The new Average speed cameras on the A40 /westway West Lond

The new Average speed cameras on the A40 /westway West Lond

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TwigtheWonderkid

43,248 posts

149 months

Saturday 29th August 2015
quotequote all
That doesn't alter the fact that the lower the speed, the less the danger. I agree that on a deserted m/way, cars will travel and 100mph, 90, 70 and 50. And most of the time nothing will happen to any of them. But when something goes wrong, in what circumstances would you rather be going faster?

I don't think there's any doubt that if vehicles were restricted to 5 mph, the death and serious injury tally would drop to virtually nil. I'm not advocating that as the way forward by the way.


Dave Finney

380 posts

145 months

Saturday 29th August 2015
quotequote all
TwigtheWonderkid said:
That doesn't alter the fact that the lower the speed, the less the danger. I agree that on a deserted m/way, cars will travel and 100mph, 90, 70 and 50. And most of the time nothing will happen to any of them. But when something goes wrong, in what circumstances would you rather be going faster?

I don't think there's any doubt that if vehicles were restricted to 5 mph, the death and serious injury tally would drop to virtually nil. I'm not advocating that as the way forward by the way.
I agree that "slower = safer" sounds plausible but the data suggests it's not true in practice. The evidence suggests that we are involved in more serious injury collisions when we are within the speed limit, compared to when we are speeding.

It seems that road safety has many factors and these factors are interconnected. If we change one, then others change as a result. Eg, starting from our "natural safe speed", if we go faster then we tend to concentrate more. The increase in speed tends to increases crash risk, while the increase in concentration tends to reduce crash risk. Likewise, if we slow down (from our "natural safe speed"), we tend to concentrate less, thereby increasing our chance of crashing. And that's before considering other road users interaction with unusually fast or slow vehicles.

But what interests me is not the theory, it's the actual effects of speed cameras on the number of people killed and seriously injured. The problem I found was that the authorities haven't produced any good quality evidence of any benefit and, because no-one else looked likely to do it, it seemed that I would have to.

To end the debate, all we have to do is run speed cameras within scientific trials and the jobs done!
http://speedcamerareport.co.uk/02_scientific_trial...

TwigtheWonderkid

43,248 posts

149 months

Sunday 30th August 2015
quotequote all
Dave Finney said:
TwigtheWonderkid said:
That doesn't alter the fact that the lower the speed, the less the danger. I agree that on a deserted m/way, cars will travel and 100mph, 90, 70 and 50. And most of the time nothing will happen to any of them. But when something goes wrong, in what circumstances would you rather be going faster?

I don't think there's any doubt that if vehicles were restricted to 5 mph, the death and serious injury tally would drop to virtually nil. I'm not advocating that as the way forward by the way.
I agree that "slower = safer" sounds plausible but the data suggests it's not true in practice. The evidence suggests that we are involved in more serious injury collisions when we are within the speed limit, compared to when we are speeding.
I think you are missing my point.

I'm sure you are right, and more people are killed or injured by cars doing 29mph in a 30 than by cars doing 80mph in a 70.

That doesn't alter the fact that lower speeds mean less danger. I'd rather be hit by a car doing 20 in a 30 than by one doing 29 in a 30.

If you knew you were going to have a crash tomorrow whilst driving and could choose in advance the speed you would be doing when you had it, what speed would you choose? I'd choose 1mph.

V8 Fettler

7,019 posts

131 months

Sunday 30th August 2015
quotequote all
TwigtheWonderkid said:
V8 Fettler said:
TwigtheWonderkid said:
number 46 said:
You are no more in danger driving past a yellow box on a post at 40 or 44,
Well that's not true. By and large, the faster you're going, the greater the danger. If an incident unfolds in front of me, I'd rather be doing 40 than 44.


If there's so little difference between 40 and 44 as you state, then just do 40 and avoid prosecution.
This has been covered endlessly: is not 80mph on a deserted m/way safer (by and large) than 29mph in most urban situations?
Maybe. What is certain is that 80mph on a deserted m/way isn't as safe as 70mph on a deserted m/way. And 29mph in urban driving isn't as safe as 25mph.

On a deserted m/way you could have a blowout, or some catastrophic mechanical failure, or a deer could run out. I can't think of a situation where you'd say, after the event, "I wish I'd been going faster."
The chances of a tyre blowout or mechanical failure causing a modern, well-maintained car to crash on a motorway must be vanishingly small, do you have any data?

