notices for 10% +2mph because that is the level enforcement starts and the level at which most are issued.

My bold above. Is this last statement really true?

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PostPosted: Mon Dec 14, 2009 10:12 
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Steve wrote:
GreenShed wrote:
why would it be unusual to get an NIP for 10% +2mph?

The ACPO Speed Enforement Guidelines had a table of the enforcement speeds and just before the table it said:
"The guidance to police officers is that it is anticipated that, other than in the most exceptional circumstances, the issue of fixed penalty notices and summonses is likely to be the minimum appropriate enforcement action as soon as the following speeds have been reached"

The underline is mine.

so you would be getting 100,000's of people informing you that they received their notices for 10% +2mph because that is the level enforcement starts and the level at which most are issued. Well you would if many bothered to read your forum.

You should know that enforcement does not start 1mph above 10% +2mph.

I think you should read the posts within the forums, especially the one immediately before your own :roll: Hint: Jeff Green ... at

It seems like you're typing too fast (faster than you're thinking anyway); where do I send your PFN? :lol:

Some partnerships operate at the +3mph threshold but do not have to do so that is up to them. Also it appears that Mr. Green is at the Council so is not the best person to know the thresholds operated. I have no idea what thresholds are operated in Wales but have commented upon the ACPO Speed Enforcement Policy as published. There is a common misconception that the threshold is, say 36mph in a 30mph speed limit where it is published as 35mph.
There is every chance Mr. Green has made the same mistake as many others have, equally he may be right for the area in which he works. Either way, 35mph prosecutions are commonplace and the published policy has made it clear what the threshold is an how it operates.


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PostPosted: Mon Dec 14, 2009 10:15 
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malcolmw wrote:
greenshed wrote:
...received their notices for 10% +2mph because that is the level enforcement starts and the level at which most are issued.

My bold above. Is this last statement really true?

Sit back and have a little think.

You have traffic travelling at speeds above the speed limit and it passes some speed enforcement activity; what speed do you reckon would be most common?

The lowest speed that is enforced, perhaps?

That would be the obvious answer I would have thought. This is supported by the results also.


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PostPosted: Mon Dec 14, 2009 10:33 
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GreenShed wrote:
You have traffic travelling at speeds above the speed limit and it passes some speed enforcement activity; what speed do you reckon would be most common?

The lowest speed that is enforced, perhaps?

That would be the obvious answer I would have thought. This is supported by the results also.

Sit back and have a little think.

This shows the partnerships are generally opting for the lowest enforcement threshold available to them.
I can’t think why…

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PostPosted: Mon Dec 14, 2009 10:53 
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Steve wrote:
GreenShed wrote:
You have traffic travelling at speeds above the speed limit and it passes some speed enforcement activity; what speed do you reckon would be most common?

The lowest speed that is enforced, perhaps?

That would be the obvious answer I would have thought. This is supported by the results also.

Sit back and have a little think.

This shows the partnerships are generally opting for the lowest enforcement threshold available to them.
I can’t think why…

You need to get yourself educated beyond simply chanting popular anti-camera sound-bytes, RTTM etc.

See:
A study of crashes within rural 60 km/h zones involving injuries to car occupants found that the relative risk of crash involvement doubles, or more, for each increase of 5 km/h of travelling speed above 60 km/h. Travelling at 5 km/h above a road speed limit of 60 km/h results in an increase in the relative risk of being involved in a casualty crash that is comparable with having a blood alcohol concentration (BAC) of 0.05 gram per decilitre (g/dl)
Image

McLean J, Kloeden C. Alcohol, travelling speed and the risk of crash involvement. In: Mayhew DR, Dussault C, eds. Proceedings of the 16th International
Conference on Alcohol, Drugs and Traffic Safety, Montreal, 4–9 August 2002. Montreal, Société de l’assurance automobile du Québec, 2002:73–79 (http://www.saaq.gouv.qc.ca/t2002/actes/pdf/(07a).pdf)

Is it coincidence that the ACPO speed enforcement thresholds are coincident with the enforcement threshold for blood-alcohol levels as far as collision risk is concerned? This would be one very good reason to use ACPO speed enforcement thresholds. McLean and Kloeden express surprise and frustration in their conclusion that an arrest and immediate ban is awarded for blood-alcohol when excess speed producing the same levels of risk is seen as being too low or enforcement considered Draconian; the paradox is alarming!


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PostPosted: Mon Dec 14, 2009 11:14 
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GreenShed wrote:
You need to get yourself educated beyond simply chanting popular anti-camera sound-bytes, RTTM etc.

That's funny, because that's exactly where you need to get yourself educated :lol:
The confounding factors of RTTM, long-term trends and BOS are all very valid and significant when it comes to discussing effectiveness of speed cameras.
There's no getting around that simple fact, as well as the SCPs not bothering with them, no matter how much you try to divert away from that embarrassing fact.

GreenShed wrote:

Maybe the limits in Australia during the 1995-1996 period (before cameras did their damage) where appropriate? I think it is safe to say the majority of today’s UK drivers feel that not the case on today's roads.

