A helmet saved my life -- believe it



A

Ambrose Nankivell

Guest
Howard wrote:
> (Although
> such a test would tell us very little about it's ability to absorb the
> energy of an impact, and of course the main problem in an impact is
> the fact that nothing can prevent the brain from 'sloshing' around
> inside the skull, being torn, lacertated, contused and otherwise
> damaged as it does so).
>

Really? Nothing can prevent that?

My head is permanently covered in a slip promoting material, which I
believe is there to deflect the head away from impacts where it is
avoidable.

Well, looking at my dad, it's possible that it'll be gone within twenty
years, so maybe permanent's the wrong word.

A
 
B

burt

Guest
"Marc Brett" <[email protected]> wrote in message
news:[email protected]
>
> For all you doubting-Thomases who think helmets don't work in real-world
> collisions with vehicles.
>
>
> Bike helmet crushed, but head fine
> http://www.madison.com/tct/news/index.php?ntid=133934
>


Just posted the response below:

"Burtthebike says:

This story is complete, total, utter nonsense.


It may be true that the cyclist and the truck were in collision, but to
claim that the cycle helmet saved his life after the truck ran over his head
merely demonstrates that the cyclist was most definitely suffering from
concussion. No cycle helmet will protect your head if you get run over by a
relatively small car, let alone a truck! Hogwash dressed up to sell helmets
and make the cyclist feel good.


We've only got his word for it that it ran over his head, and given that
that is impossible, the rest of his story must be open to question. As one
of the other posters asked, where are the witnesses and why did no-one get
the licence plate?


Urban myth in the making. Believe this and demonstrate your gullibility and
lack of independent thought."
 
I

Ingo Keck

Guest
I wrote:

[... sobre http://www.madison.com/tct/news/index.php?ntid=133934 ...]

> I agree with you and I put a similar comment on the same page maybe six
> hours ago. Shortly afterwards there were more comments on the same
> subject.
>
> Now (18:02 in Barcelona) all these comments (including mine) have
> disappeared.
>
> I have sent an email to [email protected], lets see what has
> happend.


The comments were "thought to be SPAM" and deleted. The guy behind it
apologized and asked me to repost.

Really funny. :-(

Ingo.
 
T

Tony Raven

Guest
Clive George wrote on 15/05/2007 13:17 +0100:
>
> (* you can substitute a full bean can if you want - that'll take a much
> bigger force, with the contents providing the strength, provided you can
> promise the squishy bits inside the skull don't have anywhere to go...)
>


You never saw the pictures in my school text books then of a double
decker bus standing on four unbroken bone china cups?

--
Tony

"The most savage controversies are those about matters as to which there
is no good evidence either way."
- Bertrand Russell
 
C

Clive George

Guest
"Tony Raven" <[email protected]> wrote in message
news:[email protected]
> Clive George wrote on 15/05/2007 13:17 +0100:
>>
>> (* you can substitute a full bean can if you want - that'll take a much
>> bigger force, with the contents providing the strength, provided you can
>> promise the squishy bits inside the skull don't have anywhere to go...)
>>

>
> You never saw the pictures in my school text books then of a double decker
> bus standing on four unbroken bone china cups?


Go on then - what static load do you reckon the skull can take sideways? And
what load if it arrives in a careless fashion, as a lorry wheel is wont to
do?

cheers,
clive
 
T

Tony Raven

Guest
Clive George wrote on 15/05/2007 19:19 +0100:
>
> Go on then - what static load do you reckon the skull can take sideways?
> And what load if it arrives in a careless fashion, as a lorry wheel is
> wont to do?
>


I don't know but I will go and find out..........
[time passes]
......5,000 - 31,000psi in static compression.
Leestma J.E., Forensic Neuropathology, Raven Press, New York, 1988,
Chapter 4


--
Tony

"The most savage controversies are those about matters as to which there
is no good evidence either way."
- Bertrand Russell
 
C

Chris Eilbeck

Guest
Marc Brett <[email protected]> writes:

> For all you doubting-Thomases who think helmets don't work in real-world
> collisions with vehicles.
>
>
> Bike helmet crushed, but head fine
> http://www.madison.com/tct/news/index.php?ntid=133934
>
> A white paneled delivery truck ran over a UW-Madison graduate
> student's head on Division Street Friday afternoon and, except for a
> concussion, he wasn't hurt.


