Speed cameras: Are we interested in evidence?
Discussion
Here's a short video examining the evidence at mobile speed camera sites in Thames Valley (Oxfordshire, Buckinghamshire and Berkshire).
https://www.youtube.com/watch?v=-GqOm-keyss
But are we actually interested in evidence, or do we want policy to be based on our opinions?
https://www.youtube.com/watch?v=-GqOm-keyss
But are we actually interested in evidence, or do we want policy to be based on our opinions?
Zetec-S said:
Where does this data come from?
Excellent question.It's the official database of collisions sent to me by "Thames Valley Safer Roads Partnership" (the speed camera operators).
There's more info under "Supplementary information" at the end of this page:
https://speedcamerareport.co.uk/08_mobile_refs/
Video: https://www.youtube.com/watch?v=-GqOm-keyss
Stick Legs said:
Thank you for going to the effort.
You're welcome.As an engineer, I've always thought that we should seek the best quality evidence.
And if the authorities refuse to provide it, we need to do the work ourselves ...
https://www.youtube.com/watch?v=-GqOm-keyss
768 said:
I guess the answer to the thread title is no.
And there's the problem.Speed cameras were NOT run within scientific trials,
and they have never provided proper evidence of the effect of their speed cameras.
And how have they got away with it?
Because people are not interested in evidence.
This needs to change.
If we are ever to reduce deaths and serious injuries, we must DEMAND proper evidence.
And that needs to be scientific trials for all road safety interventions.
https://www.youtube.com/watch?v=-GqOm-keyss
Greendubber said:
Dave Finney said:
Greendubber said:
I've seen first hand plenty of people killed by excess speed thanks very much.
So that must be due to your line of work. Are you a Police officer involved in collision investigations?The evidence suggests, though, that speed cameras are causing even more fatalities that you then have to attend.
I explain here: "Are speed cameras doing more harm than good? Examining the evidence."
https://www.youtube.com/watch?v=-GqOm-keyss
vonhosen said:
If the allegation is that an unintended consequence of the visible camera themselves, is an adverse effect on driver behaviour/safety ...
It's not an "allegation", it's evidence.And the evidence suggests that speed cameras are causing an increase in death and serious injuries.
Have you seen the video, or read the report?
Griffith4ever said:
Only issue I have with that video is he puts the blame on the post camera increase down to the camera presence when he puts the previous increases ( the factored ones) down to natural spikes in mean numbers. Or did I misunderstand?
Wow, 6 pages of discussion and finally the 1st question about the actual evidence, THANK YOU.The video at 5 minutes could only skim the surface, the detail is on my website.
You've almost got it.
The video examines 2 major factors that influence collision rates:
1) site selection.
2) the speed cameras.
It's the timing that's important.
Site selection influences collision rates:
1) BEFORE the cameras
2) ONLY during the SSP.
Knowing that, we can then remove the effect of site selection so that what is left is the effect of the speed cameras.
So the "previous increases" are not just "down to natural spikes in mean numbers",
they are down to "selection" of sites when collisions were "unusually high".
And this obviously only occurred during the SSP.
Either side of the SSP, collisions occurred at around their "mean" (or normal) rate.
After speed cameras, there was an increase in the "mean" (or normal) rate of fatal and serious collisions.
https://www.youtube.com/watch?v=-GqOm-keyss
heebeegeetee said:
What's causing the increase in collisions at the sites - indeed, do you mean at the actual speed camera sites, or somewhere nearto?
I'm puzzled by the whole thing - I can't see how a camera can cause someone to crash. Equally, I know some locations of popular camera van locations, as clearly do many other locals, and we all slow down and drive calmly as we approach. I guess this can cause problems when those not in the know approach at well over the speed limit and come into 'conflict' with law abiding traffic in front, but I don't see that as a reason to not enforce speed limits.
Yes, these are the "speed camera sites" as defined by the speed camera partnership, ie the stretch of road where the camera operates.I'm puzzled by the whole thing - I can't see how a camera can cause someone to crash. Equally, I know some locations of popular camera van locations, as clearly do many other locals, and we all slow down and drive calmly as we approach. I guess this can cause problems when those not in the know approach at well over the speed limit and come into 'conflict' with law abiding traffic in front, but I don't see that as a reason to not enforce speed limits.
