# Are you more likely to suffer a head injury walking than cycling?

An Olympic cyclist, Chris Boardman, recently made the claim that people are more likely to suffer a head injury walking, rather than cycling.

[...] cycling is safe. You would have to wear a helmet walking, you are statistically more likely to have a head injury walking.

Source: BBC News

Is there any evidence for this?

• I have worked for a long time in surgery. The injuries among cyclists were not only more frequent, but also more serious. Apart from the additional exposure to motor vehicles. – bummi Apr 28 '13 at 16:47
• @bummi: Working in surgery would not expose you to a statistically significant sampling. You would only be exposed to injuries sufficiently serious to warrant surgery. Your personal sample size may be relevant to a claim of "Walking causes more serious injuries than cycling," but that was not the claim. – Flimzy Apr 29 '13 at 0:44
• my guess would be that maybe there are more total head injuries walking than cycling, just because people spend much more time walking than cycling. if you look at injuries per hour walked vs cycled, or probably even injuries per kilometer walked vs cycled, you'd probably find that cycling is more dangerous. but i don't have any data so i'll leave it here as a comment. :) – Kip May 2 '13 at 12:33

### 1. Caveat

This is going to be an unsatisfactory answer, for the following reasons:

1. Boardman's claim is ambiguous: how are we to interpret the you in "you are statistically more likely to have a head injury walking"? A statistically average person in the country, considered over some period of time such as a year? Someone considering making a particular journey and wondering which mode is riskier? Or someone else?

2. I could find no official statistics which break down casualties by location of injury, so we're going to have to put up with "killed" and "killed or injured" as proxies for head injury figures in what follows.

3. These statistics seem likely to undercount injuries to pedestrians (relative to cyclists), because they only include road casualties that have been reported to the police. Many (perhaps most) injuries to pedestrians will not be reported as road casualties (either because they did not occur on a road, or because no vehicle was involved).

(No doubt you can think of more problems. Point them out in the comments, but please see if you can find relevant statistics. The difficulty here is not in spotting biases, but in finding data to address them.)

### 2. Absolute figures

In Great Britain in 2012, the average person was about 3.5 times as likely to be killed in a road traffic accident when walking as when cycling (and about 1.8 times as likely to be killed or seriously injured).

                          2008    2009    2010    2011    2012
PEDESTRIANS
==============================================================
Killed                     572     500     405     453     420
Seriously injured        6,070   5,545   5,200   5,454   5,559
KSI                      6,642   6,045   5,605   5,907   5,979
Slightly injured        21,840  20,842  20,240  20,291  19,239
All casualties          28,482  26,887  25,845  26,198  25,218
==============================================================

PEDAL CYCLISTS
==============================================================
Killed                     115     104     111     107     118
Seriously injured        2,450   2,606   2,660   3,085   3,222
KSI                      2,565   2,710   2,771   3,192   3,340
Slightly injured        13,732  14,354  14,414  16,023  15,751
All casualties          16,297  17,064  17,185  19,215  19,091
==============================================================


### 3. By distance

In Great Britain in 2012, per kilometre travelled, the average person was about as likely to be killed in a road traffic accident when walking as when cycling, but about half as likely to be seriously injured.

                          2008    2009    2010    2011    2012
==============================================================
Kilometres walked          311     316     294     301     290
Kilometres cycled           68      73      68      79      85
==============================================================

PEDESTRIANS (per 100 million kilometres walked)
==============================================================
Killed                     3.0     2.6     2.2     2.5     2.4
Seriously injured         31.8    28.6    28.8    29.5    31.2
KSI                       34.8    31.2    31.0    31.9    33.5
Slightly injured         114.4   107.6   112.0   109.7   107.9
All casualties           149.2   138.8   143.0   141.7   141.5
==============================================================

PEDAL CYCLISTS  (per 100 million kilometres cycled)
==============================================================
Killed                     2.8     2.3     2.6     2.2     2.3
Seriously injured         59.0    57.9    63.5    63.9    61.9
KSI                       61.8    60.2    66.1    66.2    64.2
Slightly injured         330.9   319.1   343.9   332.1   302.8
All casualties           392.7   379.4   410.0   398.3   367.0
==============================================================


### 4. Summary

Boardman is likely correct when considering a statistically average person in the country, and likely wrong when considering which transport mode to use for a particular journey. But I think his broader point is a fair one: the difference in casualty rates between the two modes of transport is not big enough to justify treating them differently in law.

• Please provide a reference for "the difference in casualty rates between the two modes of transport is not big enough to justify treating them differently in law." – user5582 Jul 26 '13 at 19:12
• @Sancho: see the start of the sentence (which you cut in your quote). – Gareth Rees Jul 26 '13 at 19:21
• That's not a reference. – user5582 Jul 26 '13 at 19:25
• @Sancho: sentence starts "But I think" which indicates it is my personal opinion. – Gareth Rees Jul 26 '13 at 20:11
• Okay. That's cool. – user5582 Jul 26 '13 at 20:30