Safespeed spoilsports

[Paul Smith]

On Tue, 04 Mar 2003 09:19:32 +0000, "Just zis Guy, you know?" <[email protected]> wrote:

>>>with 30% less KE to start with, the chances of the crash actually happening in the first place
>>>are dramatically reduced. Assuming the drive can dump enough KE to slow from 80 to an impact
>>>speed of below 39mph, if he'd been doing 70 he would have stopped short of the other vehicle, all
>>>other things being equal (the difference in KE between 80mph and 39mph being the same as that
>>>between 70 and 0).

>>>Seems simple enough - I don't think anybody else missed it.

>>I didn't miss it. I consider it simplistic and misleading.

>ROTFLMAO! Physics is simplistic and misleading, while misapplying a rule of thumb out of context to
>speeds below it's useful cutoff point is "illuminating!" You really are priceless!

If you can't see beyond the basics, that's not my problem.

>>I can't imaging why you want to concentrate on a small contributor to average crash energy.

>I was actually focussing on a major contributor to crash energy - the fact that a car exceeding the
>motorway limit by as little as 10mph has 30% more KE to shed in order to avoid a crash in the first
>place, making it correspondingly less likely that they will succeed.

What evidence have you got that pre-incident KE is a big contributor to average crash energy? I'll
give you a clue. There isn't any.

And this has nothing to do with speed limits. It'll be true with any speed limit and any degree of
enforcement.
--
Paul Smith Scotland, UK http://www.safespeed.org.uk please remove "XYZ" to reply by email speed
cameras cost lives

 

[Paul Smith]

On Tue, 4 Mar 2003 09:46:18 -0000, "Tony W" <[email protected]> wrote:

>> I can't imaging why you want to concentrate on a small contributor to average crash energy.

>Maybe because the bit that is left is the bit that kills people.

That's not good enough. If driver response on average reduces crash CE by well over 95%, we should
be looking to improve that, rather than the < 5% contribution from pre-incident CE.
--
Paul Smith Scotland, UK http://www.safespeed.org.uk please remove "XYZ" to reply by email speed
cameras cost lives

 

[Paul Smith]

On 04 Mar 2003 10:13:20 +0000, Alan Braggins <[email protected]> wrote:

>> >> How are YOU going to slow US down without risking altering our responses?

>> >If you aren't capable of slowing yourself down, by jailing you for driving while disquailified,
>> >ultimately.

>> Suppose we use threats to slow everyone down to exactly the speed
>> limit. Everyone drives with one eye on the speedo in case some invisible police robot catches
>> them.

>Then they will ultimately be disqualified for driving without due care and attention, not for
>speeding. Most of us are capable of keeping a roughly constant speed without more than an
>occasional glance at the speedo. If it's necessary to meet your strawman condition that the speed
>never exceeds the limit by even a tiny bit, you can simply make the average a fraction below the
>limit instead of sticking religiously exactly to it. "A limit, not a target", remember?

Speed limits are fine.

Distracting drivers and making them paranoid is criminal.
--
Paul Smith Scotland, UK http://www.safespeed.org.uk please remove "XYZ" to reply by email speed
cameras cost lives

 

[Paul Smith]

On Tue, 4 Mar 2003 10:46:39 -0000, "Tony W" <[email protected]> wrote:

>> Accident situations develop. Sometimes you might find a contributory factor five seconds before
>> the "first error". Just open your mind to the possibility of looking more widely and learning
>> more. You're compartmentalising, and it isn't a safe approach to accident understanding.

>You clearly have no understanding of modelling techniques.

I don't have any problem with modelling, so long as all the factors are properly considered.

But far too many hypothetical accidents start too late. That's my main point.
--
Paul Smith Scotland, UK http://www.safespeed.org.uk please remove "XYZ" to reply by email speed
cameras cost lives

 

[Peter Amey]

[snip]
>
> What evidence have you got that pre-incident KE is a big contributor to average crash energy? I'll
> give you a clue. There isn't any.
>
> And this has nothing to do with speed limits. It'll be true with any speed limit and any degree of
> enforcement.

