speed limits: do they work? (of course not)

[Pete317]

Willy Nilly said:

Pete317 said:

Willy Nilly said:

anonymous said:

[redacted]

The reduction in death rates is almost certainly down to crashes in modern vehicles being more survivable than ever before along with better medical practices. By 2000 the NCAP safety ratings on cars was really starting to gain momentum, now 15 years later there arn't many pre 2000 car around without the various safety feaures that make crashing more survivable. But it's lower speed limits/speed cameras that get the credit.

I wonder if they're going to give the credit to the new rash of 20 mph limits for the 12% increase in pedestrian fatalities last year?

https://www.gov.uk/government/uploads/system/uploa...

Edited by Pete317 on Saturday 15th August 22:56

It might be a blip or a couple of bad crashes skewing the figures.

The way the lowering of speed limits are sold is that 40 = certain death, 30 = not bad, 20 = you'll probably sprint away from the incident in better health than before. No matter what speed you get hit at it is going to be traumatic and personally, I'd rather not be hit my a vehicle. People may well be taking more risks in a 20 limit that they would never contemplate in a 30+ limit.

An increase from 398 to 446 looks like a very big blip indeed - especially against the proliferation of 20mph limits, which were touted as the answer to all ills.

[Moonhawk]

Pete317 said:

anonymous said:

[redacted]

As they had done since the 1970's

However, the latest (2014) figures indicate a somewhat worrying change:

https://www.gov.uk/government/uploads/system/uploa...

Interestingly:

"Pedestrians accounted for three quarters of the increase in fatalities between 2013 and 2014. Pedestrian fatalities increased by 12 per cent from 398 in 2013 to 446 in 2014."

I wonder if the powers that be have looked at the relationship between smartphone use and pedestrian accidents? The number of pedestrians I see walking around completely absorbed in their smart phones and with earphones in, apparently oblivious to the world around them is definitely on the increase. I have seen dozens simply cross a junction or walk out into a road without even looking.

The focus in previous years has been on the car/driver - with increased safety measures being mandated in cars and stricter rules/penalties targeting drivers. I think we are reaching the point of diminishing returns. There is only so much you can achieve by targeting drivers.

Perhaps to keep up the momentum of reducing casualty figures, it's time to switch focus and start putting some more onus on pedestrians. Perhaps the highway code should be put on the national curriculum, perhaps we even need US style "jaywalking" offences?

[flemke]

Toltec said:

flemke said:

Do we know that the 90th percentile drivers are less safe driving at that 90th %ile speed than they would be if they were driving at a lower speed?

It is a statistical analysis, it tells you nothing about individuals.

I agree with Von in that the 85th percentile speed is not the maximum safe speed for a road. It is instead in the range that most of the safest drivers choose to use.

Strictly speaking, the 85th percentile would not necessarily be the maximum safe speed for the road, but, for a given driver, it might indeed be the "maximum safe speed for the road". That's if one accepts the idea that there is a "maximum safe speed".

"Maximum safe speed" is, however, a woolly concept. How much "safe" is enough: safe enough for you, or safe enough for me? Safe enough for the Secretary of State for Transportation, or for the local authority, or for "Brake"?

Of course the flaw in speed limits is that the optimal speed will vary by driver, by that driver's mood and physical state at the time, by vehicle, by time of day, by weather, by the situation with other road users at the time, and by which precise bit of the road one is on.

This is why the imposition of the same maximum speed on all drivers in all circumstances does not work as well as would a structure in which drivers are held to a higher than at present driving standard and with that are at liberty to make their own judgments about what is their optimal speed at any given moment.

[Pete317]

Moonhawk said:

I wonder if the powers that be have looked at the relationship between smartphone use and pedestrian accidents? The number of pedestrians I see walking around completely absorbed in their smart phones and with earphones in, apparently oblivious to the world around them is definitely on the increase. I have seen dozens simply cross a junction or walk out into a road without even looking.

With the vast amount of data which is painstakingly gathered by investigators for each and every KSI accident nowadays, you would think they would by now have a very good and detailed picture of what actually causes the accidents.

So why do they seemingly remain so tight-lipped about it?
Why are we still having to guess from basic statistics?

