Stop Headway

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.
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Cunobelin
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Re: Stop Headway

Postby Cunobelin » 26 Sep 2010, 3:46pm

Jonty wrote:
Cunobelin wrote:Which is why cyclists are so dangerous!

1. Several thousand pedestrians are killed each year in vehicle accidents
2. One pedestrian is killed every few years by a cyclist
3. However the journey time and distances are greatly different.

When you correct these figures and put the "risk / exposure" into the equation - pedestrians are at greater threat from cyclists (and more likely to be killed by one) than from vehicles.


Cunobelin
Thanks for that but IMO you are not seriously addressing the points I have raised.
jonty


I believe solidly in the number of patients that cross the threshold of our Trust..... It is indisputable that head injuries occur and we know just how many there are. If we assume these can be alleviated, we can also see where the greatest benefit offered by helmet wearing could be achieved and it isn't with cyclists!


It is also interesting how "risk and exposure" are used to justify compulsion, but not allowed in other cases.... I am allowed to assess my risk and wear a helmet, but not allowed to asses my risk and not wear one!

Jonty

Re: Stop Headway

Postby Jonty » 26 Sep 2010, 6:43pm

drossall wrote:Surely, to know which basis of measurement (of danger) to use, you have to know what question is being asked?

If I am deciding whether to drive, cycle or walk for a particular trip, the distance won't change, so the risk per mile is relevant.

If I make an overall lifestyle decision, and I am typical, I'm prepared to live (say) an hour from work. If I choose to drive, I may well choose to live further away, and if I insist on walking, quite close. Then the risk per hour may be more relevant.

But then of course there are the health benefits...



True, as it applies to your experience and I'm in no position to disagre; however, the DfT figures which are quoted above are statistics which relate to many cyclists and pedestrians: they do not seek to explain one individual's behaviour.
Their statistical analysis is macro not micro.
Measuring safety in terms of fatalities per miles travelled is a valid way of going about it. But they are other ways of measuring it including fatalities per unit of time whilst engaged in the activity, and fatalities per journey.
Using different measures gives greater insight and understanding whereas only using one measure can be partial and misleading. .
According to the DfT figures cycling is a bit safer than walking on the basis of miles travelled but substantially much more dangerous whilst engaged in the respective activities, and per journey.
A number of posters on this forum are of the opinion that cycling is much safer than walking and have joked about the need to wear a helmet to go to the shops.
In fact there are good grounds for concluding that cycling is not safer than walking. On average the chances of being killed when cycling for an hour are about 4 times that of walking for an hour.
And the chances of being killed on a cycling journey/trip are on average about 4 times that of being killed on a walking journey/trip.
I'm not suprised by this.
jonty

drossall
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Re: Stop Headway

Postby drossall » 26 Sep 2010, 7:17pm

I think you'd have to say they were pretty-much the same then "on average". You couldn't tell whether someone using the figures was trying to decide how to get to the shops (cycling is safer on the basis of your statements*) or how to spend an afternoon off (walking is safer).

The differences are pretty small anyway (much less than an order of magnitude), so trying to measure them is not that constructive.

* This is actually quite a surprising result given general assumptions about "cycling is dangerous". Might be more useful to understand the basis of each set of figures than to argue about which is the most risky activity.

Pete Owens
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Re: Stop Headway

Postby Pete Owens » 26 Sep 2010, 8:14pm

Jonty wrote:
A number of posters on this forum are of the opinion that cycling is much safer than walking and have joked about the need to wear a helmet to go to the shops.

Wrong.

A number of posters have pointed out that cycling is slightly less risky than walking.
This is an activity considered so low risk by the general population that not only is a helmet not considered necessary by anyone, but to even to advocate such a ludicrous precaution would open the person suggesting it to ridicule.

The level of risk for cycling is broadly the similar (by whatever measure) - so what you are splitting hairs about is whether advocating cyclists wear helmets is slightly more or slightly less absurd than advocating it for pedestrians.