I may not have your grasp of physics and statistics but I think I would be prepared to wager that a
pre-incident KE of 0 would greatly reduce the likelihood of an accident and the severity of any that
occurred. This precondition could be achieved with a speed limit of 0 and 100% enforcement. Your
statement is therefore false.

Peter

 

[Just Zis Guy]

On Tue, 04 Mar 2003 11:02:16 +0000, Paul Smith <[email protected]> wrote:

>>>All these imaginary accidents that get bandied about... "suddenly someone steps into the road...
>>>he only has 100 feet to stop in ... if he had been going 5 mph slower he could have stopped"
>>>rubbish.

>>Those would be the imaginary accidents which account for the 9,000 pedestrians KSI.

>No. I was talking about hypothetical accidents. As you very well know.

Is that the same as the hypothetical accidents caused by speed cameras which you're always
banging on about?

>You're just being stupid.

Apologies for violating your trademark. I won't do it again.

 

[Paul Smith]

On Tue, 04 Mar 2003 12:01:47 +0000, Peter Amey <[email protected]> wrote:

>> What evidence have you got that pre-incident KE is a big contributor to average crash energy?
>> I'll give you a clue. There isn't any.

>> And this has nothing to do with speed limits. It'll be true with any speed limit and any degree
>> of enforcement.

>I may not have your grasp of physics and statistics but I think I would be prepared to wager that a
>pre-incident KE of 0 would greatly reduce the likelihood of an accident and the severity of any
>that occurred. This precondition could be achieved with a speed limit of 0 and 100% enforcement.
>Your statement is therefore false.

Ok then, ... with any practical speed limit and any practical degree of enforcement.

But I'm sure you would have been able to safely assume I meant "within reason".
--
Paul Smith Scotland, UK http://www.safespeed.org.uk please remove "XYZ" to reply by email speed
cameras cost lives

 

[Just Zis Guy]

On Tue, 04 Mar 2003 11:11:15 +0000, Paul Smith <[email protected]> wrote:

>If you can't see beyond the basics, that's not my problem.

I long for the day when you get as far as seeing the basics.

>>I was actually focussing on a major contributor to crash energy - the fact that a car exceeding
>>the motorway limit by as little as 10mph has 30% more KE to shed in order to avoid a crash in the
>>first place, making it correspondingly less likely that they will succeed.

>What evidence have you got that pre-incident KE is a big contributor to average crash energy? I'll
>give you a clue. There isn't any.

Well now, let me see. There are two main mechanisms by which pre-incident KE contributes to crash
nergy, and they are these:

First, the crash energy is formed of a component of pre-incident KE. Therefore, the pre-incident KE
contributes in the same way that a cow contributes to a steak. This much is obvious.

Second, if the pre-incident KE is, say, for the sake of illustration, 30% lower by virtue of the car
going at 70mph instead of 80mph THE CRASH MAY NOT HAPPEN AT ALL. This much is also obvious.

Work it any way you want. Start at the crash and work back, the car at 70mph can brake at the same
time but less sharply reducing the chances of loss of control or being shunted by the tailgater
behind, the driver can brake at the same tiome with the same force and avoid the accident, or the
driver has a brief extra margin for error in his attention and can still reduce to the same speed at
the same point. Start at the point the driver sees the incident and work forward, if both cars dump
the same amount of KE the 80mph car is stilldoing nearly 40mph when the 70mph car stops. And this,
too, is obvious.

>And this has nothing to do with speed limits. It'll be true with any speed limit and any degree of
>enforcement.

In every circumstance, on every road, in every case, in every car, with every driver, if the vehicle
were going slower the chances of fatal injury in a given circumstance must reduce. That's the laws
of physics for you. So exceeding the speed limit is by definition bringing more danger to the
situation. That's what it has to do with speed limits. This is also obvious.

 

[Just Zis Guy]

On Tue, 04 Mar 2003 11:15:13 +0000, Paul Smith <[email protected]> wrote:

>Speed limits are fine. Distracting drivers and making them paranoid is criminal.

Obvious conclusion: since speed limits have always existed and always been enforced to some extent,
those drivers who allow themselves to become so focussed on speed as to allow it to take first place
over safety are dangerous drivers.

Remember: even learners are supposed to be able to drive within the speed limit.

