Aug 21, 2013

Is cycling more dangerous than driving?

There's a curiously persistent view that cycling on roads isn't an especially dangerous activity. The best evidence however supports most rider's intuition - cycling with traffic is bloody dangerous

Alan Davies — Editor of The Urbanist

Alan Davies

Editor of The Urbanist

Bike/car fatality and injury risk for cyclists vs car occupants in Sydney (based on Garrard et al)

I’ve previously questioned the surprisingly common view that cycling on roads isn’t dangerous. In this article, Does cycling on roads put your health at risk?, I pointed to data released by Transport for London which suggests cycling in London is more dangerous than any other mode except motor cycling.

In another article, Do Coroners sometimes go too far?, I cited a study that calculated the risk for Australian children of travelling to school by bus relative to other modes. When exposure is accounted for (i.e. kms of travel), taking the bus is 1.4 times safer in terms of the risk of death or serious injury than being driven; 4.4 times safer than walking; and an extraordinary 55 times safer than cycling.

An economic appraisal of the proposed Inner Sydney Regional Bicycle Network prepared by AECOM for the City of Sydney states that an increase in cycling at the expense of other modes would increase the total cost of accidents to the community.

Now a reader has drawn my attention to a more recent Australian study, Cycling injuries in Australia: road safety’s blind spot?, by J Garrard, S Greaves and A Ellison.

They looked at Police data on road crashes in Sydney over a four year period by mode and compared these against distance travelled (see exhibit). They estimate the relative risk of a fatality on a bicycle in Sydney was around 11-19 times higher than in a car. The researchers also looked at Police-generated crash data for Melbourne in 2007-08 and found the fatality risk for a cyclist travelling the same distance on the roads as a car driver or passenger was four and a half times that of a car occupant.

There’s a large range in these estimates because the number of cyclist fatalities is small i.e. between 8 and 10 p.a. over four years in Sydney (compared to annual counts of 164-185 for car occupants) and 4 in Melbourne in 2007-08 (96 for car occupants). However in all cases the risk of fatality is much higher for cyclists.

The researchers also looked at injuries (where the numbers were much larger). The risk of suffering an injury in Sydney was 13-15 times higher for a cyclist, although injury severity isn’t identified in NSW, so some relatively minor injuries will be included. Fortunately the Victorian data does discriminate by severity and the results are broadly similar; the risk of a serious injury in 2008-09 was 12.9 times greater for a cyclist than a car driver. (1)

In the case of Melbourne, the researchers also had access to hospital data on serious injuries suffered by cyclists and car travellers in 2007-08. While the numbers were essentially the same as the Police data in the case of cars, there were two and a half times as many serious cyclist injuries compared to the police data base, indicating many hospital presentations are the result of off-road incidents. If these cases are included, the relative risk of cycling compared with driving was 34 times higher in Melbourne.

The researchers go on to point out that cyclist injuries increased 109% in Melbourne between 2000 and 2008, and conclude that:

While road safety counter-measures have undoubtedly led to a safer operating environment for vehicle occupants, the (arguably) car-centric nature of many of these measures has in fact done little to improve cyclist safety. Cyclists appear to be over-represented in terms of fatalities and serious injuries relative to their exposure to traffic, but under-represented in interventions aimed at reducing traffic fatalities and injuries.

Caution is needed in interpreting the numbers because of the limitations of the data e.g. it’s collected by staff whose main priority at the time of the incident isn’t record keeping. Much more caution is needed though when interpreting fatality data presented by the Qld Transport Department to the Parliamentary Inquiry Into Cycling Issues. The Department simply presented fatality data for various countries by dividing by population.

Update: another reader commenting on a different article has cited this study, Injuries to pedal cyclists on New Zealand roads, 1988-2007. She says it shows “the average number of serious (AIS>2) injuries per million hours spent travelling in 2003-07 was 6.2 for cyclists, 1.0 for pedestrians, and 0.8 for car/van drivers.”


  1. It’s sometimes argued that using kilometres of travel can give a misleading impression because car trips tend to be longer than bicycle trips. In Melbourne, for example, the average weekday trip by car is 11.7 km compared to 5.3 km by bicycle. The average duration of travel however is similar: 20.5 minutes for cars versus 22.4 minutes for bicycles. (Note though that in their study for the City of Sydney, AECOM assumed an average 9 km trip distance for cycling). Even if that proposition is accepted, using time or the number of trips as the metric only halves the relative risk of bicycle travel in Melbourne in 2007-08. A cyclist is still around twice as likely to die and around six times more likely to suffer a serious injury than a driver if he or she cycles on the road. In any event, this argument only holds when the same trip is compared (as is the case here). On average, however, cyclists make fewer trips than drivers, so over the course of a year, total kilometres and hours spent on the road by all cyclists will be considerably lower than the corresponding figure for all drivers.