In fact there are good grounds for concluding that cycling is not safer than walking. On average the chances of being killed when cycling for an hour are about 4 times that of walking for an hour.

But since you will reach your destination in 10 minutes rather than an hour the pedestrian takes then the risk for the journey is lower.

However, if you a measuring risk per journey than the choice of mode is much less important than the distance of the journey. So rather than "cycle helmets" headway should be advocating "Long Journey" helmets.

If you were about to drive 400km from London to Edinburgh and some busy body from Headway told you you were irresponsible for not wearing a helmet would you (a) say what a good idea and get yourself kitted out - or (b) tell them not to be so stupid.
Is the chap you see running the London marathon (40km) wearing a viking helmet (a) a nutter or (b) the only one who read the safety briefing from the organisers.

Jonty

Re: Stop Headway

Postby Jonty » 26 Sep 2010, 9:04pm

Pete, thanks very much.
Can you please give me the reasons why you think my analysis set out in the post I made today at 10.50 am which is given above is flawed.
I've put forward a dispassionate case based on DfT's statistics.
I have yet to read a rational case against it by anyone IMO which speaks volumes. If you can identify flaws in my case, please let me have them.
I'm quite happy for you or anyone else to refer my analysis to the Royal Statistical Society or the DfT for their opinion.
jonty
PS
Your response to me saying "On average the chances of being killed when cycling for an hour are about 4 times that of walking for an hour" is "But since you will reach your destination in 10 minutes rather than an hour the pedestrian takes then the risk of the journey is lower".
Do you not see some rather obvious inconsistencies in your response?

irc
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Re: Stop Headway

Postby irc » 26 Sep 2010, 9:13pm

Jonty wrote:.
In fact there are good grounds for concluding that cycling is not safer than walking. On average the chances of being killed when cycling for an hour are about 4 times that of walking for an hour.
And the chances of being killed on a cycling journey/trip are on average about 4 times that of being killed on a walking


So close to zero then.

If cycle helmets are a good idea because cycling is 4x more risky (by time) than walking why are driving helmets not a good idea for cars which are more dangerous than trains?
No one believes more firmly than Comrade Napoleon that all animals are equal. He would be only too happy to let you make your decisions for yourselves. But sometimes you might make the wrong decisions, comrades, and then where should we be?

snibgo
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Re: Stop Headway

Postby snibgo » 26 Sep 2010, 9:54pm

Measuring deaths per hour rather than per kilometre, bikes and cars are equally safe (or unsafe).

So, following Jonty's line, if I need a cycle helmet, I also need a car helmet.

Jonty

Re: Stop Headway

Postby Jonty » 26 Sep 2010, 10:14pm

irc wrote:
Jonty wrote:.
In fact there are good grounds for concluding that cycling is not safer than walking. On average the chances of being killed when cycling for an hour are about 4 times that of walking for an hour.
And the chances of being killed on a cycling journey/trip are on average about 4 times that of being killed on a walking


So close to zero then.

If cycle helmets are a good idea because cycling is 4x more risky (by time) than walking why are driving helmets not a good idea for cars which are more dangerous than trains?


Irc
And I thought we were getting close on this one!
I HAVEN'T said that cycle helmets are a good idea BECAUSE cycling is 4 times more risky (by time) than walking.
What I said is that cycling is about 4 times more risky (by time) than walking and that a cycling trip is about 4 times more risky than a pedestrian journey, and that is a useful way to look at it.
THAT IS ALL I HAVE SAID.
For the record for the umteenth time, I do think Helmets are a good idea but, on the information which is currently available, I am not in favour of compulsion.
The REASON why I'm in favour of wearing a helmet of the highest standard is because I consider that it can offer some limited protection in certain circumstances, and that's good enough for me. It may not be good enough for everyone, but it's good enough for me.
It's NOT because cycling is about 4 times more risky (by time) than walking and I have never said this.
I'm not going into cars, trains and planes. I used to work in those fields and I've had enought of it.
jonty
ps
I'm cycling tomorow, thank God.