 

[Paul Smith]

On Tue, 04 Mar 2003 12:50:19 +0000, "Just zis Guy, you know?" <[email protected]> wrote:

>>What evidence have you got that pre-incident KE is a big contributor to average crash energy? I'll
>>give you a clue. There isn't any.

>Well now, let me see. There are two main mechanisms by which pre-incident KE contributes to crash
>nergy, and they are these:

>First, the crash energy is formed of a component of pre-incident KE. Therefore, the pre-incident KE
>contributes in the same way that a cow contributes to a steak. This much is obvious.

>Second, if the pre-incident KE is, say, for the sake of illustration, 30% lower by virtue of the
>car going at 70mph instead of 80mph THE CRASH MAY NOT HAPPEN AT ALL. This much is also obvious.

>Work it any way you want. Start at the crash and work back, the car at 70mph can brake at the same
>time but less sharply reducing the chances of loss of control or being shunted by the tailgater
>behind, the driver can brake at the same tiome with the same force and avoid the accident, or the
>driver has a brief extra margin for error in his attention and can still reduce to the same speed
>at the same point. Start at the point the driver sees the incident and work forward, if both cars
>dump the same amount of KE the 80mph car is stilldoing nearly 40mph when the 70mph car stops. And
>this, too, is obvious.

All that dancing around, and you haven't even considered the specific question. Is this supposed to
be distraction?

>>And this has nothing to do with speed limits. It'll be true with any speed limit and any degree of
>>enforcement.

>In every circumstance, on every road, in every case, in every car, with every driver, if the
>vehicle were going slower the chances of fatal injury in a given circumstance must reduce. That's
>the laws of physics for you. So exceeding the speed limit is by definition bringing more danger to
>the situation. That's what it has to do with speed limits. This is also obvious.

But you can't make a vehicle slower without changing the circumstances. So that's *completely*
meaningless.
--
Paul Smith Scotland, UK http://www.safespeed.org.uk please remove "XYZ" to reply by email speed
cameras cost lives

 

[Paul Smith]

On Tue, 4 Mar 2003 12:54:02 -0000, "Tony W" <[email protected]> wrote:

>> >Maybe because the bit that is left is the bit that kills people.

>> That's not good enough. If driver response on average reduces crash CE by well over 95%, we
>> should be looking to improve that, rather than the < 5% contribution from pre-incident CE.

>Why not consider

>1. Reduced speed at start of incident.

If available, then fine, but we have to be realistic about side effects. See:

http://www.safespeed.org.uk/tiger.html

>2. Better hazard awareness before the incident

Yes please.

>3. Improved response after the initiation of the incident

Yes please.

>as three valid, mutually supporting, methods of avoiding death or serious injury.

I don't believe in that "supporting" part as things are on UK roads.

>Why do you continuously ignore 1 and only harp on about 2 and 3?

Your number 1) as interpreted by the authorities at the present time, is actually reducing drivers'
performances at 2 and 3.

>1 is the easiest to implement. 2 & 3 require experience, possibly additional training and improved
>technology.

>Open your mind to the possibility that faster is not always best.

Faster is sometimes extremely dangerous. Speed should always be used safely. Asking drivers to
stick rigidly to speed limits does not accomplish this. Canadian research put 2/3rds of excess
speed accidents as taking place within the speed limit. It's reasonable to expect that the same
applies on UK roads.

I'd be very happy with a campaign which focussed on "always being able to stop within the distance
you know to be clear". That would address 100% of excess speed accidents. What we're now doing is
addressing one third of excess speed accidents badly, and distracting drivers at the same time. And
we've even let the traffic police move to other duties to compound the error.
--
Paul Smith Scotland, UK http://www.safespeed.org.uk please remove "XYZ" to reply by email speed
cameras cost lives

 

[Paul Smith]

On Tue, 04 Mar 2003 12:52:58 +0000, "Just zis Guy, you know?" <[email protected]> wrote:

>>Speed limits are fine. Distracting drivers and making them paranoid is criminal.

>Obvious conclusion: since speed limits have always existed and always been enforced to some extent,
>those drivers who allow themselves to become so focussed on speed as to allow it to take first
>place over safety are dangerous drivers.