Now go and repeat the experiment without the helmet.

Chris
--
Chris Eilbeck
 
C

Clive George

Guest
"Tony Raven" <[email protected]> wrote in message
news:[email protected]
> Clive George wrote on 15/05/2007 19:19 +0100:
>>
>> Go on then - what static load do you reckon the skull can take sideways?
>> And what load if it arrives in a careless fashion, as a lorry wheel is
>> wont to do?
>>

>
> I don't know but I will go and find out..........
> [time passes]
> .....5,000 - 31,000psi in static compression.
> Leestma J.E., Forensic Neuropathology, Raven Press, New York, 1988,
> Chapter 4


That doesn't actually answer my question - what total sideways crushing
load? Point pressure is rather different.

If I take four people with their heads placed sideways, would they be able
to hold up that double decker bus you mentioned in the same way as the cups?
I'm guessing not, because the stress isn't compressive in the middle. If the
sides of the skull are supported, maybe, but without that won't they just
fold?

cheers,
clive
 
T

Tony Raven

Guest
Clive George wrote on 15/05/2007 19:47 +0100:
> "Tony Raven" <[email protected]> wrote in message
> news:[email protected]
>> Clive George wrote on 15/05/2007 19:19 +0100:
>>>
>>> Go on then - what static load do you reckon the skull can take
>>> sideways? And what load if it arrives in a careless fashion, as a
>>> lorry wheel is wont to do?
>>>

>>
>> I don't know but I will go and find out..........
>> [time passes]
>> .....5,000 - 31,000psi in static compression.
>> Leestma J.E., Forensic Neuropathology, Raven Press, New York, 1988,
>> Chapter 4

>
> That doesn't actually answer my question - what total sideways crushing
> load? Point pressure is rather different.


No that is area not point pressure.

>
> If I take four people with their heads placed sideways, would they be
> able to hold up that double decker bus you mentioned in the same way as
> the cups? I'm guessing not, because the stress isn't compressive in the
> middle. If the sides of the skull are supported, maybe, but without that
> won't they just fold?
>


It almost certainly will. Take the example of free divers. They have
set a record so far of 150m depth. The water pressure at that depth is
15 atmospheres or 225psi. Given the dimensions of the head that is
equivalent to a static loading of about ten tons on one side of the
head. I am not aware of there being any concerns about their skulls
being crushed at those loadings. The human skull is remarkably strong.


--
Tony

"The most savage controversies are those about matters as to which there
is no good evidence either way."
- Bertrand Russell
 
H

Howard

Guest
On May 15, 8:08 pm, Tony Raven <[email protected]> wrote:

>
> > If I take four people with their heads placed sideways, would they be
> > able to hold up that double decker bus you mentioned in the same way as
> > the cups? I'm guessing not, because the stress isn't compressive in the
> > middle. If the sides of the skull are supported, maybe, but without that
> > won't they just fold?

>
> It almost certainly will. Take the example of free divers. They have
> set a record so far of 150m depth. The water pressure at that depth is
> 15 atmospheres or 225psi. Given the dimensions of the head that is
> equivalent to a static loading of about ten tons on one side of the
> head. I am not aware of there being any concerns about their skulls
> being crushed at those loadings. The human skull is remarkably strong.
>


Similarly, does anyone else recall the 70's kids program 'How' where
they got Fred Dinage to stand on 4 eggs held in an upright frame, and
they withstood his weight?
 
