Stop Headway - Campaign

This sub-forum all discussions about this "lively" subject. All topics that are substantially about helmets will be moved here, if not placed here correctly in the first place.
MartinC
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Location: Bredon

Re: Stop Headway - Campaign

Postby MartinC » 27 Sep 2010, 2:39pm

7_lives_left wrote:
snibgo wrote:What deceleration (and over what time) causes decapitation, or less spectacular death, or irreversible brain damage, or a mild headache? I don't know. Why does the Snell standard specify 300g rather than 200g or 400g? I don't know.

Perhaps the various standards that specify maximum allowed deceleration are based on some research. Or perhaps they are wild guesses.

No they are not wild guesses. Don't know how to put this delicately, but at some point someone will have carried out a test on a cadaver. The results of that test will have been used as a benchmark so that when they do subsequent tests, they don't have to use a cadaver each time. Much more pleasant for the testers that way.

Wikipedia:Crash test dummy-Cadaver testing


Testing a cadaver to see what level of impact causes death or serious brain injury sounds like it would have to be an interpretation based on a set of assumptions and, by definition, not an objective test. Nevertheless the results would be interesting so it would be good to see what they were and how they've been applied to cycle helmet design - is this in the public domain?

MartinC
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Joined: 10 May 2007, 6:31pm
Location: Bredon

Re: Stop Headway - Campaign

Postby MartinC » 28 Sep 2010, 9:14am

7_lives, sorry, I've tried asking this delicately but there's been no response. Are you saying that you know what Snell's rationale was based on and will you share it with us?

SilverBadge
Posts: 577
Joined: 12 May 2009, 11:28pm

Re: Stop Headway - Campaign

Postby SilverBadge » 29 Sep 2010, 3:34pm

MartinC wrote:Testing a cadaver to see what level of impact causes death or serious brain injury sounds like it would have to be an interpretation based on a set of assumptions and, by definition, not an objective test. Nevertheless the results would be interesting so it would be good to see what they were and how they've been applied to cycle helmet design - is this in the public domain?
There are various invasive (recommended only for dead people) and non-invasive methods of establishing what brain trauma has been caused by an accident. And if the person was live and compos mentis before the accident and less so afterwards, you have the "effect" of the accident. If you put various (healthy?) cadavers through various "example" accidents, stick some instrumentation on to measure decelerations, examine the brain tissue afterwards, you can correlate impact magnitude with tissue damage sustained and thus likely outcome (temporary/permanent brain damage, death etc). And repeating accident scenarios with helmets / seatbelts / airbags can then establish the reduction in impact and thus the benefit of the safety measure for a scenario (uninjured vs mentally impaired, cabbage vs dead etc). Cadavers weren't perfect, IIRC they had to be pressurised and maybe warmed through to behave realistically. These days, EuroSID and the like do just as good a job, if not better.

MartinC
Posts: 1840
Joined: 10 May 2007, 6:31pm
Location: Bredon

Re: Stop Headway - Campaign

Postby MartinC » 29 Sep 2010, 6:28pm

SilverBadge wrote:
MartinC wrote:Testing a cadaver to see what level of impact causes death or serious brain injury sounds like it would have to be an interpretation based on a set of assumptions and, by definition, not an objective test. Nevertheless the results would be interesting so it would be good to see what they were and how they've been applied to cycle helmet design - is this in the public domain?
There are various invasive (recommended only for dead people) and non-invasive methods of establishing what brain trauma has been caused by an accident. And if the person was live and compos mentis before the accident and less so afterwards, you have the "effect" of the accident. If you put various (healthy?) cadavers through various "example" accidents, stick some instrumentation on to measure decelerations, examine the brain tissue afterwards, you can correlate impact magnitude with tissue damage sustained and thus likely outcome (temporary/permanent brain damage, death etc). And repeating accident scenarios with helmets / seatbelts / airbags can then establish the reduction in impact and thus the benefit of the safety measure for a scenario (uninjured vs mentally impaired, cabbage vs dead etc). Cadavers weren't perfect, IIRC they had to be pressurised and maybe warmed through to behave realistically. These days, EuroSID and the like do just as good a job, if not better.


I think we're agreeing. The testing you describe is what I'd expect. The point I was making was that It's not direct but interpretive. You can't measure the soft brain tissue damage in a cadaver 'cos it'll bleed differently, you can't measure the blood flow, you can't measure the severed nerve connections and you can't directly assess the impact on brain function. You can only infer what's likely to have happened - i.e. interpret based on your assumptions. Also because you're not dissecting and examining people who've survived a measured blow then you can't establish what's survivable. Inficting calibrated blows on live samples is a bit extreme!

Nevertheless useful and informative but you'd have to do it on a very large scale to establish reliable correlations between impact types and level of brain injury.

It would be useful to know how what was discovered has been applied to cycle helmet design - but I suspect that nobody here knows.

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Cunobelin
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Re: Stop Headway - Campaign

Postby Cunobelin » 29 Sep 2010, 7:22pm

mattheus wrote:You're more likely to get lacerations and bruising on your knees, elbows, hands (and possibly shoulders and hips, but we cover those most of the time already) - just google for some pictures.
None of the above are life-threatening. I might worry about a bruised/cut cheek if I were a model, but at the moment they are a very low priority.

If you're worried about them, wear a helmet - (almost) noone is stopping you :) (But please also consider knee-pads, elbow pads, gloves, face-guard ... )


THe British Dental Association is certainly looking at increased facial protection and as Headway is quoting the paper implies they are in agreement with this so compulsory full face helmets are what Headway is suggesting