Speed limit enforcement was just right until about 1990. Then the silly season started.

On the dangerous driver point, I expect about 60% of drivers are dangerous by your definition, and
it's quite possible that 99% have "dangerous moments" by the same definition.

You can't base a road safety strategy on idealised drivers. You have to base it on what we've got.
--
Paul Smith Scotland, UK http://www.safespeed.org.uk please remove "XYZ" to reply by email speed
cameras cost lives

 

[Tony W]

"Paul Smith" <[email protected]> wrote in message
news:[email protected]...

> >Maybe because the bit that is left is the bit that kills people.
>
> That's not good enough. If driver response on average reduces crash CE by well over 95%, we should
> be looking to improve that, rather than the < 5% contribution from pre-incident CE.

Ahhhhhhggggggggghhhhhh!

Why not consider

1. Reduced speed at start of incident.

2. Better hazard awareness before the incident

3. Improved response after the initiation of the incident

as three valid, mutually supporting, methods of avoiding death or serious injury.

Why do you continuously ignore 1 and only harp on about 2 and 3?

1 is the easiest to implement. 2 & 3 require experience, possibly additional training and improved
technology.

Open your mind to the possibility that faster is not always best.

T

 

[Just Zis Guy]

On Tue, 04 Mar 2003 13:03:58 +0000, Paul Smith <[email protected]> wrote:

>All that dancing around, and you haven't even considered the specific question. Is this supposed to
>be distraction?

All that dancing around and you still haven't considered the laws of physics. Are you supposed to
be credible?

>>In every circumstance, on every road, in every case, in every car, with every driver, if the
>>vehicle were going slower the chances of fatal injury in a given circumstance must reduce. That's
>>the laws of physics for you. So exceeding the speed limit is by definition bringing more danger to
>>the situation. That's what it has to do with speed limits. This is also obvious.

>But you can't make a vehicle slower without changing the circumstances. So that's *completely*
>meaningless.

What you have done is take figures which show that the probability of death increases with the
fourth power of speed, and inverted them to "prove" that initial speed plays no part in the
probability of fatality. There are so many discontinuities in your reasoning that it's hard to take
it seriously at all, and I don't think any of us would bother if it weren't for the fact that you
appear to believe that saying it makes it true. This started as a dicussion of the 12mph comedy web
page, which you have now taken down following comments from Joksch which told you what you had
already been told several times by others around here - that your use of his rule of thumb was
invalid, and the application of it was invalid in context.

You now appear to be trying to argue that in considering crash energy we must ignore the fact that
KE increases with the square of speed, and assume that those who are driving at 70mph will
*necessarily* react less quickly than those who are driving at 80mph, which is the only conceivable
way that an impact can still happen at a given speed. I take issue with this. At least one
highly-regarded road safety advocate tells me that I can be safe and still obey the speed limit. And
this is quite believable - I was required to demonstrate that I could do so before being allowed to
drive unaccompanied, after all.

 

[Just Zis Guy]

On Tue, 04 Mar 2003 13:14:58 +0000, Paul Smith <[email protected]> wrote:

>If available, then fine, but we have to be realistic about side effects. See:
>http://www.safespeed.org.uk/tiger.html

There is a widely held belief that drivers can be exoected to drive safely within the speed limit,
and some are so rash as to suggest that having been required to demonstrate this at the time of
passing their driving test it is not unreasonable to suppose that they may continue to be required
to do so without significant detriment to road safety as they become more experienced. Funny, that.

>Your number 1) as interpreted by the authorities at the present time, is actually reducing drivers'
>performances at 2 and 3.

Oops! Argument by assertion again. Where's the proof? Oh, yes, you have acknowledged you don't have
any of course. Ah, well.

>Canadian research put 2/3rds of excess speed accidents as taking place within the speed limit. It's
>reasonable to expect that the same applies on UK roads.

And equally reasonable to suggest that this is not an argument for not enforcing speed limits.

>speed cameras cost lives

But only when combined with dangerous drivers who are prepared to put speed above safety. Obviously.

 

[Just Zis Guy]

On Tue, 04 Mar 2003 13:18:53 +0000, Paul Smith <[email protected]> wrote:

>You can't base a road safety strategy on idealised drivers. You have to base it on what we've got.

