Safe Speed Forums

I would question that one as well. I can't identify any plausible reason why that should be and, in any case, my personal observations indicate the opposite.
There's a road I've been travelling every day for the past seven years (the A417 between Gloucester and Cirencester). For the first few years the traffic flowed relatively freely, and there were seldom any hold-ups. Then they introduced a 40mph speed limit for about half a mile. Ever since then, stop-start traffic has become a daily occurrence, and long tailbacks are frequent.

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Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

Not so much philosophy as an attempt to get to the root of the basis of people's decision making, and the accuracy of this.



Agreed - but I'm not sure how relevant that is to my point.



It was worded awkwardly, apologies for that.

My question related to the knowledge of the driver at any point where they could have averted the accident. Did they know they were going to crash at any of those points? Did they know of all of the factors which conspired to create the accident at any of those points?



Essentially my point is we all have different standards, and different ideas of "acceptable risk", "knowledge", "fact", "reasonable certainty" and so on. Yet our actions on the road pose varying degrees of risk to others as well as ourselves - and there is a conflict where one person creates a risk that is considered "acceptable" by themselves but may not be considered "acceptable" by others who are also subject to that risk.



Agreed



I think thats simplistic. Making one hazard obvious may drown out other hazards - but if you don't make it obvious it may not be easy enough to perceive. And if you try and make a subtle hazard obvious and drivers see the effort to make the hazard easy to perceive but do not see the hazard itself, it is unlikely that making the hazard easy to perceive would actually help (indeed, if the hazard is of greater magnitude than it appears, this may be counter productive).

There is probably an optimal situation - but we can't make all hazards easy to perceive.



Agree with all of that



Whilst the 85%ile is a useful tool of evaluating how fast drivers believe is appropriate (it is essentially consultation by stealth), it doesn't take into account anything other than drivers opinions.

If we assume the 85%ile is an appropriate speed for drivers to travel at, then what would setting the limit at that speed achieve?



Agreed, where that is appropriate.



Should drivers be legally obliged to comply with the maximum speed limit? What action would be appropriate against any driver failing to comply with these limits?

(Again, this is all questions and not alot of answers, but its not an attempt to make or answer a point - rather to establish an appropriate way forward).

How did you arrive at that conclusion from anything I have said?

We're having quite a useful exercise here. I don't think wading in with false dichotomies is especially helpful.

As discussed in the other thread, speed is a factor

http://www.safespeed.org.uk/forum/viewtopic.php?p=70230#70230



But then, am I right?

Asking "are they right" is part of my point I was asking Paul - are drivers always right when setting their speed?



There is somewhat more to it than that (though damage limitation is an issue)



True of anything.



To which the only solution is them driving while inexperienced - so there will always be inexperienced drivers.

and attention.



Absolutely.

Thats also why its important to ensure drivers are driving at a speed such that they can be "reasonably certain" that the distance ahead in which they can stop will clear when they get to it.

This (and all that followed it) is sound advice, and I have read Roadcraft.

However, thats not really relevant to the question I was (trying to) ask

That's a moot point.
If you're not paying attention to the road ahead then there's no speed above zero mph from which you can be reasonably certain of being able to stop within the distance you know to be clear.

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Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

Well yes, thats obvious.

Whats your point?

The point to which you made that reply was made within the context of inattentive driving.

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Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

Accuracy is a good target for improvement - that is where lives can be saved.

We start with 'perfect', then look at the shortfalls and try to minimise them. But we have to be accurate about the definition of 'perfect', and of course we have to chose the right targets for improvement.

The 'modern' idea that 'driver error is inevitable and uncontrollable' misses the excellent opportunity to build on our greatest strengths. And there's OODLES of room for improvement.



We depend on the knowledge of any individual who - at that instant - has responsibility for controlling risk. Differences of opinion are a complete irrelevance.

I can see where you're coming from - external controls will minimise the risk when an individual makes a knowledge or assessment error. But it isn't even remotely realistic applied population-wide.

The external controls need to be targeted, not at the system as a whole, but at those parts (individuals?) which fail. If we target external controls against non-failing parts of the system - it can't fail less - we can only expect to make it fail MORE.

That may well be the crux of it.



This is really what I just covered above.



Since (as above again) we depend on drivers to manage risk, and since they are on the whole, amazingly effective, nothing other than drivers' opinions is a genuine safety issue (in all normal circumstances).

You have to stop concentrating on the failures and concentrate on the successes.

I don't know if this is a good analogy, but think of road safety as a retail store. If we're going to maximise profitability we'll concentrate on the lines that are selling well - we won't get obssessed working to get more sales of lines in which the public show no interest. It would be stupid indeed to fill the window with our worst selling lines...



See the list of three.



Yes.