[vonhosen]

anthonym said:

here's a bit about the 85th percentile speed, just googled and scan read.

http://metrocount.com/downloads/flyers/Speed_analy...

It still doesn't say that the 85th percentile speed is the maximum safe speed in optimal conditions.

[Moonhawk]

Pete317 said:

Moonhawk said:

I wonder if the powers that be have looked at the relationship between smartphone use and pedestrian accidents? The number of pedestrians I see walking around completely absorbed in their smart phones and with earphones in, apparently oblivious to the world around them is definitely on the increase. I have seen dozens simply cross a junction or walk out into a road without even looking.

With the vast amount of data which is painstakingly gathered by investigators for each and every KSI accident nowadays, you would think they would by now have a very good and detailed picture of what actually causes the accidents.

So why do they seemingly remain so tight-lipped about it?
Why are we still having to guess from basic statistics?

Yep - also given the fact that kids age 12 are the most at risk, why isn't the highway code on the national curriculum and drummed into them at school? There don't appear to be any high profile public information campaigns (e.g. green cross code) targeting kids like there was for us growing up in the 1970s and 1980s.

[tapereel]

Toltec said:

flemke said:

Do we know that the 90th percentile drivers are less safe driving at that 90th %ile speed than they would be if they were driving at a lower speed?

It is a statistical analysis, it tells you nothing about individuals.

I agree with Von in that the 85th percentile speed is not the maximum safe speed for a road. It is instead in the range that most of the safest drivers choose to use.

I think the 85th percentile speed figure is too often and unjustifiably embellished with the "safest driver" phrase. The 85th percentile speed is simply that, there is no guarantee or suggestion that the drivers choosing that speed are the safest. I have corrected your comment above to the most accurate description of the 85th percentile speed.

[flemke]

tapereel said:

Toltec said:

flemke said:

Do we know that the 90th percentile drivers are less safe driving at that 90th %ile speed than they would be if they were driving at a lower speed?

It is a statistical analysis, it tells you nothing about individuals.

I agree with Von in that the 85th percentile speed is not the maximum safe speed for a road. It is instead in the range that most of the safest drivers choose to use.

I think the 85th percentile speed figure is too often and unjustifiably embellished with the "safest driver" phrase. The 85th percentile speed is simply that, there is no guarantee or suggestion that the drivers choosing that speed are the safest. I have corrected your comment above to the most accurate description of the 85th percentile speed.

Analyses have consistently shown that the drivers whose speed is roughly at the 85th percentile of the speeds of all drivers in a given set of conditions tend to have the lowest accident rate.

Agreed, there is no guarantee that driving at that speed will make you the safest, but, at the same time, there certainly is the suggestion that "the drivers choosing that speed are the safest".

You can argue whether it is that level of relative speed that makes them the safest, but, for whatever reasons, the data certainly do suggest that those in the 85th %ile cohort are the safest.

[vonhosen]

flemke said:

tapereel said:

Toltec said:

flemke said:

Do we know that the 90th percentile drivers are less safe driving at that 90th %ile speed than they would be if they were driving at a lower speed?

It is a statistical analysis, it tells you nothing about individuals.

I agree with Von in that the 85th percentile speed is not the maximum safe speed for a road. It is instead in the range that most of the safest drivers choose to use.

I think the 85th percentile speed figure is too often and unjustifiably embellished with the "safest driver" phrase. The 85th percentile speed is simply that, there is no guarantee or suggestion that the drivers choosing that speed are the safest. I have corrected your comment above to the most accurate description of the 85th percentile speed.

Analyses have consistently shown that the drivers whose speed is roughly at the 85th percentile of the speeds of all drivers in a given set of conditions tend to have the lowest accident rate.

Agreed, there is no guarantee that driving at that speed will make you the safest, but, at the same time, there certainly is the suggestion that "the drivers choosing that speed are the safest".

You can argue whether it is that level of relative speed that makes them the safest, but, for whatever reasons, the data certainly do suggest that those in the 85th %ile cohort are the safest.

But it doesn't suggest that it isn't safe for a different individual to exceed the 85th percentile speed. (Ergo the 85th percentile can't be said to define what the maximum safe speed is).

