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Posted by on May 29, 2009 in Safety | 7 comments

Traveling in the Realm of Very Big — and Very Small — Numbers

mighk-on-robinsonIn the comments for the post How do we get from here to there? I asked readers to estimate how many miles they’ve biked in what they considered to be a “vehicular cycling” manner, and how many motorist-related crashes they’d experienced in those miles. Here are the results (which are of course not scientific, but still pretty darn impressive):

Fourteen respondents reported a combined 631,000 miles — and average of about 45,000 miles — with only two motorist-related crashes. So that works out to 315,500 miles per crash. Curiously, we had one major outlier who accounted for not only the most miles, but both crashes — and it was none other than Vehicular Cycling Grand Poobah John Forester, with 205,000 miles under his belt. With John’s numbers removed we get 426,000 miles with no crashes.

Also notable is that neither of John’s crashes involved overtaking motorists; one was a left-cross and the other a dooring (!).

Keri reported a crash in a bike lane before taking up vehicular cycling. While I reported 50,000 miles of vehicular cycling, I had another 100,000 miles before that of being a gutter bunny, and still managed to escape without a motorist-caused injury.  ChipSeal reported being right-hooked, but without a crash.  Rodney reported being run off the road a couple times, but we’ll cut him some slack with his mere 4,000 miles of experience.

(Bill Moritz of course did a self-reporting survey of experienced cyclists, but he didn’t ask people to differentiate between their “vehicular cycling” experience and their “other” cycling miles; neither did he ask for crash types.  On the other hand, he had about 2,400 respondents to our 14.)

Let’s play with these numbers a bit to put them into perspective (using the 631,000 miles and two crashes).

If we assume a cyclist travels at about 12 mph (reasonable when you consider urban/suburban cycling and traffic signals) that’s 52,583 hours of cycling; 26,291 hours per crash. 26,291 hours equals right about 3 years of cycling, every day, 24 hours a day.  Assuming a more realistic cycling schedule of one hour per day, 365 days a year, that’s 72 years between crashes.

And how many passing motorists does this involve? (Remember, none of our crashes involved overtaking motorists.) If we were passed by only one car every five minutes, that’s 630,996 passing cars (52,583 X 12). If we were passed once per minute, that’s 3,154,980 passing cars. (For those who do mostly urban cycling, the number is of course much higher than one passing car per minute.  You can do the math; just multiply 3 million by passing cars per minute.)  And gee, not one of those motorists was so incompetent as to hit a cyclist ahead of them on the roadway. If a motorist hits a cyclist from behind (assuming daytime or an adequately lit cyclist at night), he or she must be an exceptionally incompetent driver. (So shall we blame bicyclists for the existence of exceptionally incompetent motorists?)  In recent years cell phone use has become a major concern.  At times it seems that every third or fourth driver has a cell phone at his ear, yet even these compromised drivers manage to avoid hitting us.

In my crash data records for 2003 and 2004 for Metro Orlando, 62 of the 657 daytime crashes involved a roadway cyclist obeying the rules; of those only 22 involved overtaking motorists. What’s more, only two of those overtaking crashes involved incapacitating injuries (none fatal, 11 non-incapacitating, the rest “none, possible or unknown”).  In all but two of the 22 the crash report said it involved “Motorist Misjudged Space,” which is of course one of the key reasons we advocate lane control.

By comparison, there were 158 motorist-at-fault crashes involving daytime sidewalk cyclists, 15 of which involved incapacitating injuries.

In his latest column for Adventure Cycling, John Schubert noted that the US population is 300 million, so a 1-in-a-million event still results in 300 events, and 300 events spread around the Web and TV looks like an epidemic (see also “child abductions”).

Of course, for people who don’t understand risk assessment, these numbers are probably meaningless. Until we can get them out there experiencing it themselves, or at least seeing many others doing it, vehicular cycling and lane control will continue to be perceived as insanely risky.

Lane control does not require any exceptional physical skill.  Indeed it lessens the chances you will need to employ any exceptional bike-handling skills.  It is a choice one makes.  If you can ride a bike, you can do it.

7 Comments

  1. Mighk quoting John Shubert: In his latest column for Adventure Cycling, John Schubert noted that the US population is 300 million, so a 1-in-a-million event still results in 300 events, and 300 events spread around the Web and TV looks like an epidemic (see also “child abductions”).

