Serious and fatal road casualties by mode, London 2012 (%). Source: TfL

I hear frequent claims that the dangers associated with cycling on roads are exaggerated. That goes against my intuition because I always feel much more vulnerable when cycling than I do when driving. My perception – and that of many others I speak to – is that cycling on roads is bloody dangerous.

New data released by Transport for London suggests my intuition is consistent with reality. A total of 671 cyclists in Greater London suffered a serious or fatal injury (a further 3,942 suffered minor injuries) over the course of 2012. That’s more in absolute terms than the corresponding total for cars, taxis, buses and trucks combined. It’s even bigger than the total for motor bikes/scooters.

Pedestrians are involved in a larger number of serious and fatal accidents but virtually everyone in Greater London is a pedestrian at some time or another in the course of a year. Cycling however accounts for less than 5% of road trips (fn 1) but, as shown in the first exhibit, for an extraordinary 22% of all serious and fatal accidents.

The second exhibit (via (Drawing) Rings Around the World) shows the trend in cycling casualties in London over the 33 years from 1979 to 2012. It’s evident they increased markedly over the last ten years, accelerating from around 8% of all serious and fatal injuries in 2003 to the current figure of 22%.

That of course correlates with the big increase in cycling over the last ten years in London, so it’s no surprise the absolute number of casualties increased. But it’s not so easy to explain the enormous increase in cyclist’s share of casualties.

It suggests that the “safety in numbers” effect for cycling is either a myth or, more likely, it’s a great deal more complex than is usually assumed.

It might be that the effect isn’t linear or maybe it only applies beyond a certain critical mass. Cycling might need to have a much larger mode share than 2% before the “safety in numbers” effect starts to have a discernible impact. Perhaps the curve starts slowly and only accelerates steeply when the mode share is very large.

Or it might be the effect only applies in cities where the majority of drivers also bicycle from time to time and hence empathise with cyclists. Another explanation could be confusion about causation – cities with large numbers of cyclists are also likely to have infrastructure and regulations that support cycling and “tame” motorists.

London is a more relevant example for Australia than Dutch or Danish cities because cycling is still a residual mode in the UK like it is here. Unfortunately I don’t have any data on exposure – kms or hours of cycle travel – to get a good sense of the odds of suffering a serious or fatal injury in London while cycling.

However 14 deaths and 657 serious injuries in a single year is way too many and is bound to have a serious deterrent effect on prospective cyclists (you might remember the tragic death of a cyclist during the London Olympics). London and Australian cities need to invest in infrastructure and foster a supportive road culture through regulation and education aimed primarily at truck, bus and car drivers.

Of course the risks of injury associated with cycling have to be balanced against the health benefits. Here in Australia I expect I’m still better off cycling in traffic – notwithstanding the risks – if I don’t exercise in any other way. I choose to cycle on roads but if I ever find it too threatening I, like most everyone else, have other options for exercise, not least simply walking places.

Update 1 (10 am 8 July): Boris Johnson’s “near-death experience while cycling.

Update 2 (10 am 8 July): The risk associated with bikeshare is much lower.

% all serious and fatal casualties suffered by cyclists, London 1979-2012. Source: (Drawing) Rings Around the World


(fn 1) If all modes are counted, cycling’s mode share is around 2%