Jumping red lights is safer?

Please note that this item was not written by Colin!


On 04/24/07 20:14>

Tonight's Evening Standard tells us that "Male cyclists who jump red
> lights 'are safer'." Below is the full text of the article, lifted
> from
> http://www.thisislondon.co.uk/news/article-23393622-details/Male+cyclists+who+jump+red+lights+%27are+safer%27/article.do

What should LCC's response be? Silence, agreement, a call for better training targeted at women, a campaign to promote awareness of the dangers of being caught on the blind-side of a driver turning left?

Our first response should be to help people understand the stats, and not draw unwarranted conclusions.

(I'm sorry if the below is a bit verbose and many of you know all this, but the misconceptions about this are so prevalent that I feel compelled to elaborate).

Let me explain:

Quoting the "thisislondon.co.uk" article (but this has appeared all over the media): According to the study, 86 per cent of women cyclists killed in London between 1999 and 2004 were in collision with a lorry. This compares with 47 per cent for men.

Fine. Now read this very carefully. All it says is that (a) women cyclists *who get killed* get killed more often by a lorry (86 percent) than male cyclists *who get killed* get killed by a lorry (47 percent), and (b) women cyclists *who get killed* get killed much more often by a lorry than by another vehicle (86 vs 14 percent) and men cyclists *who get killed* get killed about equally often by a lorry as by another vehicle (47 vs 53).

The first question here should be: So what? (you can't imagine how often when people throw
around statistics this should be the first question). Why should we care? I'm a female cyclist, and if one day a vehicle kills me, I don't give two hoots whether it's a
lorry or a car than has run me down. Dead is dead.

Of course, people take the above stats to mean something completely different, namely:
"Women cyclists are more likely to be killed by lorries than men".

This is *cannot* be concluded at all from the above stats, so to make this statement without any additional data is wrong.

Equally wrong is the other conclusion made by many headlines:

-- Male cyclists ... 'are safer' (thisislondon.co.uk)
-- Women cyclists 'risk death' [implied: more than men
cylcists] ... (times online)

Why are they wrong?

(1) "Women are more likely to be run over by a lorry than men"

We need more data to make that statement.

Why? It could be that men and women are equally likely to be killed by a lorry, but that male cyclists are more likely to be killed by other types of vehicles than women. This could lead to
the same 86 vs 47 percent discrepancy that is so widely cited.

Let's have a look:

http://www.movingtargetzine.com/article/chinese-whispers-female-cyclists-killed-by-hgvlgvs-in-london-1999-2004
cites TfL: "from 1999 - May 2004:
87 deaths of cyclists of which 21 were female, 66 male Of those 21 females an astonishing 18 (85%) were killed by HGV drivers. Another 28 of the males (around 50%) were also killed by
HGVs."

So, many more dead men than women, and more dead men killed by lorries (28) than women killed by lorries (21). Of course, to conclude anything from that alone is wrong again, because we need to know the proportion of male vs female cyclists in traffic, and see if the above ratio differs from that.

The Independent had the best article about the issue that I've read, available here:
http://motoring.independent.co.uk/comment/article2413395.ece

This says about the male:female cyclist ratio that "[w]hile it was about 73:27 at the start of the decade, statistics from TfL show that it had moved to about 60:40 by 2005."

So compare the numbers (m:f):
Killed by lorry: 28:21 = 1.3
Proportion of cyclists: between 70:30 = 2.3 and 60:40 = 1.5

So it _does_ seem that women are _slightly_ more likely to be killed by a lorry than men, but this difference is small (1.3 vs anything between 1.5-2.3), maybe not even statistically significant, if you compare 1.3 to 1.5. The statistics about male vs female cyclist proportion is probably not very accurate, and the numbers of killed cyclists are (fortunately!) quite small for statistical standards, both of which mean that the difference could well be by chance. In any case, the difference is much smaller than the almost twofold diffence suggested by the "86 vs 47" comparison.

(2) "Men are safer cyclists":

(m:f): Killed: 66:21 = 3.14
Proportion of cyclists: between 70:30 = 2.3 and 60:40 = 1.5

So men are really more likely to be killed than women. Again, the difference is not huge, and the sample size is small, so this is not too meaningful, but the difference here is greater and the sample size is greater than for the "killed by lorry" data, so if you believe from the data above that women are more likely to be killed by a lorry you should definitely believe that men are more likely to be killed in the first place.

So whatever you want to do as a woman, you do not want to unequivocally "ride like a man", as the velorution blog had in its title.

*** Conclusions ***
Of course, taken together, the data above do say something we should care about. Here's what I would say we can conclude from them, and what LCC should do about it:

(1) Lorries are dangerous. They are overrepresented as a cause of cyclist death _both_ for women _and_ for men (since they make up nowhere near even 50 percent of the traffic).
This is no secret. LCC already do stress this point, and we should continue to stress this point. Fitting extra mirrors and pushing cyclist training are the way to go, as is the rethinking of ASLs and especially lefthand feeder lanes. Also, emphasize that the classic left hook with lorries
would most likely not diminish with the presence of segregated cycle lanes, on the contrary. Emphasize that this means that cycle training and driver education are much more
helpful than putting in cycle lanes, segregated or not.

(2) The safety record for men and women cyclists is quite similar, but it is slightly better for women. So if anything, men should ride more like women, but I would not say the data warrant making that recommendation. Besides, there are many differences between the riding styles of men and women, and we need extra information about which aspects of each style are worthy to emulate (we have some such information, and cycle training incorporates the insights, but it is not in the data above).

(3) While the overall safety record of men and women is similar, there could to be a slight difference in what types of vehicles kill them. This difference is nowhere near as big as 2:1, which is how many people read the 84:47 numbers. Under the assumption that this difference is real at all, it would make sense to target advice that prevents cyclist-lorry collisions more heavily at women *and* to target advice to prevent other types of collisions more heavily at men. Note the *and*. However, we don't know whether the difference is real, and since it is very likely that the difference isn't real, we should not waste valuable resources on ensuring that men and women are targeted differently.

(4) We cannot conclude that jumping red lights makes you safer. Even the basic assumption doesn't hold (men safer than women). Jumping red lights might conceivably get you out of the path of the bus into the path of a different vehicle crossing at speed. I am not arguing that it does, but the data would match this pattern. However, one good thing about the media bollocks in my view is that it spreads the notion that at least some red light jumping cyclists are
motivated by safety concerns rather than by aggressiveness. This is another point LCC might want to underline.