Speed cameras can definitely lead to a collision, just as they can also prevent one.
https://speedcamerareport.co.uk/effects-of-speed-c...
The question is: do they lead to more than they avoid?
The evidence suggests that speed cameras lead to more fatal and serious collisions, than they prevent.
Video: https://www.youtube.com/watch?v=-GqOm-keyss
DaiB said:
I don't understand the statement that accident rates increased because of the site selection process. I get that the site was selected thanks to an unusual increase in accidents and in that sense the high rate is self-selecting, but it's not the selection process itself that's the actual cause of those accidents, unless I'm missing something obvious.
So something else caused the spike in accidents that caused the site to be selected.
So firstly, you can't just dismiss that increase out of hand as irrelevant, and secondly you can't just assume that speed cameras are the cause of a variation in accident rates after installation.
You're on the right track.So something else caused the spike in accidents that caused the site to be selected.
So firstly, you can't just dismiss that increase out of hand as irrelevant, and secondly you can't just assume that speed cameras are the cause of a variation in accident rates after installation.
Yes you're right, it's not the site selection process that caused the accidents to occur,
but the site selection process tended to choose sites where an "abnormal" number had occurred during the SSP.
Outsite the SSP, the accident rate was "normal".
Hence why there was a sudden increase at the start of the SSP, and then sudden drop back to normal afterwards.
Think of it the other way round.
Imagine you selected sites that had 0 accidents in the last 3 years (so your SSP is the last 3 years).
Now wait some years and draw a graph of the accidents at your sites.
Your sites may have accidents before your SSP and after, but none within your SSP.
If you had a large enough number of sites, you'll find accidents occurred before your SSP at around their "normal" rate, but then they suddenly drop down to zero at the start of your SSP.
Then, at the end of your SSP, accidents suddenly increase back to around their "normal" rate again.
It is not your site selection process that prevented the accidents, it's just that you chose those sites where there hadn't been any during your SSP.
Try it for yourself.
Download the spreadsheet mentioned in my video here:
https://speedcamerareport.files.wordpress.com/2023...
Video: https://www.youtube.com/watch?v=-GqOm-keyss
vonhosen said:
Dave Finney said:
vonhosen said:
If the allegation is that an unintended consequence of the visible camera themselves, is an adverse effect on driver behaviour/safety ...
It's not an "allegation", it's evidence.And the evidence suggests that speed cameras are causing an increase in death and serious injuries.
Have you seen the video, or read the report?
No spike where the camera is then.
Be careful what you wish for.
And perhaps we can also agree that that means we need to run scientific trials to prove what effect they're having.
Only then should we decide what policies to pursue next, along with the evidence required to prove them.
It's good to see agreement every now and again
.vonhosen said:
Dave Finney said:
vonhosen said:
Dave Finney said:
vonhosen said:
If the allegation is that an unintended consequence of the visible camera themselves, is an adverse effect on driver behaviour/safety ...
It's not an "allegation", it's evidence.And the evidence suggests that speed cameras are causing an increase in death and serious injuries.
Have you seen the video, or read the report?
No spike where the camera is then.
Be careful what you wish for.
And perhaps we can also agree that that means we need to run scientific trials to prove what effect they're having.
Only then should we decide what policies to pursue next, along with the evidence required to prove them.
It's good to see agreement every now and again
.The fatal & serious collisions have increased in "particular isolated areas" compared to elsewhere.
Those "particular isolated areas" are called "speed camera sites".
The speed cameras started operating, and fatal & serious collisions rose above the previous mean rate.
My report also checks speed camera sites, against all the other roads.
There is a lot more detail in my report than I could fit into my video.
My report: https://speedcamerareport.co.uk/08_mobile/
heebeegeetee said:
I don't see your report as evidence that cameras are a problem. I see it as evidence that bad driving is a problem, and its just high time that mandatory driver retraining is brought in, in various forms.
People who crash because of a camera or a speed limit sighn are going to crash somewhere sooner or later anyway. I don't want cameras or speed limits removed to assuage bad drivers.
