Helmets - the definitive thread.. ** Mod Note - Please read Opening Post **

tomasrojo

I didn't think that one through! "strictly speaking" -> "generally speaking"

Jawgap

From that other thread.......

Wanderer78 wrote: »

when is ireland gonna introduce mandatory use of helmets with on the spot fines?? no brainer!!!

Good idea - cyclist jumps lights / cycles on path etc and is stopped by Guard.

Guard should be able to offer him / her 3 options:

• An FPN payable within 28 days
• A free trip to the district court to play for the big money prize
• A helmet of shame......to be worn from that point forward......

.....or they could just go with the FPN option.

tomasrojo

St. Chris on this subject again:

Chris Boardman has said that he “won’t waste air time” discussing the safety effects of helmets and says the debate over them is “being used to deflect from making real decisions” about cycle safety.

www.cyclingweekly.co.uk/news/latest-news/boardman-helmet-debate-being-used-to-avoid-making-real-decisions-186541

It would be nice if any media discussion of cycling didn't devolve into helmets (and hi-viz) within four sentences.

Tenzor07

Interesting post from Australia, the most fervent anti-cycling country around!

http://www.theguardian.com/lifeandstyle/2015/aug/12/mandatory-bike-helmet-laws-do-more-harm-than-good-senate-hears

tomasrojo

Qualitymark posted this in another thread on MIPS helmets, and I think it's worth placing here:

http://www.bhsi.org/hodgstud.htm

Quite an old study, but has a shot at doing skid tests, which have a component of a standard bike fall not covered by the simple "drop the helmet onto an anvil" standard tests. Suggests old-fashioned hard-shell helmets snag less.

(I haven't read it in enormous detail. Curious commentary about setting a good example to children that doesn't really belong in a scientific paper. Speed range of the falls looks unrealistically low, for fear of damaging the sensors in the equipment.)

Doctor Bob

The RSA's Annual Academic Road Safety Lecture this year - on Monday 5th - is relevant to this thread:

This year, the theme of the lecture is ‘Cycling Safety’. The lecture will be chaired by RTÉ Broadcaster, Mr Bryan Dobson. Minister for Transport, Tourism and Sport Paschal Donohoe TD will deliver the Welcome Address and Ms Moyagh Murdock, RSA Chief Executive will close the lecture. The two key speakers will be Mr Seamus Morris, Director National Spinal Injuries Unit, and Clinical Lead Department of Spinal Injuries Unit, Mater Misericordiae University Hospital who will present his research on cycling injuries, and Prof Michael Gilchrist, Head of the UCD School of Mechanical and Materials Engineering, who will present his research into cycling and helmet wearing.

It seems to be by invitation only. Hopefully they'll publish the papers, or someone here might be on the invitation list and could report back.

galwaycyclist

In the meantime this paper was presented last week at a conference in Hanover

http://www.fietsberaad.nl/?lang=nl&repository=Overestimation+of+the+effectiveness+of+the+bicycle+helmet+by+the+use+of+odds+ratios

The risk of getting a head injury per kilometre wearing a helmet relative to the same risk without helmet is the most appropriate measure to assess the effectiveness of the bicycle helmet. Due to lack of data on exposure rates, odds ratios of helmeted versus unhelmeted cyclists for head injury and other injuries on hospitalized victims are broadly used in case-control studies.
A general necessary and sufficient condition can be formulated rigorously, for which odds ratios indeed equal risk ratios. However, this condition is not met in case-control studies on bicycle helmets. As a consequence, the real risk of cycling with a helmet can be underestimated by these studies and therefore the effectiveness of the bicycle helmet can be overestimated. The central point is that a wrong estimate of the risk for non-head injuries (the controls) paradoxically can lead to an overestimation of the usefulness of the helmet in protecting against head injuries.