C

Clive George

Guest
"Tony Raven" <[email protected]> wrote in message
news:p[email protected]
> Clive George wrote on 15/05/2007 19:47 +0100:
>> "Tony Raven" <[email protected]> wrote in message
>> news:[email protected]
>>> Clive George wrote on 15/05/2007 19:19 +0100:
>>>>
>>>> Go on then - what static load do you reckon the skull can take
>>>> sideways? And what load if it arrives in a careless fashion, as a lorry
>>>> wheel is wont to do?
>>>>
>>>
>>> I don't know but I will go and find out..........
>>> [time passes]
>>> .....5,000 - 31,000psi in static compression.
>>> Leestma J.E., Forensic Neuropathology, Raven Press, New York, 1988,
>>> Chapter 4

>>
>> That doesn't actually answer my question - what total sideways crushing
>> load? Point pressure is rather different.

>
> No that is area not point pressure.


What area, and where?

>> If I take four people with their heads placed sideways, would they be
>> able to hold up that double decker bus you mentioned in the same way as
>> the cups? I'm guessing not, because the stress isn't compressive in the
>> middle. If the sides of the skull are supported, maybe, but without that
>> won't they just fold?
>>

>
> It almost certainly will. Take the example of free divers. They have set
> a record so far of 150m depth. The water pressure at that depth is 15
> atmospheres or 225psi. Given the dimensions of the head that is
> equivalent to a static loading of about ten tons on one side of the head.
> I am not aware of there being any concerns about their skulls being
> crushed at those loadings. The human skull is remarkably strong.


It's not equivalent at all. That's a pressure which is applied all round the
skull, not a sideways crushing force such as one would get from clamping it
in a vice or having a lorry standing on the side of your head.

Consider your china cup example - would they be able to take the same load
lying on their side? No, of course not.

Yes, the skull is remarkably strong. But the load I'm talking about isn't
one it would have evolved to take.

cheers,
clive
 
N

Nigel Randell

Guest
Howard wrote:
> On May 15, 9:57 am, Marc Brett <[email protected]> wrote:
>> For all you doubting-Thomases who think helmets don't work in
>> real-world
>> collisions with vehicles.
>>
>> Bike helmet crushed, but head
>> finehttp://www.madison.com/tct/news/index.php?ntid=133934
>>
>> A white paneled delivery truck ran over a UW-Madison graduate
>> student's
>> head on Division Street Friday afternoon and, except for a
>> concussion,
>> he wasn't hurt.

>
> Hmmm, Just goes to show that human skulls, like eggshells, can be
> surprisingly strong. Can't say the same for the polystyrene hat he was
> weaing though, it looks like it just fell to bits. This is not
> surprising given all the holes in modern cycle helmets and the fact
> that they are only designed to absorb around 100 Joules of energy in
> an 'ideal world' crash situation. (And this is for 'Snell' certified
> helmets, a standard which is so 'high' that almost no helmets
> currently available meet it).


The standard for the flat anvil test part of B95-A is actually 110J.

The helmet isn't required to absorb this amount of energy during
certification testing. The test is described as "impact management" and the
idea is that the helmet remains in place and intact during a 110J impact and
keeps the peak linear acceleration of the headform below a value of 300g. A
very strong helmet shell may absorb plenty of energy but still impart
unacceptably high linear accelerations, a decent amount of controlled
crushing is required to keep the forces under control. While the test
standards are minimum requirements, it is most unlikely that a primary
design target of any helmet is that it fails catastrophically after
absorbing 111J.

>
> In a classic 'over the handlebars' crash where a 75 kg cyclist is
> doing only 15.6 Mph (7 m/sec) when a car pulls out and is hit by the
> cyclist who summersault forward and lands head first the kinetic
> energy carried by the airborne cyclist will be 1837 Joules, almost 17
> times the load imposed on the helmet when certified to Snell
> standards. If the helmet is the first point of impact it will simply
> bottom out (or, as often happens with a modern helmet, break up) and
> even if the helmet were to absorb all the energy it was designed to
> 94% of the energy developed in the crash must be dissipated by other
> means, which potentially includes dissipation via the riders skull,
> brain and body.


