Tag Archives: risk

Is it really 20 times more dangerous?

I’ve been seeing, more often lately it seems, fairly bold numerical statements about relative bike traffic safety; so to take this one from peopleforbikes for example (my emphasis added): “The problem is particularly glaring here in the United States, where bike injury and fatality rates are roughly 20 times those of the cycling-friendly countries of western Europe“. Continue reading Is it really 20 times more dangerous?

Is Bicycling Safe? Is Bicycling Dangerous?

Short answer: As with all modes of transportation, it entails some danger.

Longer answer: yes, similar to the risk of motoring — perhaps twice as risky. but how to measure? (per mile, per trip?). Bike-MV collisions are currently running 2% of all in AZ. Bicycling represents perhaps 1%, i.e. twice the risk.

For the moment, this is going to be a catch-all for links and related info on the topic. Links:

Good factoid in the article about a bicylist who plead guilty to a felony (thought to be the ONLY one in history) vehicular homicide in a pedestrian death in 2012 in San Francisco:

Some 4,834 cyclists and 59,925 pedestrians were killed by motor vehicles in the United States between 1999 and 2009 (the most recent year for which figures are available), according to the Centers for Disease Control and Prevention. Cyclists killed just 63 pedestrians, or about six a year, during the same time period. — NYTimes

That’s about a thousand-to-one ratio of car-ped to bike-ped pedestrian deaths. Car drivers are more dangerous. That was re-quoted by Carl Alviani‘s article widely disseminated entitled Why Bikes Make Smart People Say Dumb Things:  “After 15 million miles traveled, the Citibike program has still caused not a single fatality for either pedestrians or riders” (stats as of 2014?) he also ; which lays out a good case that bicycling isn’t particularly dangerous to either riders or other road users. The bikeshare stats were sourced to a slate article Not One Person Has Died on an NYC Bike-Share Bike;

Many places have (re)cited data attributed to a company named Failure Analysis Associates, Inc  (now know as Exponent), expressed as # of Fatalities per 1,000,000 Exposure Hours

  • Skydiving 128.71          Snowmobiling .88
  • General Flying 15.58      Motoring .47
  • Motorcycling 8.80      Water skiing .28
  • Scuba Diving 1.98         Bicycling .26
  • Living 1.53                    Airline Flying .15
  • Swimming 1.07           Hunting .08

I have been unable to find any primary sources on this data and how it was produced. Though a relatively recent Grist Magazine article Not pedaling can kill you, Alan Durning  states “The engineering journal Design News published it with little comment in 1993 in an article on a different subject”, and has some further elaboration.

Motorcycling vs. driving an automobile safety per mile can be relativley precisely measured; it runs about 30X more fatality per mile traveled. Compare e.g. Table 1-35: U.S. Vehicle-Miles (e.g. in 2015 , motorcycling is a bit less than 1% compared to all light-vehicle miles; 19.6B vs. 2.1478T; and of course has proportionately many many times the number of fatalities per mile traveled; easily looked up but it’s like 20,000 light-vehicle deaths compared to 5,000 motorcycle)

Take Back the ‘Burbs, Sunset Magazine June 2012 issue;  sidebar titled Is Biking Safe?:

Fear of traffic is one of the top reasons people don’t bike. But, statistically, biking is safer than driving, and wearing a helmet makes it even more so. Here are the annual odds of fatalities for common activities, according to the most recent stats. –Aislyn Greene

  • Motorcycling 1/ 6,141
  • Driving 1/ 11,883
  • Working 1 / 30,735
  • Biking (all) 1 / 68,673
  • Walking 1/ 75,026
  • Swimming 1/ 87,357
  • Biking with helmet 1/ 342,847
  • Flying 1/ 1,476,136
  • riding in a train 1/ 216,475,677

Sources: Bureau of Transportation Statistics, Centers for Disease Control and Prevention, Consumer Reports, Federal Railroad Administration, Insurance Institute for Highway Safety, Motorcycle Industry Council, National Transportation Safety Board, the Outdoor Foundation, U.S. Bureau of Labor Statistics, U.S. Department of Transportation (full article currently available at saferoutespartnership.org site)

Not many clues as to how these numbers were figured.


Continue reading Is Bicycling Safe? Is Bicycling Dangerous?

How Risky is it, Really?

There’s a wonderful book written by author and former journalist David Ropeik that explains risk perception (and MIS-perception) in elemental terms; How Risky is it, Really?.

His explanations go all the way down to the biological and evolutionary level — think adrenalin, amygdala, and the fight/flight response — and it’s all very fascinating. Everyone should read it.

More to the point here, his “confessions” as a former journalist i think go a long way to explain the persistent problems with media stories regarding risk (p. 165):

Before I go on, mea culpa. I was a daily television reporter for 25 years, and most of the things that journalist do that make the world sound like a riskier place than it is, I did…. I regularly played up the dramatic aspects of my stories, emphasizing the negative or the frightening or the controversial, and deemphasizing (or omitting altogether) the aspects that would balance things out of put them in perspective… I never lied… But I did what most journalists do: I made choice that would make my stories more newsworthy, more dramatic , and more likely to attract attention. And that left my views with a distorted and more alarmning view of the world than was actually the case.


In chapter 2, Bounded Rationality, he explains several shortcuts we (everyone) use to determine whether something is safe vs. risky. Among them is how any particular issue is “framed”; this is critical in any sort of news story. Consider the following two statements:

Statement 1; actual quote from an AZ Rep news story on the BSAP:

Last year, 19 bicyclists died and more than 1,500 were injured, according to new Arizona Department of Transportation statistics

Statement 2; re-framed in terms of overall traffic safety

During the study period,  bicyclists accounted for only 1.5% of all traffic collisions, and less than 3% of traffic fatalities, according to Arizona Department of Transportation statistics. This indicates that bicycling is a small part of a very large problem

Which sounds scarier to bicyclists? Which reinforces notions of danger? Is 1,500 injuries (or 19 fatalities) a lot, or a little?

The thirteen Risk Perception Factors

  1. Trust
  2. Risk vs. Benefit
  3. Control
  4. Choice
  5. Is the risk natural or human-made
  6. Pain and suffering
  7. Uncertainty
  8. Catastropihc or chronic
  9. Can it happen to me?
  10. Is the risk new or familiar?
  11. Risks to children
  12. Personification
  13. Fairness

These factors fuel what Ropeik terms the Risk-perception Gap; which leads to poor decisions being made both by individuals and by society.

Free Range Kids

Along the same idea, is so-and-so’s book Free Range Kids, which I am now reading (Jan 2012)