From: Steve Firth on
JMS <jmsmith2010(a)live.co.uk> wrote:

> >I work in a large medical school.
>
>
> No you don't.

It's probable that he does some work in a medical school. However he's
an IT officer. That means that his opinion on cranial trauma is worth as
much as that of any similar individual at that school.

For the avoidance of doubt, "similar" in this context refers to any
another non-medically qualified staff such as cleaners, porters, kitchen
assistants, groundskeepers, accounts clerks, carpenters, handymen etc.

Quite why an IT droid working in an organisation that is notable for its
IT fuckups should try to equate their knowledge to that of an
experienced surgeon is one that Mr Clinch will no doubt be in a hurry to
explain. Mr Clinch may well be that pearl among IT support staff who
ourreach the capabilities of their peers, but so far he's provided no
evidence of that. And even if he manages it, it's still not going to to
raise his competence to comment on medical matters above that of his
fellow tradesmen.

From: Adrian on
Tony Raven <traven(a)gotadsl.co.uk> gurgled happily, sounding much like they
were saying:

>> I've yet to see any figures to suggest how many KSIs are due to people
>> driving with BAC between 50 & 80.

> There is good evidence from the US

Wake me up when the US start to take drink-driving seriously enough to
routinely test in a more sensible way than the "roadside sobriety test",
and to punish with more than a minor slap on the wrist.
From: Tony Raven on
Adrian wrote:
> Tony Raven <traven(a)gotadsl.co.uk> gurgled happily, sounding much like they
> were saying:
>
>>> I've yet to see any figures to suggest how many KSIs are due to people
>>> driving with BAC between 50 & 80.
>
>> There is good evidence from the US
>
> Wake me up when the US start to take drink-driving seriously enough to
> routinely test in a more sensible way than the "roadside sobriety test",
> and to punish with more than a minor slap on the wrist.

Wakey wakey!!! The FST (Field Screening Test) increasingly uses
breathalysers (PAS - Preliminary Alcohol Screening - or PBT -
Preliminary Breath Test) these days. Anyone failing the screening test
is then taken back to the police station for a proper blood, breath or
urine alcohol test.
http://www.dmv.ca.gov/pubs/vctop/d06/vc13388.htm

Penalties tend to be bipolar - light if nothing much happened, heavy if
someone was injured.

--
Tony

" I would never die for my beliefs because I might be wrong."
Bertrand Russell
From: Sniper on
None of which would alter the basic premise of my general statement...

Had the forces involved been sufficient to cause a skull fracture then
those forces would undoubtedly have caused a complete failure of the
cycle helmet.. this being a certainty given the structural failure
requirements of cycle helmets.

If as you state the helmet did not fail then it is also proven that the
forces involved were insufficient to cause significant head trauma: by
which I mean a fracture to the skull.

Ergo: the helmet did not mediate the danger of a fractured skull but may
have reduced the incidence of minor facial and dermatological injury.

FYI compression fracture resistance of the human skull is 170 MPa
(Cameron, et al.) or 24656.41 psi.

A cycle helmet produced to the current standard (EN 1078:1997)(BS EN
1078:1997) is designed to mitigate impacts by decelerating the human
brain within a deformable shell e.g. polystyrene foam. In order to keep
deceleration below 300g this representing the maximum deceleration that
can be applied to the human head without causing brain injury the
deformability of the foam insert cannot rise above 0.9MPa or 130.53 psi.

If one allows that an impact had the potential to cause death by
compression fracture the spent energy absorbed by the wearing of a
helmet(assuming it did not fail)could be no more than 130.5 psi leaving
some 24525.88 psi to be dissipated by the skull before a compression
fracture is likely to occur.

The question one might then legitimately ask is: is there any likelihood
that an absorption potential of 130.5 psi will make any significant
contribution to the saving of a life where the impact force required to
cause a fracture so far exceeds the capability of the helmet structure
to mitigate that force?

I would suggest it is highly unlikely.

One might also argue that a fractured skull in itself does not
necessarily result in death so that even in an unprotected head the
likelihood of brain injury is not a certainty provided that the
deceleration applied does not rise above 300g. Particularly if one
notes the human skull will distribute forces below the fracture
potential load over the surface area of the skull where as the cycle
helmet will not as it must by design fail at 130.53 psi.


Sniper.