For the head of our unfortunate hypothetical cyclist to attract the whole
1837J he would have to possess a totally rigid body and impact a similarly
rigid obstacle with his centre of mass directly behind the impact point as
defined by his direction of travel - in zero gravity. In reality the body
of the cyclist behaves as a loosely connected mass/spring/damper system
which largely decouples (not in a literal sense, of course) the head from
the mass of the body. If we consider the head of the U.H.C. having to deal
with just its own kinetic energy we see that a typical 5kg effective head
mass travelling at 7m/s has a touch over 122J of the stuff - rather closer
to the Snell standard. Another thing to consider is that the 7m/s accident
velocity may not translate directly into the speed of impact with the rigid
obstacle, and if the impact velocity has a component tangential to the
obstacle's surface then the energy requirements are again reduced.

An aside: Formula 1 racing cars regularly have spectacular high speed
accidents which are rendered survivable by well designed energy management
structures to their front, side and rear. The amount of damage suffered by
the front nosecone in a ~160mph encounter with the tyre wall can be roughly
the same as that measured in approval testing, i.e. the amounts of energy
absorbed are in the same ballpark which shows that the test is a realistic
representation of what the structure might be called on to do in a real
crash. The test is carried out against a rigid wall at 35mph which suggests
that about 5% of the energy in the crash goes into the first point of
contact. Taking some liberties with the U.H.C. example and reading the
proportions across we see that his head whould have to absorb about 88J in
the impact. OK, I know that this is not scientific and proves nothing, but
it does illustrate the point I'm trying to make that the claims of enormous
energies required to be absorbed by the head, based on the K.E. of the whole
body, are rather misleading.

Given the fact that the skull is supposed to absorb 1000J before fracturing
it seems to be a wonder that skull fractures happen at all based on energy
considerations. Well, the clue is that no biomechanical injury predictors
for bone fracture use energy absorption as their measurement. The much
maligned, flawed (but still useful) H.I.C. uses head acceleration (force)
and time to predict the likelihood of skull fracture and other injury
predictions are made from forces, moments and deflections of bones and
joints.

It is obvious that much larger forces than even these
> may be generated should someone be struck by a large, unyielding motor
> vehicle travelling at speed, and this is without considering other
> such all important factors such as the creation of rotational forces
> within the brain in a violent road crash which may kill even when '
> direct impact' injuries such as skull fractures do not occur.


Of course, any safety system will reach the limit of its usefulness if too
much is asked of it. Plenty of people die in cars with seatbelts and
airbags.

>
> Do helmets genuinely 'save lives'? I have serious doubts myself...


Maybe, at the margins, although I suspect that anyone who emerges from their
accident relatively unscathed was not "saved" by their helmet, any more than
they were "saved" by their track mitts.

I think that we get too hung up on the supposed life saving properties of
helmets. Look again at the picture of Mr. Lipscomb and his helmet. The
helmet does appear to be badly cracked (although it's not really possible to
see the full extent of the damage from this one picture) but his head
appears to be unscathed. It the truck had run over his unprotected head,
and his skull not been damaged, I would expect to see rather more evidence
of the truck's passing on Mr. Lipscomb's person.

--

Nigel
 
N

Nigel Randell

Guest
Tony Raven wrote:
> Clive George wrote on 15/05/2007 19:47 +0100:
>> "Tony Raven" <[email protected]> wrote in message
>> news:[email protected]
>>> Clive George wrote on 15/05/2007 19:19 +0100:
>>>>
>>>> Go on then - what static load do you reckon the skull can take
>>>> sideways? And what load if it arrives in a careless fashion, as a
>>>> lorry wheel is wont to do?
>>>>
>>>
>>> I don't know but I will go and find out..........
>>> [time passes]
>>> .....5,000 - 31,000psi in static compression.
>>> Leestma J.E., Forensic Neuropathology, Raven Press, New York, 1988,
>>> Chapter 4

>>
>> That doesn't actually answer my question - what total sideways
>> crushing load? Point pressure is rather different.