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21 thoughts on “Is cycling more dangerous than driving?

  1. peter mackenzie

    With all road-use, we have an very incomplete approach to risk data. With bicycling (as with other road-users) the levels of risk are far higher than crash stats will show, so the level of safety is vastly different than shown by crash rates.

    Using a variety of sources, we know that near-misses occur in large numbers and as shown by Marilyn Johnson from Mon ash Uni, evasion of motorists errors separate safe escape from crashes. The converse would happen (ie where motorists evade the errors of cyclists).

    Some cyclists contribute to the the additional risks, and we know that much risk is created/contributed to by motor vehicle drivers.

    There is no easy or quick fix, but cyclists can take actions to lessen risks through defensive approaches, including enhancing visibility.

    The greater problem though, is that in regard to motor vehicle drivers, the safety approaches (not yet what could be called a system) are still incomplete, flawed and inadequate.

    Cyclists could do more to demand improvements but I would be wary of backlash from motorists who already don’t want you “lycrasites” on “my road”.

  2. Alan Davies

    Bojun Bjorkman-Chiswell #18:

    When you’re able to support your off-the-top-of-my-head opinion with the sort of considered research that Garrard et al have put into this issue you might be in a position to label their results as “laughable”.

    I’ve not heard anyone use the term “epidemic”, but Garrard et al report there were 1,075 bicycle-related serious injuries on the Victorian hospital admissions database in 2007-08. That’s not a trivial number and suggests that improving safety for cycling should be a priority.

    Cycling is only one of many ways that are needed to tackle sedentary lifestyle diseases, but it won’t make a significantly bigger contribution unless and until prospective riders perceive it’s safer.

  3. Dylan Nicholson

    I don’t think that’s a fair and/or productive comment Bojun. Studies consistently show that one of the main reasons more people don’t use bikes for commuting etc. is because of fears for safety. While I had previously disputed that these fears were well grounded in statistics, it seems that unfortunately for most Australian cities they’re not completely irrational. The statistics that do exist should be more than enough to convince governments of the need to make serious efforts to improve the safety of our roads for cyclists, which is probably the single biggest thing that can be done to encourage more people out of cars and onto bikes.
    And it’s obviously not completely sensible to suggest the only alternative to more cycling is continued sedentary/inactive lifestyles – there are less risky ways of getting exercise that people could and do choose. Cycling obviously has a number of advantages of many of those, but as long as it’s perceived as being unsafe, only the less risk-averse among us will be likely to take it up.

  4. Bojun Bjrokman-Chiswell

    A laughable set of results and article completely removed from reality. Reality: we have a sedentary life-style disease, obesity, childhood asthma, environmental cancers epidemic not a bicycle road-kill epidemic.

  5. cbp

    I don’t think it’s a question of finding your post anti-cycling, as I think most people are aware that you are generally pro-cycling. The problem is that the correct answer to the question “is cycling more dangerous than driving” depends on who’s asking.

    If we simply looked at raw data, we may find that many deaths occur due to falls in the bath tubs. In fact, more people die in bath tubs than in cars. But are bath tubs more dangerous cars? Well, the statistics of falls in bath tubs are massively skewed by the elderly and disabled. For the able-bodied, bath tubs pose almost no threat. The context of the question is important.

  6. Alan Davies

    Frank Krygowski #12, #13:

    For the record, I’m certainly not advocating that because cycling on roads is more dangerous than driving, travellers shouldn’t cycle! As you say, the benefits have to be taken into account too. I didn’t realise it might be interpreted as anti-cycling (in fact I’m a little surprised).

    But as to your last sentence though, the article is not seeking “to discourage cycling”. Safety is the key worry identified by existing cyclists and, importantly, those who’re deterred. People don’t tend to think “Oh, only 30 deaths, no worries then”. The answer is to improve safety – understanding that safety is an issue is part of the process of improvement.

  7. Dylan Nicholson

    Frank, good points (I’ll leave it to others to double-check your facts – not too sure about the meteorite claim!) though I’d also say it’s not just fatalities we should be worried about – as a cyclist I very much care about the risk of any injury that means a hospital visit and an period of enforced rest & recovery (and certainly any injury that entails serious permanent damage), and it would seem such injuries are quite a bit more likely while cycling vs driving. But yes, for me (and I’d think a large percentage of the population) the benefits still clearly outweigh the risks, and there’s still a undeniable argument for encouraging more people to ride more (as a substitute for any non-physical activity, including driving). OTOH I don’t think there’s any justifiable argument for encouraging people to drive more, no matter how safe it might be for the driver.