    So true — assumed risk is inflated when there is no analysis of the events or the numbers …

    Our media does a horrible job of conveying risk or doing any risk analysis when reporting on traffic “accidents” (better to use the word “crashes”). Tom Vanderbilt wrote an excellent article on Traffic crash reporting, where analysis was done on the media reporting of car crashes. Out of 473 nationally reviewed reports:

    Only 1.3% of the reports included information about the weather at the time of the crash

    Only 1.3% of the time was the speed limit mentioned

    Only 17% of the time was the estimated speed of the vehicles involved reported

    Only 22% of the time was seatbelt usage mentioned

    Almost half the time, the time of the day was not mentioned

    Given that all of these are significant factors to help analyze (safe) driving circumstances, how could we ever get a good handle on risk if it goes unreported most of the time?

    Mighk, thanks for applying some analysis to the numbers. I think it becomes clear that the public has been mislead about the risks of street cycling ……

    Tom’s article: http://www.howwedrive.com/wp-content/uploads/2009/05/vanderbilt.pdf

  2. Perception vs. statistical reality is at the heart of most conversations I have with people about riding bikes, especially when it comes to sidewalk riding being much more dangerous than street riding. What I find discouraging is that most of these discussions/debates are held with people who rarely if ever ride a bike at all! They drive. In an attempt to get through to them, I always ask these drivers to recall the last scary interaction they had with a person on a bike; then ask if the bike was using the sidewalk or the street. So far: 100% sidewalk (or against traffic).

  3. Excellent observation Rantwick. I’ll have to ask that of my students in my Alternative Transportation classes.

  4. Great post!

    I want to do ChipSeal’s idea (from the comments of another post):

    Let’s pick a road, like University, and do 3 perspective videos—one dash-cam from a car in traffic, one watching traffic zoom past from the sidewalk and then one from the cyclist’s perspective. We could even use clips from Brian’s & my videos of University (I wore a forward-facing camera on that trek).

    While nothing substitutes for actually experiencing it, comparing the dramatic shift in perspective might encourage someone to try.

  5. Keri- I release you from any obligation to continue to reference that as my idea. I’m glad I brought it up, I am even more happy that you will act on it, but this idea properly belongs in the public domain. :)

    I wish to piggy back on Rantwick’s comment. We all often hear from “bicycle advocates” that lack of facilities is often cited as why folks won’t take up cycling. Well I call horse-feathers!

    Surveys may record people saying that, but I think it is just one more excuse from someone who will never ride a bike under any condition, because modern Americans avoid exercise! I doubt there are very many proto-cyclists waiting at the curb for conditions to change so they can go bicycle riding.

    It is hard for me to imagine more cyclists beyond double our present numbers- less than 5% of our population surely.

    There is a long list of myths that are closely held as a sheild against putting forth effort, and these are but two: “It is too dangerous”, “there are no safe places to ride without bike lanes”.

  6. ChipSeal wrote:
    “It is hard for me to imagine more cyclists beyond double our present numbers- less than 5% of our population surely.”

    Kevin’s comment:
    It is rather easy for me to imagine this. All I do is look out the window. Cycling and walking has a 34% commuter mode share here in the Riding of Toronto Centre.

    Peak oil is in the near-term future, but if there is a revolution in Saudi Arabia, car culture in the USA ends overnight. This is one of the few issues on which I find myself in agreement with one of the world’s most famous Saudi Arabians, Osama bin Laden.

    Of course, rather than waiting for a crisis, there could be reform in a non-crisis planned way. John Pucher describes some ways in which the USA can become more like Canada in his article, “Cycling in Canada and the United States: Why Canadians are so far ahead,” Plan Canada, March 2007, pp. 13-17 (with Ralph Buehler).

    Source for commuter mode share (and a truly fascinating map):

    http://www3.thestar.com/static/googlemaps/starmaps.html?xml=080830_commuters_walkandbike.xml

  7. Saudi Arabia supplies about 15% of our oil. I can’t imagine any Saudi government just switching off the tap; it’s what makes them viable as an influential nation. Since oil is sold on the global market, the price won’t change much.

    But the peak oil angle is indeed the big whammy. If the economy jumps up after this recession/depression the price of gas will skyrocket with it.