Three cases could be found in the literature with sufficient data to assess both risk ratios and odds ratios: the Netherlands, Victoria (Australia) and Seattle (U.S.A). In all three cases, the problem of overestimation of the effectiveness of the helmet by using odds ratios did occur. The effect ranges from small (+ 8 % ) to extremely large ( > + 400 %). Contrary to the original claim of these studies, in two out of three cases the risk of getting a head injury proved not to be lower for helmeted cyclists. Moreover, in all three cases the risk of getting a non-head injury proved to be higher for cyclists with a helmet.

It must be concluded that any case-control study in which the control is formed by hospitalized bicyclists is unreliable and likely to overestimate the effectiveness of the bicycle helmet.

As a direct consequence, also meta-analyses based on these case-control studies overestimate the effectiveness of the bicycle helmet. Claims on the effectiveness of the bicycle helmet can no longer be supported by these kind of studies. This might explain the discrepancy between case-control studies and other studies, such as time-analysis. It is recommended to use other methods to estimate the risk ratio for the bicycle helmet, along the lines described in this article.

tomasrojo

Doctor Bob wrote: »

The RSA's Annual Academic Road Safety Lecture this year - on Monday 5th - is relevant to this thread:



It seems to be by invitation only. Hopefully they'll publish the papers, or someone here might be on the invitation list and could report back.

They were supposed to have a media launch about Gilchrist's research last Christmas, I seem to remember.

tomasrojo

Yeah, there it is. Last Christmas.

http://www.irishexaminer.com/lifestyle/features/time-to-use-your-head-and-wear-a-helmet-when-cycling-302523.html

tomasrojo

That paper looks very interesting, galwaycyclist. Given how incompatible with population-level studies case-control studies have turned out to be, that would make sense.

monument

Doctor Bob wrote: »

The RSA's Annual Academic Road Safety Lecture this year - on Monday 5th - is relevant to this thread:



It seems to be by invitation only. Hopefully they'll publish the papers, or someone here might be on the invitation list and could report back.

From the Irish Examiner:

But a number of as yet unpublished academic studies conducted under the direction of Professor Michael Gilchrist, head of the UCD School of Mechanical & Materials Engineering as part of the RSA’s Academic Bursary Programme, have provided evidence of the protective benefits of helmets, particularly in lower speed collisions (50km/h) and in secondary collision impacts.

Prof Gilchrist’s research is due to be published by the Road Safety Authority before Christmas.

http://www.irishexaminer.com/lifestyle/features/time-to-use-your-head-and-wear-a-helmet-when-cycling-302523.html

CramCycle

Taking them along time to massage those stats. I heard mention of those reports coming out last year but to no avail.

He may or may not be right but I get the impression the conclusion was written and they have worked back from there.

Would love to be proven wrong although compulsory wearing still sounds insane, Boardman has the right idea. Far more important issues to be tackling for road safety.

HivemindXX

monument wrote: »

protective benefits of helmets, particularly in lower speed collisions (50km/h) and in secondary collision impacts

Lower speed than what I wonder? I thought that 30kph was the usual "low speed" benchmark. I wonder which would have the bigger effect in a cyclist/car collision. Whether the cyclist is wearing a helmet or whether the car speed is reduced from 50kph to 30kph.

Seweryn

CramCycle wrote: »

..compulsory wearing still sounds insane...

I hope this is never going to happen. It would destroy the Dublin Bike and other bike schemes in the country.

galwaycyclist

monument wrote: »

From the Irish Examiner:

But a number of as yet unpublished academic studies conducted under the direction of Professor Michael Gilchrist, head of the UCD School of Mechanical & Materials Engineering as part of the RSA’s Academic Bursary Programme, have provided evidence of the protective benefits of helmets, particularly in lower speed collisions (50km/h) and in secondary collision impacts.

Prof Gilchrist’s research is due to be published by the Road Safety Authority before Christmas.

http://www.irishexaminer.com/lifestyle/features/time-to-use-your-head-and-wear-a-helmet-when-cycling-302523.html

Professor Gilchrist's team may well find much "evidence of the protective benefits of helmets". Regardless, I suspect it is unlikely they will also produce evidence that this protection should only apply to cyclists rather than also applying to motorists and pedestrians.