Steady rider
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Re: Stop Headway

Postby Steady rider » 26 Sep 2010, 11:37pm

UK
Rates killed per 100 million km
Urban roads, ‘A‘ roads, Other roads
Car 0.2, 0.1
cyclist 4.7, 0.5
Motorcyclist 8.4, 5.3

Rural roads, ‘A‘ roads, Other roads
Car 0.5, 0.6
cyclist 24, 3.2
Motorcyclist 17, 12
---------------
The 24 figure, rural A roads, would be 240 per billion km, compared with 5 per billion km for 'other' urban roads, 48 times higher risk.

Currently the Netherlands has a rate of about 11 per billion km, UK 24 per billion km, for cycling in general. The problem seems to be reducing this level of risk on rural A roads in the UK.
------------
The issue of helmets is a bit of red herring in some ways.

Erke and Elvik (Norwegian researchers) 2007 stated: "There is evidence of increased accident risk per cycling-km for cyclists wearing a helmet. In Australia and New Zealand, the increase is estimated to be around 14 per cent."

Cycling by secondary school children in Sydney reduced by 67% following helmet legislation.
in New South Wales the extra number of children wearing helmets was 569 compared with 2658 fewer cycling.

Robinson 1996 report, Table 2 shows data for children in NSW. The equivalent number of injuries for pre law level of number of cyclists increased from 1310 (384 head + 926 other injuries) in 1991 to 2083 (488 head + 1595 other injuries) in 1993. For NSW the helmet laws reduced children’s safety. The increased injury rate was 59%, from 1310 to 2083.
---------------
UK
Helmets have confused the issuses here, A roads are a serious problem and the objective is lowering the accident rate but the data on helmets shows the opposite effect may occur. We should really be discussing how to reduce accidents but helmets and helmet laws distract from addressing the other issues.

The problem with Headway is they convey the message helmets are safe and take up time that could be spent on addressing the main problems.

Pete Owens
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Re: Stop Headway

Postby Pete Owens » 27 Sep 2010, 12:38am

Jonty wrote:Pete, thanks very much.
Can you please give me the reasons why you think my analysis set out in the post I made today at 10.50 am which is given above is flawed.
I've put forward a dispassionate case based on DfT's statistics.

The flaw is that you never compare like with like.

For any pedestrian journey from A-B the cycle journey will be the same distance - thus slightly safer.
So if is absurd to suggest that protective headgear is sensible for a pedestrian making that journey then it follows that it is equally absurd to advocate it for cyclists. The argument applies to ANY journey.

Now answer some questions straight.
1) Do you wear a pedestrian helmet - ever?
2) If not why not?
3) If you had to take a long journey in a motor car would you wear a helmet?
4) If not why not?
5) What reception do you think that you would get if you suggested to a group of pedestrians that they should wear helmets?
6) ditto motorists?
7) Do you notice how polite and patient we cyclists are in comparison?

Now rather than address this argument directly you move the goalposts so rather than comparing walking from A-B to riding to the same destination you come up with a longer journey from Y-Z.

Fair enough lets consider this longer journey. I think you suggested 8km as the threshold. Now I think the DfT stats put the risk for cycling at about 15 times the risk driving so 8km would be equivalent to 120km drive (maybe not typical, but not unusual). So lets consider the 400km up the A1 from London-Edinburgh. Again to suggest that it would be a sensible precaution to wear a helmet to drive from London to Edinburgh would be absurd - thus it is equally absurd to advocate helmets for cycle trips under 30km (that pretty much covers the vast majority of cycle trips). Keep on going up the A9 to Inverness and beyond and you will still see no drivers wearing lids.