Correct use of speed and acceleration can reduce risk, e.g. overtaking, joining from a minor road or slip. Awareness of road conditions and the likely actions of other road users is more important than blindly following unnecessarily restrictive speed limits. My perception is that I am safer making good progress at 90mph in lane 4 than trundling at 60mph in lane 2 avoiding the lorries swerving towards me.

The real issues are driver competence and road design/maintenance. If we follow your reduced speed concept to a logical conclusion then the national speed limit will be about 40mph on m/ways and 20mph on all other roads.

TwigtheWonderkid

43,248 posts

149 months

Sunday 30th August 2015
quotequote all
V8 Fettler said:
My perception is that I am safer making good progress at 90mph in lane 4 than trundling at 60mph in lane 2 avoiding the lorries swerving towards me.
Agreed, but the example given was a deserted motorway, so your lorry scenario doesn't fit. On a deserted motorway, would you not be safer at 60 than 90?

V8 Fettler said:
If we follow your reduced speed concept to a logical conclusion then the national speed limit will be about 40mph on m/ways and 20mph on all other roads.
If safety were the only consideration, then it would be lower than that. But safety has to be balanced up with having a functioning economy and moving people and goods around, so the powers that be have decided the current limits are the best compromise.

Dave Finney

380 posts

145 months

Sunday 30th August 2015
quotequote all
TwigtheWonderkid said:
Dave Finney said:
TwigtheWonderkid said:
That doesn't alter the fact that the lower the speed, the less the danger. I agree that on a deserted m/way, cars will travel and 100mph, 90, 70 and 50. And most of the time nothing will happen to any of them. But when something goes wrong, in what circumstances would you rather be going faster?

I don't think there's any doubt that if vehicles were restricted to 5 mph, the death and serious injury tally would drop to virtually nil. I'm not advocating that as the way forward by the way.
I agree that "slower = safer" sounds plausible but the data suggests it's not true in practice. The evidence suggests that we are involved in more serious injury collisions when we are within the speed limit, compared to when we are speeding.
I think you are missing my point.

I'm sure you are right, and more people are killed or injured by cars doing 29mph in a 30 than by cars doing 80mph in a 70.

That doesn't alter the fact that lower speeds mean less danger. I'd rather be hit by a car doing 20 in a 30 than by one doing 29 in a 30.

If you knew you were going to have a crash tomorrow whilst driving and could choose in advance the speed you would be doing when you had it, what speed would you choose? I'd choose 1mph.
I agree with you. In a theoretical world, if speeds are lowered and nothing else changes, there will be fewer collisions. This is correct.

But the real world is different. If speeds are lowered in the real world then other factors will change as a result, and some of these will increase risk (Eg, snow and ice will result in lower speeds but might increase crash risk). The question for me (as an engineer) is "what actually happens". The official evidence on "speed management" policies is generally inaccurate and often misleading. Yet all we have to do to find the truth is to run all interventions in scientific trials (where possible).

TwigtheWonderkid

43,248 posts

149 months

Sunday 30th August 2015
quotequote all
I drove into and back from town today on the A40, and even on a Sunday there aren't very many opportunities to exceed the posted limit anyway due to weight of traffic.

I can see it being a bit of a bind coming home from a night out at 3am, when in the past I would usually exceed the limit between cameras, but that aside, I'm not too bothered.

smashy

Original Poster:

3,030 posts

157 months

Sunday 30th August 2015
quotequote all
Ive just come back to london via A40..unless they up the signage if you dont watch forums like this,then I think a lot are going to be caught.So its 50 around Ruislip yet The Westway is 40mph,crazy and all very frustrating when empty roads

Richard Cranium

3 posts

108 months

Sunday 30th August 2015
quotequote all
Dave Finney said:
There are now over 7 average speed cameras on the A40 into and out of London.

The way they work is:
each camera sends video to a computer
the computer scans the video looking for number plates
when it sees one it:
1) records the picture
2) reads and records the registration number
3) records the time

So, for each camera, there's a picture of every vehicle that passed, with it's No plate and the time.

The computers then subtract the times of each vehicle between cameras and, knowing the distance between each camera, they can see if any vehicle reached a following camera in a time shorter than is allowed. If so, that vehicle must have travelled faster than the limit.

Note, it doesn't matter what speed you pass each camera. You could do 80mph past every camera and you shouldn't be prosecuted for speeding, so long as you stop for a while in between each pair of cameras!