Either head injuries are an issue that require helmets or they are not. The argument that helmet wearing should be mainly a matter for cyclists is spurious in my view.

Lumen

The situation has always been the same for cyclists, drivers and pedestrians, in that helmets are available for all but mandatory for none. The bike industry just has better marketing.

galwaycyclist

I did a quick Google on Prof Gilchrist - as always there is a health warning on the analysis below - this just based on a quick read and should be taken as indicating points that merit further discussion.

I found this

Comparative head injury risk analysis for cyclists wearing helmets during collisions: Real-world case investigations
T.T. Than*, M.D. Gilchrist*
http://bast.opus.hbz-nrw.de/volltexte/2013/692/pdf/41_Than.pdf


Apparently this is a modelling exercise based on an actual cycling fatality.

It would seem that this work is being funded by the RSA

Currently, the Irish Road Safety Authority is funding a project being undertaken at University College Dublin to study the protective performance of cycle helmets. The main objective of this project is to pave the way for recommended policies which will reduce cyclist fatalities and injuries. In order to study the kinematics involved in cyclist collisions as well as the specific injuries mechanisms and points of contact on the vehicles, a number of real collisions for which data from police reports and coroner reports was available have been reconstructed using mathematical dynamic model (MADYMO) simulation software. One of these fatality cases involved a male cyclist from a rural setting, for which the methodology as well as the results are presented in this paper.

The abstract for this paper bears very careful reading - my emphasis in bold.

Abstract Cycle helmets have continued to increase in popularity since their introduction half a century ago. Many studies indicate that overall, head injury can be significantly reduced by wearing them. This study was conducted using two distinct sets of real-world cycling collision data from Ireland, namely cases involving police collision reports and cases involving admission to a hospital emergency department. The analyses sought to simulate and analyse the protective performance of cycle helmets in such collision scenarios, by comparing the Head Injury Criterion score and peak head accelerations, both linear and angular. Cycle collisions were simulated using the specialised commercial software MADYMO. From the simulation results, these key metrics were compared between the same-scenario helmeted and unhelmeted cyclist models.

Results showed that the inclusion of bicycle helmets reduced linear accelerations very significantly, but also increased angular accelerations significantly compared to unhelmeted situations. Given the modest protective performance of cycle helmets against angular accelerations, it is recommended that cycle helmet manufacturers and international test standards need to pay more attention to head angular accelerations

The significance of this is that angular acceleration may be one of the things that causes brain injury. If you are increasing angular acceleration then it may be that you are increasing the risk of brain injury.

Does anyone here recall the RSA announcing that they had commisioned research that indicated that helmets might increase the risk of certain types of brain injury? It seems like an important finding and one that would need to made public.

The reason for the increase is not well discussed in the paper. They remark on a reduction in peak angular acceleration but don't appear do discuss any overall increase.

This is a screen grab of figure 15



If I am reading it right then blue is helmet and orange is no helmet. There is an angular acceleration event for the helmet case at the very start. I cant tell if there was an equivalent event for the non helmet case but if there was it is completely masked. This may be the source of the finding that there was an increase in angular acceleration. Unfortunately they don't give them as two separate graphs.


This phrasing might be a bit confusing

Effect of wearing a helmet
As seen in Figures 13-15, the wearing of a cycle helmet in this particular real-world case decreased peak head linear acceleration for almost 55%, but only about 15% for head angular acceleration.

A HIC score of almost 25000 was recorded in the simulation at the moment of head impact with the ground. Since a HIC score of such value corresponds to a fatal collision, this correlates with the actual fatality sustained. The maximum angular acceleration also occurred at the moment of secondary head impact. There are many studies linking head angular acceleration with brain injuries, especially diffuse axonal injury, as this is caused primarily by head angular acceleration [12].

The reason I find it potentially confusing is they only give a graph for the HIC score for the non-helmet case. However taken on face value "Effect of wearing a helmet" => "A HIC score of almost 25000" it suggests that a helmet wearer would have died anyway even if the helmet partially reduced the linear acceleration.