[flemke]

vonhosen said:

flemke said:

tapereel said:

Toltec said:

flemke said:

Do we know that the 90th percentile drivers are less safe driving at that 90th %ile speed than they would be if they were driving at a lower speed?

It is a statistical analysis, it tells you nothing about individuals.

I agree with Von in that the 85th percentile speed is not the maximum safe speed for a road. It is instead in the range that most of the safest drivers choose to use.

I think the 85th percentile speed figure is too often and unjustifiably embellished with the "safest driver" phrase. The 85th percentile speed is simply that, there is no guarantee or suggestion that the drivers choosing that speed are the safest. I have corrected your comment above to the most accurate description of the 85th percentile speed.

Analyses have consistently shown that the drivers whose speed is roughly at the 85th percentile of the speeds of all drivers in a given set of conditions tend to have the lowest accident rate.

Agreed, there is no guarantee that driving at that speed will make you the safest, but, at the same time, there certainly is the suggestion that "the drivers choosing that speed are the safest".

You can argue whether it is that level of relative speed that makes them the safest, but, for whatever reasons, the data certainly do suggest that those in the 85th %ile cohort are the safest.

But it doesn't suggest that it isn't safe for a different individual to exceed the 85th percentile speed. (Ergo the 85th percentile can't be said to define what the maximum safe speed is).

Quite so. It's not the speed itself.

It does, however, raise the question of what is it that makes that group, the ones who end up being at the 85th %ile of speed, the safest drivers.

[Funkycoldribena]

Pie charts,we need more pie charts...

[Toltec]

flemke said:

Quite so. It's not the speed itself.

It does, however, raise the question of what is it that makes that group, the ones who end up being at the 85th %ile of speed, the safest drivers.

Experience, ability and self-control.

I think you would need to add in a desire to optimize the use of the road and be at a comfortable work rate. Some drivers meeting the criteria of the first line will be happy driving more slowly of course.

[anthonym]

Pete317 said:

Moonhawk said:

I wonder if the powers that be have looked at the relationship between smartphone use and pedestrian accidents? The number of pedestrians I see walking around completely absorbed in their smart phones and with earphones in, apparently oblivious to the world around them is definitely on the increase. I have seen dozens simply cross a junction or walk out into a road without even looking.

With the vast amount of data which is painstakingly gathered by investigators for each and every KSI accident nowadays, you would think they would by now have a very good and detailed picture of what actually causes the accidents.

So why do they seemingly remain so tight-lipped about it?
Why are we still having to guess from basic statistics?

Yes I too find that very frustrating. Whenever I pass an accident spot I always wonder what happened, how and why. Yet whenever I look for the information it's just not available; except as interpreted by someone else, which is of no help at all to me. I have here the entire database of UK 2014 accident data and, while some of it really is heart wrenching (looking at the death stats of the very young) and while it is interesting to analyse the data, it still doesn't really tell me what happened. Assuming a perfectly capable driver, how on Earth did they find themselves involved? Vague responses don't help, such as "go more slowly", which as far as I can see in most cases would not have prevented the crash. And "crashing more slowly" isn't accident prevention, it's just a counsel of despair in the absence of real solutions, which seems to me if drivers are excluded from the knowledge of what happens, is not going to change.

If anyone wants the stats I'll find where I got them from; there are hoops (not insurmountable) to jump through and I am not allowed to simply share the data - which is frustrating in itself. It's available for Excel, in CSV. It's a huge amount of data and argument rages about how accurate it is based on forms completed by the police STATS 19 I think it is.

Anthony


edit to add:

http://ukdataservice.ac.uk/

Study Number 7752 - Road Accident Data, 2014

Edited by anthonym on Sunday 16th August 14:29

[number 46]

Pete317 said:

So why do we still have the constant push for lower speed limits, more enforcement, more traffic calming, more blanket 20mph limits etc?

Revenue and to satisfy the needs of the left to control every aspect of people's lives.

[anthonym]

tapereel said

"Police and councils benefit only by the offender paying for the enforcement costs. Quite frankly I think that is exactly who should pay, not you and not me. What a great shame offenders committing other types of offences cannot pay the costs of detection and disposal of their offences. That would relieve council tax and income tax payers of a massive burden. There should be a new set of laws to enable this."

end quote

My thoughts about this:

We have a three part constitution, the legislature, the courts and the police. Each is independent of the others and that separation underpins our society's freedoms.