You'll also note that every single vehicle is photographed, speeding or not, time and time again as it travels. This means the authorities know where every single vehicle was, and when it was there, day or night, all of the time. They might also see from the photographs how many occupants in each vehicle, age, sex, descriptions etc. This can be very useful to track terrorists, criminals, demonstrators, activists, political opposition groups, and anyone else the authorities may wish to monitor.
As someone who previously worked in a Police Control Room and is trained in the use of ANPR for a fast-time intelligence profile, I can honestly say this isn't even a factor for TfL. One of the best things about ANPR from an investigation perspective was the fact that 99% of the cameras feeding into the NADC are vehicle front-facing, meaning you can say with some certainty who was in the vehicle at the time (usually on the front, in good lighting, when the scrotes don't use the sun visors).

The fact that the cameras on the A40 are vehicle rear-facing tells its own story. For the benefit of the cameras effecting an extra 1% of road users, namely motorcyclists, TfL have sacrificed what could have been a useful addition of ANPR cameras on a major arterial route through West London.

Credit where credit is due, it has certainly kept me at 45-ish for the past month or so, on my bike where front-facing cameras wouldn't have, but don't try and justify their installation by saying they are a useful tool for law enforcement. It's all about revenue, or as it's corporately branded, 'road safety'.

V8 Fettler

7,019 posts

131 months

Monday 31st August 2015
quotequote all
TwigtheWonderkid said:
V8 Fettler said:
My perception is that I am safer making good progress at 90mph in lane 4 than trundling at 60mph in lane 2 avoiding the lorries swerving towards me.
Agreed, but the example given was a deserted motorway, so your lorry scenario doesn't fit. On a deserted motorway, would you not be safer at 60 than 90?

V8 Fettler said:
If we follow your reduced speed concept to a logical conclusion then the national speed limit will be about 40mph on m/ways and 20mph on all other roads.
If safety were the only consideration, then it would be lower than that. But safety has to be balanced up with having a functioning economy and moving people and goods around, so the powers that be have decided the current limits are the best compromise.
Quote dissection, hurrah!

The 60mph in lane 2 vs 90mph in lane 4 comparison was to demonstrate that there are situations where the increase in risk arises from being in closer proximity to lorries rather than an increase in risk arising from an increase in speed. My perception is that I would be safer travelling 180 miles at 90 mph on a deserted motorway rather than travel the same distance at 60 mph due to increased risk of losing concentration during the increased journey time at 60 mph.

There was a time (but not in this century) when I had some trust in the competence of the "Powers that be", that trust has long gone.





robinessex

11,046 posts

180 months

Tuesday 1st September 2015
quotequote all
Shaoxter said:
Why, just WHY???!!!
Safety cameras have proved successful in reducing road casualties in recent years. At locations where safety cameras operate in the capital, research shows that the number of people killed or seriously injured (KSI) fell by an average of 58 per cent, meaning that the cameras help to prevent 500 deaths or serious injuries each year.


Didn't you know that ?

V8 Fettler

7,019 posts

131 months

Tuesday 1st September 2015
quotequote all
robinessex said:
Shaoxter said:
Why, just WHY???!!!
Safety cameras have proved successful in reducing road casualties in recent years. At locations where safety cameras operate in the capital, research shows that the number of people killed or seriously injured (KSI) fell by an average of 58 per cent, meaning that the cameras help to prevent 500 deaths or serious injuries each year.


Didn't you know that ?
Is a "safety" camera a speed camera, a red light camera or both?

robinessex

11,046 posts

180 months

Tuesday 1st September 2015
quotequote all
Safety camera is the official description. So there, behave yourself !!!!

Shaoxter

4,048 posts

123 months

Tuesday 1st September 2015
quotequote all
robinessex said:
Shaoxter said:
Why, just WHY???!!!
Safety cameras have proved successful in reducing road casualties in recent years. At locations where safety cameras operate in the capital, research shows that the number of people killed or seriously injured (KSI) fell by an average of 58 per cent, meaning that the cameras help to prevent 500 deaths or serious injuries each year.


Didn't you know that ?
I don't mind speed cameras in well placed areas where they have the potential to reduce accidents. I drive around the A406 a lot and I welcome the cameras in a lot of places, e.g. there's a camera just after the East Finchley cemetery tunnel westbound which stops crazy people (like me) blasting through the tunnel and possibly rear ending into the queue at the lights at the big A1 junction. But there isn't a camera pointing eastbound so I can usually always make some nice tunnel noise on a journey biggrin Now that's well thought out planning, but I can't see these average speed cameras on the A40 reducing accidents.

schmunk

4,399 posts

124 months

Tuesday 1st September 2015
quotequote all
Shaoxter said:
I can't see these average speed cameras on the A40 reducing accidents.
Maybe they will, maybe they won't but it's surely worth a try....

https://www.google.co.uk/search?q=a40+westway+cras...