We need bad drivers removed from the roads.
We are, in essence, in agreement.People who crash because of a camera or a speed limit sighn are going to crash somewhere sooner or later anyway. I don't want cameras or speed limits removed to assuage bad drivers.
We need bad drivers removed from the roads.
I am in favour of speed cameras.
I am in favour of trying any new policy that might improve road safety, eg your "mandatory driver retraining".
I too want "bad drivers removed from the roads".
I would like us to achieve no deaths at all on the roads.
But I demand evidence.
Surely you agree with me that we will only ever achieve zero deaths if we ensure that we have the highest standard of evidence?
Video: https://www.youtube.com/watch?v=-GqOm-keyss
rscott said:
vonhosen said:
Dave Finney said:
vonhosen said:
Dave Finney said:
vonhosen said:
Dave Finney said:
vonhosen said:
If the allegation is that an unintended consequence of the visible camera themselves, is an adverse effect on driver behaviour/safety ...
It's not an "allegation", it's evidence.And the evidence suggests that speed cameras are causing an increase in death and serious injuries.
Have you seen the video, or read the report?
No spike where the camera is then.
Be careful what you wish for.
And perhaps we can also agree that that means we need to run scientific trials to prove what effect they're having.
Only then should we decide what policies to pursue next, along with the evidence required to prove them.
It's good to see agreement every now and again
.The fatal & serious collisions have increased in "particular isolated areas" compared to elsewhere.
Those "particular isolated areas" are called "speed camera sites".
The speed cameras started operating, and fatal & serious collisions rose above the previous mean rate.
My report also checks speed camera sites, against all the other roads.
There is a lot more detail in my report than I could fit into my video.
My report: https://speedcamerareport.co.uk/08_mobile/
Or is it only at a few camera sites?
1. What happened to accident rates across the entire TVP area ( not just camera sites). If the overall rate increased by more than that of camera sites, then it suggests cameras are working.
2. How did traffic levels through the camera sites change?
Accident rates should be as percentage of vehicles through the sites to be meaningful comparisons. A road near me has seen a doubling of accidents over the last 4 years, but there have also been 3 new housing developments of about 750 houses built, which has trebled traffic volumes, so the number of accidents per journey has fallen.
and good questions:
1. Yes, my full report compares the accident rates at the camera sites to the accident rates across the entire TVP area.
2. Don't know. I did ask but the speed camera partnership said they never took those speed readings.
You're right, there are a host of factors influencing accident rates across the entire TVP area,
such as traffic volumes, cost of fuel, weather, Police reporting practices, choice of transport mode etc etc.
And these factors should influence accident rates at the camera sites in proportion.
My video doesn't mention "trend" (as they call it), but it is compensated for in my full report.
I use the same concept as official reports,
but I developed a new more accurate method.
My new method has since been adopted and recommended by official road safety researchers.
See graphs 8.2, 8.3 and 8.5 at the end of this page (the 3 graphs that show "Proportions"):
https://speedcamerareport.co.uk/08_mobile_report/
Both of my new methods (for trend and site selection effects (RTM)) are here:
https://speedcamerareport.co.uk/rtm-regression-to-...
heebeegeetee said:
Dave Finney said:
For bringing this back on topic - THANK YOU!
and good questions:
1. Yes, my full report compares the accident rates at the camera sites to the accident rates across the entire TVP area.
2. Don't know. I did ask but the speed camera partnership said they never took those speed readings.
You're right, there are a host of factors influencing accident rates across the entire TVP area,
such as traffic volumes, cost of fuel, weather, Police reporting practices, choice of transport mode etc etc.
And these factors should influence accident rates at the camera sites in proportion.
My video doesn't mention "trend" (as they call it), but it is compensated for in my full report.
I use the same concept as official reports,
but I developed a new more accurate method.
My new method has since been adopted and recommended by official road safety researchers.
See graphs 8.2, 8.3 and 8.5 at the end of this page (the 3 graphs that show "Proportions"):
https://speedcamerareport.co.uk/08_mobile_report/
Both of my new methods (for trend and site selection effects (RTM)) are here:
https://speedcamerareport.co.uk/rtm-regression-to-...
