Speed Cameras, are they for safety, or revenue?
Poll: Speed Cameras, are they for safety, or revenue?
Total Members Polled: 478
Discussion
Devil2575 said:
2013BRM said:
It was intended to be anecdotal hence my introduction to the post 'all I can say is what I see', you demand evidence but the posts offering evidence are contested and rebuffed with contrary evidence which is either ignored or countered with yet more evidence. All anyone can do, therefor, is offer experience and experience is what we humans use, ultimately to guide us. At least Vonhosen didn't simply deny my experience as he usually does. Your stats can be and are contested because you choose them , as the human condition dictates, to support your global view on the subject. Despite me being a long serving member of this website I try my best to be objective. Admittedly this was not always the case. Your claim that our roads are the safest is based on KSIs but that means more survive a crash not that there are fewer crashes, and if my post is incredibly ironic yours is incredibly arrogant to simply dismiss ones experience, but then, it doesn't fit with your point of view does it
So are you saying that you don't agree with UK and global KSI stats?Edited by 2013BRM on Sunday 25th January 14:47
KSI means more survive and less are seriously injured. Insurance claims are falling according to the insurance industry.
http://www.insuranceage.co.uk/insurance-age/news/2...
Do you contest the insurance industry stats too?
This is the basis for my argument. Our roads are getting safer - less people are killed and less are injured and less people are crashing.
Your evidence is personal experience which if anything can only be used as the basis for a hypothesis; a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.
Given that less people are killed and seriously injured and less accidents are happening you need to come up with something better than personal experiences to support your case.
No where in credible research is personal experience used to provide data.
2013BRM said:
Devil2575 said:
2013BRM said:
It was intended to be anecdotal hence my introduction to the post 'all I can say is what I see', you demand evidence but the posts offering evidence are contested and rebuffed with contrary evidence which is either ignored or countered with yet more evidence. All anyone can do, therefor, is offer experience and experience is what we humans use, ultimately to guide us. At least Vonhosen didn't simply deny my experience as he usually does. Your stats can be and are contested because you choose them , as the human condition dictates, to support your global view on the subject. Despite me being a long serving member of this website I try my best to be objective. Admittedly this was not always the case. Your claim that our roads are the safest is based on KSIs but that means more survive a crash not that there are fewer crashes, and if my post is incredibly ironic yours is incredibly arrogant to simply dismiss ones experience, but then, it doesn't fit with your point of view does it
So are you saying that you don't agree with UK and global KSI stats?Edited by 2013BRM on Sunday 25th January 14:47
KSI means more survive and less are seriously injured. Insurance claims are falling according to the insurance industry.
http://www.insuranceage.co.uk/insurance-age/news/2...
Do you contest the insurance industry stats too?
This is the basis for my argument. Our roads are getting safer - less people are killed and less are injured and less people are crashing.
Your evidence is personal experience which if anything can only be used as the basis for a hypothesis; a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.
Given that less people are killed and seriously injured and less accidents are happening you need to come up with something better than personal experiences to support your case.
No where in credible research is personal experience used to provide data.
turbobloke said:
TfL dismisses criticism of speed camera policy preferring spin to sound analysis
Transport for London has rejected claims that its speed camera investment programme is based on a flawed understanding of the evidence about their effectiveness in reducing casualties. TfL reported last November that speed cameras helped prevent 500 deaths or serious injuries on London’s roads each year, based on data showing that KSIs had fallen by 58% where cameras were installed (LTT 14 Nov 14). The figures, however, ignore the influence of factors such as regression to the mean and trend.
Idris Francis, an engineer who has spent much of his retirement examining speed camera casualty data, wrote to Leon Daniels, TfL’s managing director of surface transport, challenging the claim. The Sunday Telegraph, covered Francis’s criticisms last month (LTT 09 Jan).
Daniels, however, has rejected the criticisms, telling Francis in a letter: “The effectiveness of safety cameras in reducing casualties at the locations where they are implemented is well established. Our position is supported by a number of studies, including the detailed four-year evaluation of the National Safety Camera Programme, produced for the DfT by University College London and Dr Mountain of Liverpool University in 2005. Importantly, this study shows that safety cameras are effective in reducing casualties, even after trend effects and regression towards the mean are taken into account.”