  8. Dylan Nicholson

    cbp, I’d never recommended *against* cycling, but I would at least now confirm when suggesting that cycling would be a good option for someone that they know there is a safety risk and should start out using bike-paths, quiet streets and even foot-paths to build up their skill level.

  9. Frank Krygowski

    Sorry to follow up on my own post, but I see that one of the papers cited in the article, _Cycling injuries in Australia: road safety’s blind spot?_, by J Garrard, S Greaves and A Ellison, contains data confirming one of my points. On page 40, it lists bicycling’s fatality rate for the Melbourne area as 1.18 fatalities per 100,000,000 km. That works out to about 85 MILLION kilometers, or 53 MILLION miles cycled between fatalities!

    This is, in fact, a much higher level of safety than found in many other studies of other countries. It appears that Melbourne cycling is even less dangerous than in many other jurisdictions around the globe. There can be little doubt that the health and environmental benefits of cycling in Melbourne are far greater than the tiny risks.

  10. Frank Krygowski

    The author Mr. Davies seems to be confused about the fundamental question. “Is cycling dangerous?” is not the same question as “Is cycling more dangerous per mile than riding in a car?”; yet he treats those questions as equivalent.

    First, one should understand that with bike or car fatalities per mile, one is evaluating infinitesmals. Studies in many countries (including Australia) have concluded that there are well over ten million miles ridden on bikes between fatalities. It should be clear that worrying about one’s dying on a given bike trip is akin to worrying about being struck by meteorites. That risk, too, may be worse on a bike than in a car, but it is still negligible.

    Second, as others have said, a car vs. bike comparison should at least exclude long distance and super-safe motorway travel that’s banned for bikes. When the comparison is made for truly comparable trips, the risk per mile is much closer.

    But third and most important, the proper evaluation of danger should be risk vs. benefit. The risks vs. benefits of cycling have been evaluated in several peer-reviewed studies, and in every case, benefits far outweighed risks. The lowest benefit-to-risk ratio found in four different studies was 7:1, the highest 88:1. In every case, cycling was literally found to be safer than NOT cycling! How can it then be called “dangerous”?

    In a society famous for lack of exercise, obesity, and the health problems and fatalities that result, it makes no sense to pretend bicycling is dangerous. 45000 Australians die of cardiac disease annually, and 9000 due to strokes, with many of those deaths preventable through moderate physical activity such as cycling.

    Should we discourage cycling because of it’s three dozen deaths per year? Nonsense!

  11. Socrates


    If you look up the Austroads Guide to Road Design, you will find that roads are designed for motorcycle safety where practical. In particular, design treatments for armco steel crash barriers have been changed in recent years to reduce hazard for cyclists. Panels have been added along the ground level part of the barriers to assist motorcyclists to slide along the edge of such barriers, and not have their legs caught in the barrier support posts. This reduces impact severity for motorcyclists.

  12. Socrates


    Thanks for running the topic. I think the reason for the discrepancy between cycling fatali figures can be explained as follows. It relates to accident reporting. Many minor car accodents are not reported to police. Car accidents that are serious enough to injure the occupants are usualy reported, for insurance reasons, among others.

    The situation is different for cyclists. There is less motivation for reporting of cycle accidents to police for insurance or other purpose. At the same time a minor collision with a car might easily injure a cyclist enough to require medical treatment. That treatment will be recorded by the hospital, but often not by the police.

  13. Tom the first and best


    Not only are there health benefits but there are safety for others benefits. Cyclists kill and injure far fewer non-cyclists and other cyclists that motorists kill and injury non-motorists and other motorists.

    Similarly, do we want the risk takers to take risks with a few kg of bike of 1,000-2,000 kg of car?

  14. Nik Dow

    Not all cyclists ride in the same way.

    In The Netherlands, you hardly ever see a cyclist wearing a helmet, but 15% of head injury presentations at hospitals there were wearing one when they crashed. Australian academics would conclude that helmets are incredibly dangerous and should be banned. But I digress.

    The reason helmeted riders are so over represented in The Netherlands hospitcal head injury presentations is that they are racing (sport) riders who ride a lot faster than utility riders.

    So in Australia “cycling” is more dangerous than driving. As Steve Bennett hints, your own risk depends on how you ride. According to last year’s study (joint MUARC and Alfred Hospital) the relative risk of a head injury was 5:1 for speeds over 30 vs under 20km/h.