I am rather uncomfortable with this concept:

" Police and councils benefit only by the offender paying ..." especially when the word "only" is omitted from the sentence.Then we have "Police and councils benefit ... by the offender paying... ". There is a very short step from "benefit" to "profit" when we read this: "Police and councils profit only by the offender paying..."

One can reasonably argue that "benefit" and "profit" are interchangeable; in tax law this is well established and taxed.

The idea of ANY arm of the pillars of our constitution profiting from crime is I think fatally flawed. These pillars of society must not only be, but they must be seen to be completely free of inappropriate influence or motivation. I am tempted to say especially the police who need to be whiter than white if they are to be respected by society as a whole. The idea that police profit from speed enforcement is already a genie long out of the bottle. Rightly or wrongly.

I am not going so far as to say that fines are the proceeds of crime, but it is not a giant leap if the legislative and the police are benefiting as quoted above.

I quite see the temptation of the idea of criminals literally paying for their crimes, but seems to be it is a very slippery constitutional slope especially also where the courts are excluded - which is the reality; this is "due process denied".

All fraught with problems, despite the apparent attraction of logic by those involved.

Anthony

[vonhosen]

anthonym said:

tapereel said

"Police and councils benefit only by the offender paying for the enforcement costs. Quite frankly I think that is exactly who should pay, not you and not me. What a great shame offenders committing other types of offences cannot pay the costs of detection and disposal of their offences. That would relieve council tax and income tax payers of a massive burden. There should be a new set of laws to enable this."

end quote

My thoughts about this:

We have a three part constitution, the legislature, the courts and the police. Each is independent of the others and that separation underpins our society's freedoms.

I am rather uncomfortable with this concept:

" Police and councils benefit only by the offender paying ..." especially when the word "only" is omitted from the sentence.Then we have "Police and councils benefit ... by the offender paying... ". There is a very short step from "benefit" to "profit" when we read this: "Police and councils profit only by the offender paying..."

One can reasonably argue that "benefit" and "profit" are interchangeable; in tax law this is well established and taxed.

The idea of ANY arm of the pillars of our constitution profiting from crime is I think fatally flawed. These pillars of society must not only be, but they must be seen to be completely free of inappropriate influence or motivation. I am tempted to say especially the police who need to be whiter than white if they are to be respected by society as a whole. The idea that police profit from speed enforcement is already a genie long out of the bottle. Rightly or wrongly.

I am not going so far as to say that fines are the proceeds of crime, but it is not a giant leap if the legislative and the police are benefiting as quoted above.

I quite see the temptation of the idea of criminals literally paying for their crimes, but seems to be it is a very slippery constitutional slope especially also where the courts are excluded - which is the reality; this is "due process denied".

All fraught with problems, despite the apparent attraction of logic by those involved.

Anthony

You can't escape it.

Fines go to public funds, the Police are funded from public funds.
Government controls the funding they get from public funds

[Toltec]

anthonym said:

here's a bit about the 85th percentile speed, just googled and scan read.

http://metrocount.com/downloads/flyers/Speed_analy...

The 4 second headway is interesting, on an single carriageway if I am within four seconds of another vehicle they could already be affecting how I am driving.

[anthonym]

vonhosen said:

You can't escape it.

Fines go to public funds, the Police are funded from public funds.
Government controls the funding they get from public funds

You are of course at liberty to generalise as you wish, but you are just not in control of how other's view it.

[vonhosen]

anthonym said:

vonhosen said:

You can't escape it.

Fines go to public funds, the Police are funded from public funds.
Government controls the funding they get from public funds.

You are of course at liberty to generalise as you wish, but you are just not in control of how other's view it.

An individual's perception doesn't alter 'the' reality.

[tapereel]

anthonym said:

vonhosen said:

You can't escape it.

Fines go to public funds, the Police are funded from public funds.
Government controls the funding they get from public funds

You are of course at liberty to generalise as you wish, but you are just not in control of how other's view it.

Well in your post above you are viewing the funding as the authorities "profiting" but you have of course omitted to mention how much the activity costs the authorities.
Profit can only be calculated by considering revenues and costs and you have not done that so your opinion is flawed.