>
> No that is area not point pressure.
>
>>
>> If I take four people with their heads placed sideways, would they be
>> able to hold up that double decker bus you mentioned in the same way
>> as the cups? I'm guessing not, because the stress isn't compressive
>> in the middle. If the sides of the skull are supported, maybe, but
>> without that won't they just fold?
>>

>
> It almost certainly will. Take the example of free divers. They have
> set a record so far of 150m depth. The water pressure at that depth
> is 15 atmospheres or 225psi. Given the dimensions of the head that is
> equivalent to a static loading of about ten tons on one side of the
> head. I am not aware of there being any concerns about their skulls
> being crushed at those loadings. The human skull is remarkably
> strong.


What's the pressure inside the skull?

--

Nigel
 
S

Simon Brooke

Guest
in message <[email protected]>, Tom Orr
('[email protected]') wrote:

>
> "dkahn400" <[email protected]> wrote in message
> news:[email protected]
> <snipped>
>> Ryan thinks his head was run over because he felt pressure from the
>> helmet while its tail was being crushed. That may well have been the
>> source of his reported concussion. This looks to me like yet another
>> case of a helmet credited with saving a life when actually it failed
>> to prevent, and may actually have promoted, a brain injury
>> (concussion).

>
> If you don't think that there is ANY situation in which a bicycle helmet
> can reduce the chances of injury and indeed actually make injury more
> likely why are you not actively campaigning to have them banned?


Because that isn't true. Helmets are very good at reducing grazes and
bruising to the scalp in minor falls at low speeds. If you're doing
technical mountain biking, or urban stunt riding, wearing a helmet is
quite sensible. If you're riding on the road, however, you are in
territory where the probability of a helmet aggravating a serious injury
probably outweighs the probability of it ameliorating a minor one.

It has to be a judgement call for the user: is protection from minor bashes
and bruising worth a very low risk of serious brain damage?

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

'Victories are not solutions.'
;; John Hume, Northern Irish politician, on Radio Scotland 1/2/95
;; Nobel Peace Prize laureate 1998; few have deserved it so much
 
R

Rob Morley

Guest
In article <[email protected]>, Clive
George
[email protected] says...
> "Simon Brooke" <[email protected]> wrote in message
> news:[email protected]
>
> >> His head wasn't crushed.

> >
> > Not necessarily. The air pressure in the tyres is somewhere between 30 and
> > 100psi. I think - I'm not sure - that a human skull ought to resist that
> > much pressure. I have no problem believing a truck went over his head
> > without breaking his skull, although I wouldn't like to guarantee you'd
> > always get away with it.

>
> Pressure - yes, provided it's a small enough area. But the force exerted by
> the tyres is quite large - a couple of tons at least.


If the truck was turning hard the inside wheels would have been
unloaded, so if it was an inside tyre that went over him there might
have been relatively little force involved.
 
S

Simon Brooke

Guest
in message <[email protected]>, Peter Clinch
('[email protected]') wrote:

> Marc Brett wrote:
>> For all you doubting-Thomases who think helmets don't work in real-world
>> collisions with vehicles.

>
> I'm not saying he'd have come out just as well without a helmet,


I think, actually, you can say /exactly/ that with a high degree of
certainty. The helmet certainly did not have the strength to resist the
crushing force. As it crushed, its only residual benefit could have been
to distribute the load evenly over the head. But the tyre would do that
better and more evenly without the helmet in the way - it is, after all,
what a pneumatic tyre is designed to do (and not what a helmet is designed
to do).