I can foresee a thread split.

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PostPosted: Mon Dec 14, 2009 11:23 
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Steve wrote:
GreenShed wrote:
You need to get yourself educated beyond simply chanting popular anti-camera sound-bytes, RTTM etc.

That's funny, because that's exactly where you need to get yourself educated :lol:
The confounding factors of RTTM, long-term trends and BOS are all very valid and significant when it comes to discussing effectiveness of speed cameras.
There's no getting around that simple fact, as well as the SCPs not bothering with them, no matter how much you try to divert away from that embarrassing fact.

GreenShed wrote:

Maybe the limits in Australia during the 1995-1996 period (before cameras did their damage) where appropriate? I think it is safe to say the majority of today’s UK drivers feel that not the case on today's roads.

I can foresee a thread split.

What evidence of damage by cameras do you have? You have summed this up in a rather inappropriate and offhand way; it does you no service perhaps.

Bring us the benefit of the evidence of widespread worsening of casualty figures by the introduction of speed enforcement measures beyond the unrecognised publication of it in this campaign.


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PostPosted: Mon Dec 14, 2009 13:16 
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GreenShed wrote:
What evidence of damage by cameras do you have? You have summed this up in a rather inappropriate and offhand way; it does you no service perhaps.

No I haven't; I've not even started on that path. All I've done so far is demonstrate the untruths perpetuated by the SCPs (and other confounding factors). Of course that does result in some damage: the perception of priorities on road safety.

To answer your question: there has been a clear (and expected) mathematical trend with 'fatalities vs net distance driven' from 1950 to 2000, with a high level of confidence.
Image
(Plug in the latest numbers and see what you get...)

There has been a marked deviation from that trend from 2000 onwards, yet improvements in all areas of road safety are still ongoing. Apart from one factor, we have no reason to expect, or explain, that deviation from trend – the "fatality gap". That deviation from trend, itself a clear trend, has a rather strong correlation with that one factor, the only one that was introduced/changed at that time: the reliance/activities of the SCPs.
How could this have come about? How about considering the various negative side effects?

GreenShed wrote:
Bring us the benefit of the evidence of widespread worsening of casualty figures by the introduction of speed enforcement measures beyond the unrecognised publication of it in this campaign.

Bring us proof of the benefit of the evidence of widespread bettering of casualty figures by the introduction of speed enforcement measures when accounting for all of RTTM, long-term trends and ‘Bias On Selection’, publicised anywhere; that is the real question that should be asked and has been since the beginning. That onus is not on us.

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 Post subject: Thread split
PostPosted: Mon Dec 14, 2009 19:02 
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Folks, the thread has been split. See the first post in this thread for details.


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PostPosted: Tue Dec 15, 2009 07:05 
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GreenShed wrote:
Bring us the benefit of the evidence of widespread worsening of casualty figures by the introduction of speed enforcement measures beyond the unrecognised publication of it in this campaign.

Be delighted to - but who is 'us' ?

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PostPosted: Tue Dec 15, 2009 12:58 
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SafeSpeedv2 wrote:
GreenShed wrote:
Bring us the benefit of the evidence of widespread worsening of casualty figures by the introduction of speed enforcement measures beyond the unrecognised publication of it in this campaign.

Be delighted to - but who is 'us' ?

It would be the readers here, so not many in the group.


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PostPosted: Thu Dec 24, 2009 13:01 
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Greenshed , you must be dizzy from the rings we are running around you/the SCPs.

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PostPosted: Thu Dec 24, 2009 18:35 
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GreenShed, I take it you are aware that the study you cite has nothing to do with the matter at hand, instead being about the relative dangers of drunk driving. I presume you are also aware that the table you have copied out, misspelling headings whilst doing so, has the footnotes omitted and does not illustrate anything like what you would like us to believe it does.

Deceptive practice at best.

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PostPosted: Sat Dec 26, 2009 12:40 
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RobinXe wrote:
GreenShed, I take it you are aware that the study you cite has nothing to do with the matter at hand, instead being about the relative dangers of drunk driving. I presume you are also aware that the table you have copied out, misspelling headings whilst doing so, has the footnotes omitted and does not illustrate anything like what you would like us to believe it does.

Deceptive practice at best.

Post it all up and explain why your comments detract from the relative risks of alcohol and speed in excess of the limit follow closely up to and shortly after the enforcement thresholds.

The study wasn't about a single issue it was about both issues and the conclusions are clear, the report concluding that it is surprising why the penalties and perceived risks of both are regarded as being greater for alcohol than excess speed. The report also asks the question why that is when the risks are closely aligned.

The study has shown clearly that the speed enforcement threshold and the alcohol enforcement threshold coincide at a similar risk relative factor when compared to travelling at the speed limit or with a 0 blood alcohol level. That is the point I was making.