And allowing the current dangerous drivers to continue flagrantly disobeying whatever parts of the
law they find momentarily inconvenient is not the very best approach.

 

[Alan Braggins]

Paul Smith <[email protected]> writes:
> On Tue, 04 Mar 2003 12:52:58 +0000, "Just zis Guy, you know?" <[email protected]> wrote:
> >Obvious conclusion: since speed limits have always existed and always been enforced to some
> >extent, those drivers who allow themselves to become so focussed on speed as to allow it to take
> >first place over safety are dangerous drivers.
[...]
> On the dangerous driver point, I expect about 60% of drivers are dangerous by your definition

You claim 99% of drivers exceed the speed limit, most of them safely, but now you claim 60% of them
are so focussed on sticking to the speed limit that they put it above safety. What's wrong with
this picture?

 

[Ambrose Nankive]

Just zis Guy, you know? wrote:
> I take issue with this. At least one highly-regarded road safety advocate tells me that I can be
> safe and still obey the speed limit. And this is quite believable - I was required to demonstrate
> that I could do so before being allowed to drive unaccompanied, after all.

I take issue with this. I (inadvertantly) broke the speed limit during my driving test and still
managed to pass. Of course, it's more likely that the examiner didn't notice it as it was on a wide
road (less sensation of speed, as any traffic planner who's put cycle lanes in to slow the motor
traffic down), and on a downhill (so the engine noise wasn't noticeable).

What's more, Paul Smith does have a point that low speeds can cause frustration and that frustration
can cause collisions. Mainly because impatient hotheads lose their temper and drive into things or
get out and hit people.

However, I imagine that in most places the speed limits are sufficiently high to avoid this
happening so this effect can be safely discounted. I'd be interested to know if this is the
rationale behind Paul Smith's claim that driver ability increases with speed.

Furthermore, I'm not a hugely experienced driver, but I find that at speeds well within the speed
limit, my senses are well saturated with inputs and potential hazards, perhaps with the exception of
empty motorways.

Ambrose

 

[Tim Woodall]

On Tue, 04 Mar 2003 15:05:17 +0000, Just zis Guy, you know? <[email protected]> wrote:
> On Tue, 04 Mar 2003 13:14:58 +0000, Paul Smith <[email protected]> wrote:
>
>>If available, then fine, but we have to be realistic about side effects. See:
>>http://www.safespeed.org.uk/tiger.html
>
> There is a widely held belief that drivers can be exoected to drive safely within the speed limit,
> and some are so rash as to suggest that
It took me a while to work this one out. No excuse either Guy, it's your right hand ;-)

But yes, I'm pretty sure if we started mounting exocets on the top of speed cameras then people
might stop speeding.

Tim.

--
God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J + @D/@t," and there was light.

http://tjw.hn.org/ http://www.locofungus.btinternet.co.uk/

 

[Paul Smith]

On Tue, 4 Mar 2003 15:24:57 -0000, "Ambrose Nankivell" <[email protected]> wrote:

>What's more, Paul Smith does have a point that low speeds can cause frustration and that
>frustration can cause collisions. Mainly because impatient hotheads lose their temper and drive
>into things or get out and hit people.

>However, I imagine that in most places the speed limits are sufficiently high to avoid this
>happening so this effect can be safely discounted. I'd be interested to know if this is the
>rationale behind Paul Smith's claim that driver ability increases with speed.

I do not claim that driver ability increases with speed. (Although on occasions it is possible.) I'm
much more concerned that present speed enforcement alters drivers' priorities to include a task high
on the list which actually has a very small safety benefit. See this web page:

http://www.safespeed.org.uk/tiger.html

>Furthermore, I'm not a hugely experienced driver, but I find that at speeds well within the speed
>limit, my senses are well saturated with inputs and potential hazards, perhaps with the exception
>of empty motorways.

This should happen to every driver from time to time. Of course the correct response is to slow down
immediately. With more experience, one tends to be able to slow down well before it happens.
--
Paul Smith Scotland, UK http://www.safespeed.org.uk please remove "XYZ" to reply by email speed
cameras cost lives