Time to get back to real work.

Edit: HIC = "Head Injury Criterion"
Edit 2: It looks like this paper is from 2013

Edit 3: I had another look and in Figure 13, the unhelmeted HIC score over time does show a peak at the start. However this is nothing like the same relative size of the peak for angular acceleration seen at the start for the helmet case in Figure 15.

A Jeffers

Angular acceleration would not necessarily increase the chance of brain injury, but more likely to cause bad neck injury by rotating the head. But there is a distinct chance that brain injury could also increase over less angular acceleration.

tomasrojo

I think the current understanding (which I get the impression is far from set in stone) is that rotational acceleration tends to lead to the more severe forms of brain injury, due to shearing of layers in the brain.

Woodpeckers, for example, avoid brain damage, despite constantly using their head as a hammer, by lining up their heads very precisely with the target before each blow (among other adaptations). So it seems to be something to avoid.

galwaycyclist

tomasrojo wrote: »

I think the current understanding (which I get the impression is far from set in stone) is that rotational acceleration tends to lead to the more severe forms of brain injury, due to shearing of layers in the brain.

Woodpeckers, for example, avoid brain damage, despite constantly using their head as a hammer, by lining up their heads very precisely with the target before each blow (among other adaptations). So it seems to be something to avoid.

While we should not rely on wikipedia it can make a good place to start

Diffuse Axonal Injury
https://en.wikipedia.org/wiki/Diffuse_axonal_injury

Diffuse axonal injury (DAI) is a brain injury in which damage in the form of extensive lesions in white matter tracts occurs over a widespread area. DAI is one of the most common and devastating types of traumatic brain injury,[1] and is a major cause of unconsciousness and persistent vegetative state after head trauma.[2] It occurs in about half of all cases of severe head trauma.

Mechanism

Unlike brain trauma that occurs due to direct impact and deformation of the brain, DAI is the result of traumatic shearing forces that occur when the head is rapidly accelerated or decelerated, as may occur in auto accidents, falls, and assaults.[7] It usually results from rotational forces or severe deceleration.[8][9] Vehicle accidents are the most frequent cause of DAI; it can also occur as the result of child abuse[10] such as in shaken baby syndrome.[11]

Which brings us back to increased angular acceleration.

Jawgap

Study Finds That Bicycle Helmets Most Effective in Low Speed Collisions

RSA Academic Lecture Marks First Day of Irish Road Safety Week A UCD Professor who conducted a study of cyclists with fatal head injuries has recommended that bicycle helmets are worn to protect against head injuries in the event of a collision, particularly at speeds of less than 50km/h.

The results of the study were presented at the annual Road Safety Authority (RSA) Academic Road Safety Lecture which took place in the Royal College of Physicians today (Monday 5 October). The lecture, which was chaired by RTÉ Broadcaster Bryan Dobson, marked the first day of ‘Irish Road Safety Week’ which runs until Sunday 11 October and focuses on three key areas – cycling safety, tyre safety and child safety.

The theme of today’s lecture was ‘Cycling Safety’ and featured a presentation from Professor Michael Gilchrist, Head of School of Mechanical and Materials Engineering at University College Dublin (UCD) who presented the results of his study ‘Analysis and Reconstruction of Bicycle Accidents’ which was conducted as part of the RSA Academic Bursary Programme.

In his study, Prof Gilchrist and his team used data from 37 fatal collisions involving cyclists in Ireland over a 10 year period and staged computer reconstructions to determine whether a helmet would have offered protection. The study found that bicycle helmets offer effective protection at low speeds of less than 50km/h but their protective capabilities are reduced as speeds increase.