The Wookie

13,909 posts

227 months

Tuesday 1st September 2015
quotequote all
schmunk said:
Shaoxter said:
I can't see these average speed cameras on the A40 reducing accidents.
Maybe they will, maybe they won't but it's surely worth a try....

https://www.google.co.uk/search?q=a40+westway+cras...
Top three results there:

1. Motorcyclist has an accident because of a failed expansion joint

2. Video of aftermath of an accident which is most likely someone cutting across another vehicle to take an exit at the last minute and getting spun into the divider

3. A man has a hypoglycaemic episode and has an accident.

I'm not saying Speed Cameras are never useful in reducing road deaths, but people do seem to assume that every accident is down to speed. Yes going slower reduces the consequences but it's not the be all and end all of car accidents.

number 46

1,019 posts

247 months

Tuesday 1st September 2015
quotequote all
The Wookie said:
Top three results there:

1. Motorcyclist has an accident because of a failed expansion joint

2. Video of aftermath of an accident which is most likely someone cutting across another vehicle to take an exit at the last minute and getting spun into the divider

3. A man has a hypoglycaemic episode and has an accident.

I'm not saying Speed Cameras are never useful in reducing road deaths, but people do seem to assume that every accident is down to speed. Yes going slower reduces the consequences but it's not the be all and end all of car accidents.
This is exactly my point. none of these accidents were caused by speeding. None of these accidents would have been prevented by these new cameras.

What is more likely to cause an accident? me driving at 45 mph down an empty 3 lane A40 at 0700 on a Sunday morning or the 3 eastern europeans driving their battered VW Jetta this morning whilst the driver smoked a joint??? Will the hundreds of thousands spent covering 13 miles of the A40 with Average speed cameras help or would having a few more traffic cars patrolling help??

V8 Fettler

7,019 posts

131 months

Tuesday 1st September 2015
quotequote all
robinessex said:
Safety camera is the official description. So there, behave yourself !!!!
Are you not going to tell us if "safety camera" means speed camera, red light camera or both? It's almost as if you're trying to confuse the issue.

Dave Finney

380 posts

145 months

Tuesday 1st September 2015
quotequote all
robinessex said:
Shaoxter said:
Why, just WHY???!!!
Safety cameras have proved successful in reducing road casualties in recent years. At locations where safety cameras operate in the capital, research shows that the number of people killed or seriously injured (KSI) fell by an average of 58 per cent, meaning that the cameras help to prevent 500 deaths or serious injuries each year.


Didn't you know that ?
That's a quote from Transport for London's (TfL) website but it is misleading and/or false. What TfL don't tell their citizens is that the 58% KSI reduction was not due to the speed cameras but was due to a combination of several factors, the largest of which is probably site-selection effects (or RTM). TfL have not measured any of the factors therefore we don't know if the KSI reduction would have been greater without the speed cameras, lower, or if it would have been the same.

This problem is easy to resolve. All TfL have to do is deploy their speed cameras within simple scientific trials:
http://speedcamerareport.co.uk/02_scientific_trial...
Note: the A40 average speed cameras could easily have been deployed within a scientific trial, but TfL decided against performing proper tests.

V8 Fettler

7,019 posts

131 months

Tuesday 1st September 2015
quotequote all
Dave Finney said:
robinessex said:
Shaoxter said:
Why, just WHY???!!!
Safety cameras have proved successful in reducing road casualties in recent years. At locations where safety cameras operate in the capital, research shows that the number of people killed or seriously injured (KSI) fell by an average of 58 per cent, meaning that the cameras help to prevent 500 deaths or serious injuries each year.


Didn't you know that ?
That's a quote from Transport for London's (TfL) website but it is misleading and/or false. What TfL don't tell their citizens is that the 58% KSI reduction was not due to the speed cameras but was due to a combination of several factors, the largest of which is probably site-selection effects (or RTM). TfL have not measured any of the factors therefore we don't know if the KSI reduction would have been greater without the speed cameras, lower, or if it would have been the same.

This problem is easy to resolve. All TfL have to do is deploy their speed cameras within simple scientific trials:
http://speedcamerareport.co.uk/02_scientific_trial...
Note: the A40 average speed cameras could easily have been deployed within a scientific trial, but TfL decided against performing proper tests.
That's all rather damning, there would have been a time when the AA or the RAC would have taken this up with the Minister for Transport.