Cycling is safer than you think (but not as safe as it should be)

Image by Wolfgang Staudt

Last week there was a tragic and fatal bike accident here in Halifax.  As avid road cyclists, these sorts of accidents always hit home for my wife and I.  Even moreso in this case, as the cyclist’s description (an elementary-school teacher and cycling enthusiast in her early 30’s) is also an apt description for my wife.

Although the cause of the crash is still unclear (the cyclist was hit by a truck turning right, although no word yet on whether anyone was at fault), these sorts of accidents drive home the fact that riding a bike can, at times, be a dangerous activity.  And so, I thought this would be a good time to revisit just how dangerous cycling is, when compared to other modes of transportation.

The most useful information that I’ve encountered on this topic is from a paper in Environmental Health Perspectives which examines whether the benefits of increased cycling (increased physical activity) outweigh the risks (both in terms of accidents and exposure to pollutants for individual cyclists).  To calculate these numbers, the authors examine changes in mortality at both the population level, and for individual cyclists, if 12.5% of current short car trips in the Netherlands were to be performed by cycling instead.

So, what did they find?

The authors report that for most adults, the risk of death when cycling is about 4.3x higher than if the same trip were being made by car (YIKES!). However, we’ve got to remember that commuters not only pose a risk to themselves – they also post a risk to other road users.  And if you’re going to be hit by a vehicle, a Cervelo is going to do you a lot less harm than a Corolla!  There is a reason why you don’t hear about out-of-control cyclists taking out a swath of pedestrians.  So with an increase in the number of trips made by bike, the increased mortality among cyclists due to traffic accidents is offset by the reduced mortality among the general population who would be less likely to be run over crossing the street (interestingly, if it were high risk young drivers who were to switch from driving to cycling, it would actually save lives!).

Now while the risk of being in an accident is higher for cyclists, it must be remembered that they are also likely to be getting increased levels of health promoting physical activity, and substantially reducing their volume of sedentary time.  In fact, the risk of death due to physical inactivity among active commuters is estimated to be 10-50% lower than in non-active commuters – a pretty substantial health benefit!

So will cycling to work make your life longer or shorter?  On average, the risk due to car accidents will reduce your life expectancy by just 5-9 days.   Being exposed to air pollution during your commute could cost you another 8-40 days.  But the physical activity in your commute would actually increase your life expectancy by up to 14 months! Overall, the health benefits of active commuting by bike are 9 times greater than the risks!

Lest that you think that this is only true in the cycling utopia that is the Netherlands, similar studies have also suggested that the benefits of cycling outweigh the dangers in countries ranging from Spain to India and the UK.  Just this week it was reported that after 8.75 million trips covering more than 14 million miles, there has yet to be a single fatality associated with the new Citi bike-share program in New York City (there have been only 100 reported accidents so far, and only 25 of those warranted a trip to the emergency room).  When you consider that the people most likely to use a bike-share program are tourists and other individuals who don’t spend a lot of time on a bike, those results are very heartening.  Especially when you take into account the many failings of urban cycling in North America (see videos below).

What’s the take-home message?

Cycling is obviously more dangerous that it should be, something which needs desperately to be addressed.  But if you decide to commute by bicycle on a regular basis, you are far more likely to improve your health and prolong your life via increased physical activity than you are to shorten your life by getting involved in an accident.  It is interesting and extremely important to note that the number of cyclists on the road is inversely related to the number of car/bike collisions  – so the more of us that get out on the roads, the less likely we are to get in an accident.

And if you do choose to cycle more regularly (which I definitely think you should!), please wear a helmet and obey traffic laws – especially stop signs.  Those two factors alone will go a long way to preventing some cycling related deaths.

Today’s post is an update from a post published on Obesity Panacea in September of 2010.


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6 Responses to Cycling is safer than you think (but not as safe as it should be)

  1. Roberta says:

    Good article, Travis. I’d also point out that cycling education could be very valuable in improving safety. Some defensive cycling techniques are counter-intuitive – such as riding further to the left, not the right and riding at least 6-8 feet away from parked cars. These need to be taught and practiced. Other very dangerous techniques “seem” safe – like staying far to the right at all times, passing vehicles on the right even if they might be turning, riding on the sidewalk and riding against traffic. European cycling countries have extensive education programs starting in elementary school. Educational efforts in North America are far behind. I encourage people to take a Can-Bike course, or even to read about ‘Cycling Savvy’, an American road skills course, to learn techniques that can improve their riding experience.

  2. Charles A-M says:

    Interesting comparisons.

    Two comments:

    – CitiBike, which uses the same technology as Bixi, measures distance traveled based on the distance between the station where the bike was picked up and the station where the bike was dropped off. The actual mileage is probably much higher; I know when I ride a bixi it’s to run some errands at lunchtime and I often pick up and drop off the bike at the same station (or one that doesn’t reflect the distance I actually traveled on that trip)

    – It’s widely regarded that young (especially male) drivers are at a higher risk of being in a collision. Traditionally, most youth get their license as early as they can, but youth today (urban millenials) have been getting theirs later and later, or not at all. I wonder how much of the risk differential is influenced by the fact that the driver is young in comparison to the fact that the driver is new (therefore has less driving experience). FWIW insurance companies’ threshold is age only, not how long you’ve had your license, and hopefully they base their practices based on stats.

    • Travis says:

      Excellent comments, as always, Charles.

      This is my bias, but I tend to think that age and experience have independent effects on driving. This is totally based on pop psychology (and therefore potentially way off base), but I seem to remember younger people, having less impulse control than older individuals. Which could lead to poor decision making (e.g. trying to pass when there’s not enough time/space).

      However, I think there is also a learning curve in terms of motor skills and decision making, which would be an issue for all new drivers. It also seems that older drivers tend to self-regulate (e.g. avoiding driving in poor conditions, etc) in a way that younger drivers may not. These are sweeping generalizations of course, but that’s why I would hypothesize that any new driver is likely at increased risk of an accident, but especially so for new young drivers.

  3. Travis says:

    I agree that defensive cycling is counter-intuitive – I often need to remind myself to move further to the left to stay well clear or parked cars (although I’ve also had my arm brushed by the mirror of a passing bus that refused to move over enough… sometimes defensive cycling feels like a damned if you do, damned if you don’t situation). I would love it if both cyclists and drivers were more educated here in North America, myself included!

  4. Pingback: Cycling is safer than you think (but not as safe as it should be)Sports News Stories | Sports News Stories

  5. Brandon says:

    Nice writeup, but I do have a small nit to pick:

    … please wear a helmet and obey traffic laws – especially stop signs. Those two factors alone will go a long way to preventing some cycling related deaths.

    I think you’d have a tough time showing this via actual evidence. Personally, I’m inclined to always wear a helmet, but the data on the matter is incredibly shoddy and often defaults to showing a rider as not wearing a helmet when it’s simply not listed on the accident report. Many accidents are of such a nature that the helmet just isn’t going to do much to save the riders. They do, of course, improve safety by a nontrival amount, but that’d likely be the case for pedestrians and drivers as well, yet few advocate helmets for driving.

    On the question of stop signs, the data is even less clear, but I think most people that ride with any regularity can confirm from experience that there’s little danger from the proverbial Idaho stop. No one should outright run stop signs, but slowing to a walking pace, getting tall, and surveying for traffic provides a pretty high degree of safety. Track stands are also an option for the skilled, although they’re technically illegal in some locales that require putting a foot down at each stop sign.

    At present, I don’t see much evidence that laws regarding cycling are constructed with the safety of the cyclist in mind near as much as the convenience of the driver.