In a response to Daniels, Francis presents a graph, plotting the decline in reported fatal and serious injuries across London and at camera sites. “As you can see there has been no meaningful difference between the rate at which KSI fell at your [camera] sites and the rate at which they fell elsewhere,” he says. “What is more, your senior officials have been fully aware of that at least since September, yet did nothing to block your ludicrous plan to spend tens of millions of more pounds of taxpayers’ money to achieve nothing at all.”
Based on LTT coverage, with my emphasis.
No response to this I see Transport for London has rejected claims that its speed camera investment programme is based on a flawed understanding of the evidence about their effectiveness in reducing casualties. TfL reported last November that speed cameras helped prevent 500 deaths or serious injuries on London’s roads each year, based on data showing that KSIs had fallen by 58% where cameras were installed (LTT 14 Nov 14). The figures, however, ignore the influence of factors such as regression to the mean and trend.
Idris Francis, an engineer who has spent much of his retirement examining speed camera casualty data, wrote to Leon Daniels, TfL’s managing director of surface transport, challenging the claim. The Sunday Telegraph, covered Francis’s criticisms last month (LTT 09 Jan).
Daniels, however, has rejected the criticisms, telling Francis in a letter: “The effectiveness of safety cameras in reducing casualties at the locations where they are implemented is well established. Our position is supported by a number of studies, including the detailed four-year evaluation of the National Safety Camera Programme, produced for the DfT by University College London and Dr Mountain of Liverpool University in 2005. Importantly, this study shows that safety cameras are effective in reducing casualties, even after trend effects and regression towards the mean are taken into account.”
In a response to Daniels, Francis presents a graph, plotting the decline in reported fatal and serious injuries across London and at camera sites. “As you can see there has been no meaningful difference between the rate at which KSI fell at your [camera] sites and the rate at which they fell elsewhere,” he says. “What is more, your senior officials have been fully aware of that at least since September, yet did nothing to block your ludicrous plan to spend tens of millions of more pounds of taxpayers’ money to achieve nothing at all.”
Based on LTT coverage, with my emphasis.
Seeming the point cropped up again last night, yet nobody answered this yesterday...
allergictocheese said:
Here's an interesting philosophical question for a Sunday morning;
If it could be proven that speed cameras had increased the overall number of collisions on our roads, yet due to the lower speeds involved, had actually reduced total KSIs, would this be acceptable, and why?
If it could be proven that speed cameras had increased the overall number of collisions on our roads, yet due to the lower speeds involved, had actually reduced total KSIs, would this be acceptable, and why?
allergictocheese said:
Seeming the point cropped up again last night, yet nobody answered this yesterday...
Could be nobody thinks it actually is interesting, I don't.allergictocheese said:
Here's an interesting philosophical question for a Sunday morning;
If it could be proven that speed cameras had increased the overall number of collisions on our roads, yet due to the lower speeds involved, had actually reduced total KSIs, would this be acceptable, and why?
If it could be proven that speed cameras had increased the overall number of collisions on our roads, yet due to the lower speeds involved, had actually reduced total KSIs, would this be acceptable, and why?
emmaT2014 said:
2013BRM said:
Devil2575 said:
2013BRM said:
It was intended to be anecdotal hence my introduction to the post 'all I can say is what I see', you demand evidence but the posts offering evidence are contested and rebuffed with contrary evidence which is either ignored or countered with yet more evidence. All anyone can do, therefor, is offer experience and experience is what we humans use, ultimately to guide us. At least Vonhosen didn't simply deny my experience as he usually does. Your stats can be and are contested because you choose them , as the human condition dictates, to support your global view on the subject. Despite me being a long serving member of this website I try my best to be objective. Admittedly this was not always the case. Your claim that our roads are the safest is based on KSIs but that means more survive a crash not that there are fewer crashes, and if my post is incredibly ironic yours is incredibly arrogant to simply dismiss ones experience, but then, it doesn't fit with your point of view does it
So are you saying that you don't agree with UK and global KSI stats?Edited by 2013BRM on Sunday 25th January 14:47
KSI means more survive and less are seriously injured. Insurance claims are falling according to the insurance industry.
http://www.insuranceage.co.uk/insurance-age/news/2...