I'm still struggling to see what your point is. :-)and good questions:
1. Yes, my full report compares the accident rates at the camera sites to the accident rates across the entire TVP area.
2. Don't know. I did ask but the speed camera partnership said they never took those speed readings.
You're right, there are a host of factors influencing accident rates across the entire TVP area,
such as traffic volumes, cost of fuel, weather, Police reporting practices, choice of transport mode etc etc.
And these factors should influence accident rates at the camera sites in proportion.
My video doesn't mention "trend" (as they call it), but it is compensated for in my full report.
I use the same concept as official reports,
but I developed a new more accurate method.
My new method has since been adopted and recommended by official road safety researchers.
See graphs 8.2, 8.3 and 8.5 at the end of this page (the 3 graphs that show "Proportions"):
https://speedcamerareport.co.uk/08_mobile_report/
Both of my new methods (for trend and site selection effects (RTM)) are here:
https://speedcamerareport.co.uk/rtm-regression-to-...
Are you saying the roads would be safer without speed limit enforcement?
The ONLY way to do that is to base all our efforts on the highest standard of evidence.
But we are destined to fail.
The primary reason for our failure is that the standard of evidence in official reports is unacceptably weak.
The 1st step in solving a problem, is to recognise that the problem exists.
So my research, my reports and my video are all my attempt to get the authorities to recognise that the problem exists.
And that's just the 1st step.
Then, we can obtain proper evidence (that means running scientific trials).
That will allow us to properly understand the road safety system,
and we can then actually save lives.
I do find it shocking that there is such determined opposition to this!
Video: https://www.youtube.com/watch?v=-GqOm-keyss
heebeegeetee said:
I think the problem was recognised early in the 20th century.
I think the chief problem is that too many people are too stupid, plus an incredibly lax enforcement, plus easy access to motor cars which are barely fit for puropse ie they're unnecessarily fast, heavy, and chock full of distracting s
t. And, there are too many cars on the road and too few alternatives to the car.
If you're telling me that people are crashing so severely that they are killing or seriously injuring themselves or others simply because of the presence of speed enforcement then I'm saying those people are not suited to driving. The problem is far more fundamental than speed enforcement.
Do you propose scientific trials to determine whether people are suited to driving and/or is the driver training and standards programme sufficient?
You've lots of opinions there and maybe you're right on some of them.I think the chief problem is that too many people are too stupid, plus an incredibly lax enforcement, plus easy access to motor cars which are barely fit for puropse ie they're unnecessarily fast, heavy, and chock full of distracting s
t. And, there are too many cars on the road and too few alternatives to the car. If you're telling me that people are crashing so severely that they are killing or seriously injuring themselves or others simply because of the presence of speed enforcement then I'm saying those people are not suited to driving. The problem is far more fundamental than speed enforcement.
Do you propose scientific trials to determine whether people are suited to driving and/or is the driver training and standards programme sufficient?
But others have different opinions, and maybe they're right on some of them.
How do we sort out the policies that work?
Shouldn't we at least try an evidence led approach?
So yes. If you devised a "driver training programme" designed to save lives, it could be tested within a scientific trial.
If it produced the results you hoped for, I suspect you'd suddenly be a keen advocate for evidence!
bigothunter said:
Data provided by Statista sourced from European Commission, shows an 18% increase in fatality rate on German autobahns compared to UK motorways.
Yes, I found that as well.I believe 51% of the autobahn is unrestricted and that report seems to refer to all of the autobahn.
Couldn't find driver miles for the unrestricted autobahn but didn't look in depth.
Also need several years of data to check for outliers.
Evidence is hard work,
but even if you do all the hard work for them, many people still reject the evidence.
Technology has advanced, but our brains are the same as those that believed societies ills can be banished by burning witches.
You got in there before me.
Also, the figure is on a report from another report.
We need to see the original report to check properly.
Found this on EU+ motorways:
https://road-safety.transport.ec.europa.eu/system/...
Also, the figure is on a report from another report.
We need to see the original report to check properly.
Found this on EU+ motorways:
https://road-safety.transport.ec.europa.eu/system/...
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