I like that the definition of low speed is less than 50 km/hr :eek:

doozerie

Jawgap wrote: »

Study Finds That Bicycle Helmets Most Effective in Low Speed Collisions

The RSA are clearly still sticking to their mantra that wearing a helmet and hi-viz clothing are the highest priorities when it comes to road safety for cyclists, with “abiding by the Rules of the Road” (which I’m optimistically assuming they believe to cover the use of lights on a bike) coming in a poor third. There are matching quotes in that regard from both the Minister for Transport and the RSA Chief Executive, in the article above, which probably counts as progress in the name of cyclist safety as far as the RSA are concerned.

If I’m being cynical their approach strikes me as being along the lines of “yerra you’re going to have an accident anyway, so we won’t focus on how to avoid/prevent accidents we’ll go straight to what we thing are fantastic options to mitigate the effects of your certain collision, polystyrene is yer only man”. Personally, if I thought a collision was inevitable I’d be very concerned about my eyes (wear shatterproof glasses), my back (wear something protective over the spine), my hands (wear decent gloves), etc., etc. The RSA’s repeated failure to express concern over potential loss of my eyesight, potential paralysis, etc., makes me wonder how much they value my safety at all. ’Tis scandalous, Ted!

I’m impressed by this statement from their web page above though:

To date this year, 121 people have been killed on Irish roads to promote the need to stay safe on the roads, 24 fewer than the same period last year.

It’s very selfless of people to sacrifice themselves in the cause of promoting the dangers of using the roads. The RSA should probably be promoting less drastic approaches, only suggestions in helmet-clad and hi-viz -wrapped envelopes will be entertained though. Such envelopes are available from all conscientious stationary shops.

PaulieC

http://www.irishtimes.com/news/ireland/irish-news/donohoe-rules-out-making-cycle-helmets-compulsory-1.2379891

tomasrojo

Thanks. Will put in helmet megathread.

tomasrojo

http://www.irishtimes.com/news/ireland/irish-news/donohoe-rules-out-making-cycle-helmets-compulsory-1.2379891

Posted elsewhere.

On the bright side, bike-share schemes have inoculated us against helmet laws.

On the not so bright side:

Reference to RSA's amateurish (or misleading) statistical analysis:

He told the conference, which is part of Road Safety Week, there was a “complete mismatch” between cyclists accounting for only 2 per cent of all road users, but 8 per cents of all injured.

(For those with short memories, the RSA conflated serious and minor injuries for one year alone to get the number up to 8%. Cyclists typically make up way fewer than 8% of all injured, and even in that one year the serious injuries viewed on their own aren't anomalously high.)

Head nod to Thompson, Rivara and Thompson's much contested Cochrane Review as well.

Not sure what they expect helmets to do about all the spinal injuries, but it's interesting to see people framing healthy, benign travel in terms of death and impairment without reference to cars.

doozerie

tomasrojo wrote: »

Not sure what they expect helmets to do about all the spinal injuries, but it's interesting to see people framing healthy, benign travel in terms of death and impairment without reference to cars.

Absolutely. I've become so used to people reacting with shock to the fact that I commute by bicycle that I no longer find it as mystifying a reaction as I really should.

I can't swim, but I don't recoil in horror at the idea of boarding a boat. I can't fly, but I'm not shocked that people travel by plane. Boats sink, planes crash, but generally speaking people maintain a rational perspective and don't believe these to be anything other than rare tragedies. But apparently cycling, and particularly commuting by bicycle = certain death or serious injury, according to many.

People get irrational about the strangest and simplest of things, it seems. And, as per your reference above, many of these people will happily climb into a car and utterly believe, with the same conviction with which they believe that cyclists are suicidal, that they are taking the logical and safe option. Bizarre.

tomasrojo

Not to mention that if cycling is disproportionately likely to result in death of impairment, there are other strategies to change that, reducing the danger at source.

doozerie

Wow, I just read that Irish Times article and it's a catalogue of figures, presented as incontrovertible truths, portraying cycling as extremely dangerous. I despair.

tomasrojo

The repetition of the 2%/8% "mismatch" is especially depressing. It's such a flimsy bit of stats, and is really only about minor injuries (if it's about anything).

kenmc

thank fcuk