The thread was born out of a discussion of the acceptability of penalties being issued at the ACPO speed enforcement threshold so why is this illustration not suitable? It shows that public attitudes to an immediate arrest and guaranteed minimum 1 year ban for driving at a relative risk of 3.2 over no alcohol compared to public horror at a £60 and 3 points penalty for driving at an excess speed with a relative risk of 4.2 compared to driving at the lawful speed limit. That is my summary of the study; if you have a more accurate and challenging summary by all means post it but as yet you have challenged my typing skills (NOT spelling) and have made an unsupported rebuttal of my post, as have others.


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PostPosted: Sat Dec 26, 2009 12:45 
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Steve wrote:
Greenshed , you must be dizzy from the rings we are running around you/the SCPs.

ROFL


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PostPosted: Sat Dec 26, 2009 14:48 
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GreenShed wrote:
Steve wrote:
Greenshed , you must be dizzy from the rings we are running around you/the SCPs.

ROFL

<sigh>
I was expecting an attempt at a logical argument to counter my reasoning given to you.

I've shown you the worsening casualty rate from the long-term trend, and highlighted the good correlation between that deviation from the long-term trend and SCP activity.

I also asked you to provide proof that speed cameras have any KSI benefit at all when accounting for the three obvious confounding factors.

What you responded perfectly sums up your own argument. Face it, you have no answer at all.

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PostPosted: Sat Dec 26, 2009 15:13 
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Steve wrote:
GreenShed wrote:
Steve wrote:
Greenshed , you must be dizzy from the rings we are running around you/the SCPs.

ROFL

<sigh>
I was expecting an attempt at a logical argument to counter my reasoning given to you.

I've shown you the worsening casualty rate from the long-term trend, and highlighted the good correlation between that deviation from the long-term trend and SCP activity.

I also asked you to provide proof that speed cameras have any KSI benefit at all when accounting for the three obvious confounding factors.

What you responded perfectly sums up your own argument. Face it, you have no answer at all.

Your reasoning is poor and unsupported by any fact.
Your yellow regression assumption placed on the chart you have supplied is naive and shows, should you be able to understand the mechanisms behind road safety performance, that you would expect the number of deaths to accelerate in reduction as the numbers become lower. It is quite obvious to anyone with a semblance of understanding of performance figures that there would be a diminished return in impr ovement as the numbers reduced, especially when you consider the rise in the volume of traffic that this chart takes into account.
What can be seen in the later part ofthe chart is an exponential decay, this is what I would expect to see from the imposition of a series of measures that cause a road safety imporvement, an exponential decay that has a series of marked steps as improvements are applied. I interpret the chart you have supplied as exactly that.
Image
If no improvements were made to control traffic collisions and casualties in 1997 to the present day then the chart would have reversed and the situation would have been worse.
Even you would be able to see that.


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PostPosted: Sat Dec 26, 2009 17:11 
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GreenShed wrote:
Your reasoning is poor and unsupported by any fact.

Fact: speed cameras have not been proven to be effective when accounting for the three obvious confounding factors (RTTM, long-term trend, bias on selection).
Fact: the well-established casualty trend significantly deviated when SCPs were brought into road safety policies.

GreenShed wrote:
Your yellow regression assumption

It is not an assumption.
The yellow bar is a 'least squares fit' on the curve from 1950 until 1994 with the width of the bar representing 95% confidence intervals.
http://www.safespeed.org.uk/sscw.html


GreenShed wrote:
placed on the chart you have supplied is naive and shows, should you be able to understand the mechanisms behind road safety performance, that you would expect the number of deaths to accelerate in reduction as the numbers become lower.

No, it wouldn't have to anyone able to understand graphs
The Y-axis is logarythmic. Don’t you know it is proper practice to use a log axis when showing exponential curves?
I thought you were an engineer? :roll:

The graph indeed shows "to anyone with a semblance of understanding of performance figures that there is a diminished return in improvement as the numbers reduced, especially when you consider the rise in the volume of traffic that this chart takes into account.".
:roll:

GreenShed wrote:
What can be seen in the later part ofthe chart is an exponential decay,

Wrong again!
The whole curve is exponential. The final part shows a much lower rate of exponential decay.

GreenShed wrote:
this is what I would expect to see from the imposition of a series of measures that cause a road safety imporvement, an exponential decay that has a series of marked steps as improvements are applied.

This exactly what has been demonstrated from 1950 to 2000, then to a lesser extent afterwards.

Next you'll be saying en extrapolation of that curve shows the fatality rate must become negative at some point in the future :lol:

GreenShed wrote:
If no improvements were made to control traffic collisions and casualties in 1997 to the present day then the chart would have reversed and the situation would have been worse.
Even you would be able to see that.

No I don't. I would expect that curve to level if no more improvements were effected (this is so obvious).

The fact is, we were seeing that relatively strong exponential decay until the SCPs showed up, then that curve tended to flatten out (rate of decay substantially reduce) even though all the other safety improvements continued unabated.
There has been a significant deviation from the well-established long-term trend at 2000, and only 1 factor changed during that time: the existence of the SCPs.
Only SCP support staff wouldn't be able to acknowledge that.

See, you really are dizzy :lol:

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