    So to what extent is “cycling dangerous” per se, compared with “you can cycle in a dangerous fashion”? Australian cycling contains a high proportion of recreational and sport cycling compared to countries where more people ride for transport. Perhaps this contributes to cycling being “more dangerous”.

  15. cbp

    The arguments I’ve heard usually also include reference to the health benefits of cycling outweighing the dangers, i.e. for every cycling fatality there is also someone who doesn’t die of heart attack in middle age due to inactivity.

    Secondly, there is also the question of cyclists being greater risk-takers. Cycling, like motorcycling, has a greater proportion of adventurous males compared to driving.

    Thirdly, government initiatives to promote cycling has two sides – better infrastructure, but also stricter law enforcement. Drink-driving is comparatively heavily enforced compared to drink-cycling. 40km/h is dangerously fast on a bike in many situations, but a lower speed limit is rarely (never) enforced.

    So yes, cycling may be dangerous. But without further data, can we go ahead and recommend against cycling to our female, risk-averse friends on the basis that it will be dangerous for them?

  16. Charlie Maigne

    @Harry Becher

    Do you have any stats to support your proposition, like a comparison of fatalities per trip? I can’t seem to find any.

    Besides, a big chunk (over 40%) of motorcycle accidents are single-vehicle, and I suspect a good proportion of those were during recreational trips. For accidents involving a motorcycle and another vehicle, I think it’s something like 43% where the rider’s at fault.

    That means that over 50% of motorcycle accidents are down to rider error, and there’s not a lot you can do about that. Certainly any attempt will be resented and opposed by the people you’re trying to help (myself included).

    As for the rest (multi-vehicle accidents where the rider is not at fault) there’ve been numerous awareness campaigns and things like that. I’m not sure what more you think can be done.

    At the end of the day, motorcyclists can rely on the speed and manoeuvrability of their vehicle to avoid danger on the road. Cyclists have no such luxury, so the money’s probably better spent there.

  17. Alan Davies

    Steve Bennett #3, Dylan Nicholson #4:

    The authors used both data bases to allow for those kinds of objections. However the hospital one has value as it includes bicycle paths (e.g. Yarra Trail). I’ve known plenty of riders who’ve incorporated a bike path in their commutes for almost all or part of their journey.

  18. Dylan Nicholson

    Steve, more than just ‘iffy’ – I’d say it’s about as useful as comparing the safety of hang-gliding vs tying your shoelaces, or any recreational vs utility activity.
    Really the only interesting comparison to me is between trips that are currently made by car but reasonably could be made by bicycle instead (e.g., utility trips not involving distances over 20km, or carrying large loads), and those actually made by bicycle. Unless the majority of serious accidents involving motorists are occurring during such trips (which seems unlikely), or the majority of serious accidents involving bicycles are occurring during non-utility or unusually long-distance trips (possible but I doubt it) it seems hard to deny that as it is currently, you’re safer travelling by car than by bike. Still I think it warrants further investigation.

  19. Steve Bennett

    >…many hospital presentations are the result of off-road incidents. If these cases are included, the relative risk of cycling compared with driving was 34 times higher in Melbourne.

    That sounds like an iffy comparison, because you’d be comparing mountain biking and recreational riding against non-recreational car driving.

    One thing I’d love to know: how much can cyclists reduce their risk? Let’s say cycling is on average 20 times more dangerous than driving. Can a really sensible, cautious cyclist reduce that level for themselves to 10 times? 5? 1?

  20. Dylan Nicholson

    Sigh…I can only hope the meme, inaccurate as it may be, survives until it is actually true, because the only way cycling will ever be truly safe is once enough people do it that a) governments realise they have no choice but to spend more on better infrastructure, introduce and properly enforce policies that improve safety (speed limits, passing distances, liability laws etc.) and ensure drivers are better educated and more aware of other road users through stricter testing/advertising campaigns etc. etc. and b) most drivers are at least occasional cyclists too so are more inclined to be aware of how to share the roads safely.

    In the mean time I’ll just have to console myself with the knowledge that probably the single biggest risk of my premature death occurs during an activity I love doing…

  21. Harry Becher

    Millions of dollars are spent every year on cyclist safety, mostly through dedicated cycle lanes and tracks.

    Yet, they are still at far less risk of fatalities than motorcyclists, for whom no money is spent on safety initiatives. We’re constantly being told to share the road with cyclists, yet every year dozens of Australian motorcyclists are killed by motorists who aren’t sharing the road.

    Whilst this doesn’t preclude us as a society from trying to prevent cyclist deaths, the amount of effort is not proportional to the risk; at least, compared to motorcyclists.

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