Steady rider
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Re: Stop Headway

Postby Steady rider » 27 Sep 2010, 10:52am

400km up the A1 from London-Edinburgh, possibly 400 miles perhaps.

How can helmets be safe if they increase the accident rate?

http://www.theage.com.au/victoria/cycli ... 15ro3.html

Flinders
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Re: Stop Headway

Postby Flinders » 27 Sep 2010, 3:06pm

The decision of an individual on whether to wear one or not is simple enough.

Perhaps I can explain.

First question,
Given the sort of accidents I personally am likely to encounter (i.e.what type, at what speed, on what terrain) would wearing a (specific) helmet be more likely to add to my protection overall or lessen it?
In my case, on balance the helmet I have chosen would add to my protection in most accidents I'd be likely to have. So, the next question is-

Am I willing to endure any discomfort it may produce in order to gain the protection it offers?

To decide that, I have to decide, how much discomfort does it produce? For the helmet I have now, the answer is, natch, as I forget I'm wearing the thing. It's well vented and light.

So it's easy for me to decide. I wear one.

Answer these questions for yourself and then do what you like. But it is clear from the two questions that saying that 'people' should, or should not, wear one, is unintelligent, as the answers to both questions depend entirely on the sort of cycling an individual does and the comfort they are willing to sacrifice (if any), which will be different for every cyclist. That's why I'm against both compulsion and stupid generalisations on either side of the argument.

Steady rider
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Re: Stop Headway

Postby Steady rider » 27 Sep 2010, 6:54pm

Interesting way to view the topic.

The rotational tests found for the larger helmet size the results indicated a higher risk from wearing one.
http://www.cyclehelmets.org/1182.html
However, for the most severe cases using a size 57cm (J) headform, rotational acceleration was typically greater than 10,000rad/s² and increased to levels of 20,000rad/s², a level at which a 35% - 50% risk of serious AIS3+ injuries is anticipated

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Cunobelin
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Re: Stop Headway

Postby Cunobelin » 27 Sep 2010, 9:21pm

Risk is fine, but lets simplify this...

If we accept for a moment that helmets do have a positive impact and do prevent or alleviate injuries.

Lets assume that a random number say 30% of head injuries would be prevented or reduced if the victim wore a helmet

Now lets look at a typical 100 admissions:

39 pedestrians
9 Cyclists
12 motorcylists
25 drivers
16 vehicle passengers

Now the head injury reduction achieved would be:

13 pedestrians
3 cyclists
4 motorcylists
8 vehicle drivers
5 vehicle passengers

Therefore the greatest reduction in cost, and benefit to the population would not be for cyclists....... how can anyone justify saving 3 victims by advocating cycle helmets, yet allow 13 pedestrian head injuries or 13 vehicle occupants when they could equally be saved by the simple expedient of wearing the same helmet?

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Re: Stop Headway

Postby SilverBadge » 27 Sep 2010, 10:46pm

Cunobelin wrote:Which is why cyclists are so dangerous!

1. Several thousand pedestrians are killed each year in vehicle accidents
2. One pedestrian is killed every few years by a cyclist
3. However the journey time and distances are greatly different.

When you correct these figures and put the "risk / exposure" into the equation - pedestrians are at greater threat from cyclists (and more likely to be killed by one) than from vehicles.
Are you sure about that? Factoring in the distances will certainly skew the figures back towards cyclists but not automatically make them the greatest threat. For the UK there are several hundred pedestrian deaths annually - as you say, the cyclist "kill rate" averages well below 1. Which would require cycling to be well below 0.1% of the total UK mileage for deaths per mile to equal that from cars. I asked this very question a couple of months back as I couldn't dig out figures for the relative numbers of pedestrian deaths per "vehicle" mile - think I orignally saw them in something CTC though they were DTp figures. Per large round unit, cycles were about 1, cars 4, light goods 7, HGV 8 and motorbikes 16. If you have any actual stats I would be grateful if you could share them.