Enforcement of real safety violations, with slightly higher penalties than we have now. Of course we then need a system that can distinguish between technical-only violations and real safety violations. That system is called 'Police Traffic Officers'.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Well I intended to refer specifically to "a car travelling at just 30mph covers 44 feet in one second", though this wasn't clear. After all, if the driver simply drives faster so that their extra second's attention is simply removing a second of time to react, we haven't got anywhere.

Yes



Nevertheless, you can't ignore driver error - especially at sites where a significant number of drivers are making erros.



Maybe so - but the people holding the differing opinions will disagree. So do you just ignore them?



Why not?



Why not the circumstances in which they fail?



Maybe so - so whats wrong with targeting people's decision making when it comes when they are failing to choose an appropriate speed?




Isn't this important?




I kinda see what you're getting at - but how would this apply at an accident site? What would you do to look on successes instead of failures?





Surely if you only intend to prosecute "dangerous" speeding offenses, you are essentially enacting an advisory system which provides a means of prosecuting "dangerous" speeds over the limit but where others travelling over the limit are not prosecuted?

And surely if the limits are properly set, the difference between techinical and safety violations will be minimal?

And how far would this apply to other traffic laws?

I see driver errror as 'an absence of good driving' - driver errors are mostly sins of omission. (Attitude problems are the other large class.)

I was also talking about the wider system rather than site-specific issues. If a certain site has a significant number of drivers making the same sort of error, then engineering site treatment is indicated (of course).

I generally think we're (national we're) much closer to optimal with site treatments, while we're very far from optimal with system treatments. In fact we're so far from optimal we're making it worse. And unfortunately the faulty system treatments are also applied at site level.



Educate them.





Already answered before asked - right here:






Nothing. That would be excellent. It amounts to a system treatment with an appropriate focus.



I missed it - but I'm guessing you'll know my answer by now anyway.

Crashes are most likely when opportunities to know are missed. For example when a road user fails to look or fails to see.



I guess it means you would try to make it more like sites that didn't have the problem. You might think you are designing out failure, but perhaps you're really importing success?

But I was again really thinking about the road safety system as a whole. The risks of damaging success are much smaller when there's a genuine local problem to solve.



Because they cannot distinguish between safe and dangerous behaviours and because they have massively damaging side effects.




It's a system that we had up until the early 1990s. I don't think anyone thought it was 'advisory'.



<boggle> You cannot be serious! Conditions change from second to second and yard to yard. Drivers must take account of constantly varying conditions - speed limits cannot do this.



I cannot think of another 'black and white' traffic law that is endlessly grey in practice. If there was one, I'd probably make the same suggestion.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Agreed



So would is the problem with speed cameras as a remedial measure?




How do you propose we do that? Don't forget not all the people who have an interest in the level of risk on the road have driving licences.




Drink driving re blood alcohol levels?

Weight limits?

But in neither case do the police routinely turn a blind eye to what they know to be offending in a technical sense.

Also, in the case of drink driving, responsible drivers do not normally operate on the margins of legality, as they do with speed limits.

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"Show me someone who says that they have never exceeded a speed limit, and I'll show you a liar, or a menace." (Austin Williams - Director, Transport Research Group)

Any views expressed in this post are personal opinions and may not represent the views of Safe Speed

Exceeding weight limits will generally result in an unacceptable level of road wear or risk of structural damage.
The life expectancy of a road surface, for instance, is almost directly (inversely) related to around the fourth power of axle weight - which leaves little in the way of grey area.

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Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

Fifth power actually.

But one might apply a similar argument to speed limits because at impact there's supposed to be a 4th power relationship between delta V and fatality risk.

Of course we know that crash delta V isn't a function of free travelling speed in any realistic sense - but I thought I'd head the argument off at the pass.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Of course, we also know that free travelling speed is a large factor in the pain, risk and stupidity function, i.e. the more over the limit you are, the more stupid you are being.

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I stole this .sig

As you pointed out, there's no relationship between deltaV and free travelling speed.
Additionally, whereas an overweight lorry always results in a quantifiable amount of excessive damage to the roads, the 4th power relationship between deltaV and fatality risk only exists in the rare event of an actual collision.

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Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

You're a veteran of 2,000 posts on these forums, and you still think it's stupid to break the law? Despite the fact that the most intelligent people in the land do it?

And especially when there's a far more important and intelligent way to adjust speed - speed must be adjusted to the road conditions and the hazard environment. Given that, it's stupid to place significant value in mere legal compliance when lives are at stake.

I thought you were going to stop trolling and start debating honestly, but it seems I was wrong.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

You are wrong about everything, mate, but it is your use of misleading jargon and trashy ad hominem that is disgustingly wrong. The question you should ask is “does free travelling speed have a non-trivial effect on the outcome?”

And it does – because it profoundly affects the likelihood of a crash happening in the first place (as you have often conceded), and higher speeds have a worse effect than lower ones.

I have no problem with your obsessive-compulsive disorder, as long as you keep it off the roads. So far, you claim you have not been fined, so I can only assume you are being a good boy, or you have been lucky up to now.

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I stole this .sig