Do you contest the insurance industry stats too?
This is the basis for my argument. Our roads are getting safer - less people are killed and less are injured and less people are crashing.
Your evidence is personal experience which if anything can only be used as the basis for a hypothesis; a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.
Given that less people are killed and seriously injured and less accidents are happening you need to come up with something better than personal experiences to support your case.
No where in credible research is personal experience used to provide data.
His problem is that he can't counter my argument with evidence because he doesn't have any as his opinion is based purely on personal experience.
BTW, I am not paid to do this in any way shape or form.
Edited by Devil2575 on Monday 26th January 11:13
2013BRM said:
Once again, I started my post by saying this was what I see, you ignored that, I also said that KSI's did not represent the amount of accidents, I am intriqued as to what motivates such dogged belief
I explained clearly why what you see isn't evidence. This isn't ignoring stuff befcause it suits, this is based on sound scientific priciples. Go and talk to anyone who works in research and ask them if they use personal experiences as evidence to support an argument.You said that KSIs did not represent the ammount of accidents. You didn't back it up with evidence though. I produced a link to an article by the insurance industry stating that the number of accidents was falling.
2013BRM said:
turbobloke said:
TfL dismisses criticism of speed camera policy preferring spin to sound analysis
Transport for London has rejected claims that its speed camera investment programme is based on a flawed understanding of the evidence about their effectiveness in reducing casualties. TfL reported last November that speed cameras helped prevent 500 deaths or serious injuries on London’s roads each year, based on data showing that KSIs had fallen by 58% where cameras were installed (LTT 14 Nov 14). The figures, however, ignore the influence of factors such as regression to the mean and trend.
Idris Francis, an engineer who has spent much of his retirement examining speed camera casualty data, wrote to Leon Daniels, TfL’s managing director of surface transport, challenging the claim. The Sunday Telegraph, covered Francis’s criticisms last month (LTT 09 Jan).
Daniels, however, has rejected the criticisms, telling Francis in a letter: “The effectiveness of safety cameras in reducing casualties at the locations where they are implemented is well established. Our position is supported by a number of studies, including the detailed four-year evaluation of the National Safety Camera Programme, produced for the DfT by University College London and Dr Mountain of Liverpool University in 2005. Importantly, this study shows that safety cameras are effective in reducing casualties, even after trend effects and regression towards the mean are taken into account.”
In a response to Daniels, Francis presents a graph, plotting the decline in reported fatal and serious injuries across London and at camera sites. “As you can see there has been no meaningful difference between the rate at which KSI fell at your [camera] sites and the rate at which they fell elsewhere,” he says. “What is more, your senior officials have been fully aware of that at least since September, yet did nothing to block your ludicrous plan to spend tens of millions of more pounds of taxpayers’ money to achieve nothing at all.”
Based on LTT coverage, with my emphasis.
No response to this I see Transport for London has rejected claims that its speed camera investment programme is based on a flawed understanding of the evidence about their effectiveness in reducing casualties. TfL reported last November that speed cameras helped prevent 500 deaths or serious injuries on London’s roads each year, based on data showing that KSIs had fallen by 58% where cameras were installed (LTT 14 Nov 14). The figures, however, ignore the influence of factors such as regression to the mean and trend.
Idris Francis, an engineer who has spent much of his retirement examining speed camera casualty data, wrote to Leon Daniels, TfL’s managing director of surface transport, challenging the claim. The Sunday Telegraph, covered Francis’s criticisms last month (LTT 09 Jan).
Daniels, however, has rejected the criticisms, telling Francis in a letter: “The effectiveness of safety cameras in reducing casualties at the locations where they are implemented is well established. Our position is supported by a number of studies, including the detailed four-year evaluation of the National Safety Camera Programme, produced for the DfT by University College London and Dr Mountain of Liverpool University in 2005. Importantly, this study shows that safety cameras are effective in reducing casualties, even after trend effects and regression towards the mean are taken into account.”
In a response to Daniels, Francis presents a graph, plotting the decline in reported fatal and serious injuries across London and at camera sites. “As you can see there has been no meaningful difference between the rate at which KSI fell at your [camera] sites and the rate at which they fell elsewhere,” he says. “What is more, your senior officials have been fully aware of that at least since September, yet did nothing to block your ludicrous plan to spend tens of millions of more pounds of taxpayers’ money to achieve nothing at all.”