On 22/05/2010 12:39, Derek C wrote:
> On 22 May, 12:06, Sniper<Sniper8...(a)yahoo.co.uk> wrote:
>> The best that can be said of cycle helmets is they may save some minor
>> injury...
>>
>> The worst that can be said of cycle helmets is that they may cause some
>> avoidable fatalities...
>>
>> The assertion that a cycle helmet may or will save your life is
>> undoubtedly a fallacy based in poor understanding of basic principles of
>> physics and engineering.
>>
>> A cycle helmet, when smashed to bits, is frequently described as 'having
>> absorbed the impact' or having 'done its job' Whereas in truth it has
>> simply failed... it failed to absorb any impact as the load applied
>> exceeded its capability to transfer that load across its surface hence
>> it failed.
>>
>> A motorcycle helmet exhibiting a similar result would not be passed as
>> fit for sale... in a collision, even with a head on impact a motorcycle
>> helmet is expected not to fail e.g. be reduced to a broken shell.
>>
>> Ergo: a cycle helmet in pieces has failed...
>>
>> Ergo: a cycle helmet that will not transfer loads without failure above
>> the fracture frequency load currently in use is unlikely to save one's
>> life in a cycle/motor vehicle collision: it may dissipate a bump to the
>> head and save minor injury in a 'non direct impact' fall, e.g. where
>> impact of the head is secondary: but, where the forces involved are
>> sufficient to cause death in a non helmet wearing cyclist then the
>> wearing of a cycle helmet will not alter that outcome until cycle
>> helmets are sufficiently strong enough to withstand the forces applied
>> to them during 'direct impact - fatal load' collisions... at which point
>> a new series of fatality questions might possibly be presented.
>>
>> Going back to my law degree I leave you to your musings...
>>
>> Sniper:
>
> The helmet in the example given had not split or failed in any way. It
> was slightly dented at the front and some bits of foam had been gouged
> out to the depth of a few millmetres, presumable as a result of
> hitting a paved or tarmaced surface. Cycle helmets are essentially one
> shot devices that should be thrown away after any significant impacts.
> Actually they are two shot to absorb initial and secondary impacts.
>
> Motor cycle helmets would be much too heavy and poorly ventilated for
> cycling use, and also impair your hearing which is a good defence
> mechanism for cyclists who can hear vehicles coming (except for
> electric hybrids). Heavy helmets increase the risk of a neck injury in
> high g decelerations, which is why racing drivers wear those helmet
> restraint devices on their shoulders.
>
> Derek C

From: JMS jmsmith2010 on
On Fri, 21 May 2010 15:28:26 +0100, Peter Clinch
<p.j.clinch(a)dundee.ac.uk> wrote:

<snip>


>AFAICT Accident Analysis and Prevention is actually a peer reviewed
>journal, so presumably the contents of vol. 39, pages 417-425 are peer
>reviewed?
>
>Pete.


OK Walker managed to get it published somewhere - was it one of the
journals where you have to pay?

It would indeed be interesting to see who peer reviewed it: I wonder
if they get paid for doing so?

I wonder if he corrected his mis-use of axes which gave a distorted
view of his results.

Whilst you have to pay to see the pages to which Clinch refers - here
is a review which is free:

=============================================================================
A study published in the March 2007 issue of Accident Analysis &
Prevention showed that drivers drove an average of 8.5 cm closer, and
came within 1 meter 23% more often, when a cyclist was wearing a
helmet.[2]

However, it should be noted that this paper is considered by many as a
source of ridicule. For example it seriously states:

"The closer a driver is to the cyclist, the greater chance of a
collision."
"Drivers passed closer to the rider the further out into the road he
was."

There have been a number of critical articles about this piece of
research and its "biased" presentation, including the fact that Dr
Walker chose to present his results graphically with a non-zero origin
for his axis showing Main Overtaking Proximity which gives a false
representation of the results. There is a critical review in the
paper "Further Research Inspired by Dr. Ian Walker's, Drivers
overtaking bicyclists". (The fact that this article was dated 1 April
is not thought to be significant).

It has been said that Dr Walker had a particular result in mind - and
his research was carried out specifically to prove a point. It has
now been shown that he failed.


http://www.outthereliving.com/Ian_Walker_move_over_pls.pdf



--
Many cyclists are proving the need for registration by their contempt for the Highway Code and laws.

The answer:
All cyclists over 16 to take compulsory test, have compulsory insurance, and be registered.
Registration number to be clearly visible on the back of mandatory hi-viz vest.
Habitual law breakers' cycles confiscated and crushed.
(With thanks to KeithT for the idea)