But in fact as pointed out by others on this thread it appears from the
photo that the wheel missed his head and ran over the rear extension of
his helmet - so if he had not been wearing it he would in all probability
have been entirely uninjured.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; If God does not write LISP, God writes some code so similar to
;; LISP as to make no difference.
 
P

Phil Armstrong

Guest
Rob Morley <[email protected]> wrote:
> If the truck was turning hard the inside wheels would have been
> unloaded, so if it was an inside tyre that went over him there might
> have been relatively little force involved.


Good point.

Which reminds me of the Penn & Teller trick where they ran a truck
over Teller after loading up the far side with enough mass to
completely unweight the wheels going over Teller & replacing the tyres
in question with soft foam ones.

Phil

--
http://www.kantaka.co.uk/ .oOo. public key: http://www.kantaka.co.uk/gpg.txt
 
N

Niall Wallace

Guest
"Rob Morley" <[email protected]> wrote in message
news:[email protected]
> In article <[email protected]>, Clive
> George
> [email protected] says...
>> "Simon Brooke" <[email protected]> wrote in message
>> news:[email protected]
>>
>> >> His head wasn't crushed.
>> >
>> > Not necessarily. The air pressure in the tyres is somewhere between 30
>> > and
>> > 100psi. I think - I'm not sure - that a human skull ought to resist
>> > that
>> > much pressure. I have no problem believing a truck went over his head
>> > without breaking his skull, although I wouldn't like to guarantee you'd
>> > always get away with it.

>>
>> Pressure - yes, provided it's a small enough area. But the force exerted
>> by
>> the tyres is quite large - a couple of tons at least.

>
> If the truck was turning hard the inside wheels would have been
> unloaded, so if it was an inside tyre that went over him there might
> have been relatively little force involved.


I am trying to visualise this an all i am seeing is lots of body roll with
the inside lower than the outside, suggesting there is more weight on the
inside suspension than the outside.. But thats on a car without Anti-roll
bars and on a roundabout turning right.

Niall
 
N

Nick

Guest
burt wrote:
> "Marc Brett" <[email protected]> wrote in message
> news:[email protected]
>> For all you doubting-Thomases who think helmets don't work in real-world
>> collisions with vehicles.
>>
>>
>> Bike helmet crushed, but head fine
>> http://www.madison.com/tct/news/index.php?ntid=133934
>>

>
> Just posted the response below:
>
> "Burtthebike says:
>
> This story is complete, total, utter nonsense.
>
>
> It may be true that the cyclist and the truck were in collision, but to
> claim that the cycle helmet saved his life after the truck ran over his head
> merely demonstrates that the cyclist was most definitely suffering from
> concussion. No cycle helmet will protect your head if you get run over by a
> relatively small car, let alone a truck! Hogwash dressed up to sell helmets
> and make the cyclist feel good.
>
>
> We've only got his word for it that it ran over his head, and given that
> that is impossible, the rest of his story must be open to question. As one
> of the other posters asked, where are the witnesses and why did no-one get
> the licence plate?
>
>
> Urban myth in the making. Believe this and demonstrate your gullibility and
> lack of independent thought."
>
>

I don't know about heads you're probably right it. Maybe it pinched the
helmet and poped his head out without actually going over it.

However one of my friends did get knocked off and a car went right over
his forearm with no significant damage. He did have a very clear tyre
pattern on his arm to prove that it happened.
 
T

Tony B

Guest
Nick wrote:

> However one of my friends did get knocked off and a car went right over
> his forearm with no significant damage. He did have a very clear tyre
> pattern on his arm to prove that it happened.


Years ago a mate of my older brother had the misfortune to be run over
by a lorry; the wheels went over his torso; wheel marks to prove it!. He
was in a very bad way although he didn't "pop" and made a full
(physical) recovery. But he did go a bit funny in the head...

hth,

Tony B