Based on LTT coverage, with my emphasis.
Edited by Devil2575 on Monday 26th January 10:26
RobinOakapple said:
Could be nobody thinks it actually is interesting, I don't.
Maybe, though more likely that the answer is difficult to formulate.It's possible (though I think unlikely) the roads are less safe and that accidents are more common than before the proliferation of speed cameras, whilst at the same time, due to speed cameras, average speeds have dropped, resulting in few deaths and serious injuries from those accidents.
In other words, claiming that speed cameras reduce KSIs and at the same time that they increase accidents are not logically bound to be mutually exclusive positions.
allergictocheese said:
Maybe, though more likely that the answer is difficult to formulate.
It's possible (though I think unlikely) the roads are less safe and that accidents are more common than before the proliferation of speed cameras, whilst at the same time, due to speed cameras, average speeds have dropped, resulting in few deaths and serious injuries from those accidents.
In other words, claiming that speed cameras reduce KSIs and at the same time that they increase accidents are not logically bound to be mutually exclusive positions.
Well I reckon if anyone was claiming that they would be glad to hear you think it's ok. It's possible (though I think unlikely) the roads are less safe and that accidents are more common than before the proliferation of speed cameras, whilst at the same time, due to speed cameras, average speeds have dropped, resulting in few deaths and serious injuries from those accidents.
In other words, claiming that speed cameras reduce KSIs and at the same time that they increase accidents are not logically bound to be mutually exclusive positions.
I'd have to say that I'd prefer not to be a KSI than be involved in an accident where nobody got badly hurt. But I don't think driving has got any worse than it always has been.
I'd imagine the only realistic barometer of accident statistics per vehicle/ driver would be figures held by the insurance industry (what I imagine will be a sizeable chunk of RTAs won't be recorded by the Police).
I've been driving since the mid 90s, for a good chunk of that at circa 1000- 1500 miles a week. My anecdotal impression is that the standards of driving are broadly similar to how they've always been, but the roads are significantly busier and the speeds on non-motorway routes slower.
I've been driving since the mid 90s, for a good chunk of that at circa 1000- 1500 miles a week. My anecdotal impression is that the standards of driving are broadly similar to how they've always been, but the roads are significantly busier and the speeds on non-motorway routes slower.
Deadly Dog said:
However, the most glaring fault of all is the apparent lack of real-world control data for performance comparison - an utterly unforgivable omission.
Yes, and just as bad are those reports which use unrepresentative control data.This one, for example, uses data from actual crashes, but, for the control group, uses vehicles which were travelling on the same stretch of road, at the same time of day, and in similar weather and other conditions as the crash-involved vehicles.
However, what is completely absent from the control group are the factors which led to the crashes - eg another vehicle turning directly across the path of the case vehicle - the fundamental factors without which the crashes would not have happened, regardless of the other factors.
They might as well have used Santa's reindeer as the control group.
This misuse of statistical analysis has, even ignoring the numerous other flaws in the report, renders their findings completely invalid.
The problem is, this particular report has been highly influential, and is one of the most widely-cited papers on the subject.
Edited by Phatboy317 on Monday 26th January 13:20
Phatboy317 said:
Deadly Dog said:
However, the most glaring fault of all is the apparent lack of real-world control data for performance comparison - an utterly unforgivable omission.
Yes, and just as bad are those reports which use unrepresentative control data.This one, for example, uses data from actual crashes, but, for the control group, uses vehicles which were travelling on the same stretch of road, at the same time of day, and in similar weather and other conditions as the crash-involved vehicles.
However, what is completely absent from the control group are the factors which led to the crashes - eg another vehicle turning directly across the path of the case vehicle - the fundamental factors without which the crashes would not have happened, regardless of the other factors.
They might as well have used Santa's reindeer as the control group.
This misuse of statistical analysis has, even ignoring the numerous other flaws in the report, renders their findings completely invalid.
The problem is, this particular report has been highly influential, and is one of the most widely-cited papers on the subject.
Edited by Phatboy317 on Monday 26th January 13:20
The selection of the control group seems perfectly valid to me.
The control group has been selected specifically so that it can be compared to the vehicles involved in crashes. It would be no good having a control group on a different road with a different layout or different weather conditions or using buses for example.
The other factors that affected the crash are irrelevant. All crashes will have different factors involved but that's not what they are trying to determine. What they are comparing, at least in part of the study, is the free travelling speed of vehicles not involved in a crash to the free travelling speed of vehicles involved in a crash.
So for example of cars of a similar typre in similar conditions travelling on that road less than 1% were exceeding 80km/hr. However of those that crashed 14% were exceeding 80 km/hr.
What control group would you have liked?
They weren't comparing a before and after scenario where the control shows what happens when no change is made, they were measuring car speeds on a road and comparing them to the speed of cars that crashed on the same road.
Whether or not a vehicle turned into the path of a car causing the crash is of no consequence.
Devil2575 said:
Phatboy317 said:
Deadly Dog said:
However, the most glaring fault of all is the apparent lack of real-world control data for performance comparison - an utterly unforgivable omission.
Yes, and just as bad are those reports which use unrepresentative control data.This one, for example, uses data from actual crashes, but, for the control group, uses vehicles which were travelling on the same stretch of road, at the same time of day, and in similar weather and other conditions as the crash-involved vehicles.
However, what is completely absent from the control group are the factors which led to the crashes - eg another vehicle turning directly across the path of the case vehicle - the fundamental factors without which the crashes would not have happened, regardless of the other factors.
They might as well have used Santa's reindeer as the control group.
This misuse of statistical analysis has, even ignoring the numerous other flaws in the report, renders their findings completely invalid.
The problem is, this particular report has been highly influential, and is one of the most widely-cited papers on the subject.
Edited by Phatboy317 on Monday 26th January 13:20
The selection of the control group seems perfectly valid to me.
The control group has been selected specifically so that it can be compared to the vehicles involved in crashes. It would be no good having a control group on a different road with a different layout or different weather conditions or using buses for example.
The other factors that affected the crash are irrelevant. All crashes will have different factors involved but that's not what they are trying to determine. What they are comparing, at least in part of the study, is the free travelling speed of vehicles not involved in a crash to the free travelling speed of vehicles involved in a crash.
So for example of cars of a similar typre in similar conditions travelling on that road less than 1% were exceeding 80km/hr. However of those that crashed 14% were exceeding 80 km/hr.
What control group would you have liked?
They weren't comparing a before and after scenario where the control shows what happens when no change is made, they were measuring car speeds on a road and comparing them to the speed of cars that crashed on the same road.
Whether or not a vehicle turned into the path of a car causing the crash is of no consequence.
But whereas the probability for vehicles in the control group was extremely small - almost literally a once in a lifetime chance - that of the crash-involved vehicles was already 100%, by virtue of the fact that they had crashed.
It would have been better to have compared the number of crash-involved vehicles in each speed group with the total number of vehicles in the same speed group over the entire period in which all of the crashes occurred.
But the small sample size of the crash-involved vehicles, compared with the total number of vehicle movements in the area over the same period, means that the speeds involved are very much in random noise territory.
And the fact that a speed limit exists would have resulted in a large proportion of the control group being within the limit.
Besides, if they're only interested in the vehicle speeds involved, why did they only include those with a free travelling speed? Surely a speed is a speed, whether constrained or not, or whether constrained by traffic or the speed limit?
And why include only the cases for which an ambulance was required, when the title of the paper only mentions speed and not injuries?
Edited by Phatboy317 on Monday 26th January 20:38
Phatboy317 said:
That's only really true if the prior probability of crashes occurring is the same or similar for both groups.
But whereas the probability for vehicles in the control group was extremely small - almost literally a once in a lifetime chance - that of the crash-involved vehicles was already 100%, by virtue of the fact that they had crashed.
It would have been better to have compared the number of crash-involved vehicles in each speed group with the total number of vehicles in the same speed group over the entire period in which all of the crashes occurred.
But the small sample size of the crash-involved vehicles, compared with the total number of vehicle movements in the area over the same period, means that the speeds involved are very much in random noise territory.
And the fact that a speed limit exists would have resulted in a large proportion of the control group being within the limit.
Besides, if they're only interested in the vehicle speeds involved, why did they only include those with a free travelling speed? Surely a speed is a speed, whether constrained or not, or whether constrained by traffic or the speed limit?
And why include only the cases for which an ambulance was required, when the title of the paper only mentions speed and not injuries?
The point was to compare the free travelling speed distribution of vehicles that crashed with those that didn't. Of course one group had a 100% probability of crashing.But whereas the probability for vehicles in the control group was extremely small - almost literally a once in a lifetime chance - that of the crash-involved vehicles was already 100%, by virtue of the fact that they had crashed.
It would have been better to have compared the number of crash-involved vehicles in each speed group with the total number of vehicles in the same speed group over the entire period in which all of the crashes occurred.
But the small sample size of the crash-involved vehicles, compared with the total number of vehicle movements in the area over the same period, means that the speeds involved are very much in random noise territory.
And the fact that a speed limit exists would have resulted in a large proportion of the control group being within the limit.
Besides, if they're only interested in the vehicle speeds involved, why did they only include those with a free travelling speed? Surely a speed is a speed, whether constrained or not, or whether constrained by traffic or the speed limit?
And why include only the cases for which an ambulance was required, when the title of the paper only mentions speed and not injuries?
Edited by Phatboy317 on Monday 26th January 20:38
They explain clearly why they did what they did. I would always like a larger sample size but that doesn't mean the difference between the two data sets can be accounted for by noise.
Perhaps the reason it's been cited so many times tells you something.
Devil2575 said:
The point was to compare the free travelling speed distribution of vehicles that crashed with those that didn't. Of course one group had a 100% probability of crashing.
They explain clearly why they did what they did. I would always like a larger sample size but that doesn't mean the difference between the two data sets can be accounted for by noise.
Perhaps the reason it's been cited so many times tells you something.
Except that they themselves seem to have some difficulty in identifying a plausible mechanism to explain the rather extreme slope of the speed/risk graph in their findings - read section 5.1.1They explain clearly why they did what they did. I would always like a larger sample size but that doesn't mean the difference between the two data sets can be accounted for by noise.
Perhaps the reason it's been cited so many times tells you something.
There they suggest that the discrepancy between their results and their own physical model may be because of the fact that human behaviour is not always random, and that people are more likely to appear in a vehicle’s path at a range of 50-60m than at 0-10m or 10-20m.
However, this is not supported by their own data. If that were the case then the distribution of distance covered before the collision, calculated from the case data, would be independent of speed, but it's not.
And there are many other sources of bias due to human behaviour, as they acknowledge themselves, one of which I can think of is that failure to slow down for a dangerous junction might simply be a symptom of the same lack of due care and attention which leads to the crash.
So what do we do? How can we be sure that we're accurately gauging the relationship between speed and accidents, without biases getting in the way?
One way is to conduct your own controlled experiments, and the only really practical way of doing this is by way of computer simulations, which are not difficult to create for anyone with programming skills.
One could, for example, simulate a vehicle, or vehicles, travelling along a mile or two of road, with objects appearing in the road at random times and points along the road, and recording a collision if there's a vehicle within its stopping distance of the object at the time it appears - and then perhaps even calculate and record the collision speed.
As long as you keep things, such as the frequency of hazards appearing, within realistic limits, and no biases are introduced by, for example, having the vehicles spaced apart by less than their stopping distances, or having the hazards appearing within a few metres of the start (real life doesn't have starting points) the results should be reasonable.
One could even run two or more simulations in parallel, with the same random conditions, to judge the effect of changing just one parameter while leaving all else unchanged.
I can almost guarantee that doing this will at least give you a fresh look at the issue.
Edited by Phatboy317 on Tuesday 27th January 07:59
woof said:
It's difficult to find actual current figures of how many motorist are being fined for speeding in recent years but in 2007 it was 1.9 million (in 1997 it was just 700,000) and from the current increase in new digital speed cameras tickets being issued in this "new war on motorists" I expect to see that figure be close to 4 million and raising something in the region of £500,000,000 in revenue.
I think your estimate for number and revenue is wildly out if this from 2013 is accurate (1/2 million motorists and £30m in fines)Gassing Station | Speed, Plod & the Law | Top of Page | What's New | My Stuff