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From: Zen Cycle <funkmaster@hotmail.com>
Newsgroups: rec.bicycles.tech
Subject: Re: Some traffic stats
Date: Thu, 14 Mar 2024 08:42:21 -0400
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On 3/14/2024 1:53 AM, Jeff Liebermann wrote:
> On Thu, 14 Mar 2024 00:00:45 -0400, Frank Krygowski
> <frkrygow@sbcglobal.net> wrote:
> 
>> On 3/13/2024 4:06 PM, Zen Cycle wrote:
>>> On 3/13/2024 3:44 PM, Frank Krygowski wrote:
>>>> On 3/13/2024 11:34 AM, AMuzi wrote:
>>>>> https://www.cityofmadison.com/police/newsroom/incidentreports/incident.cfm?id=30855
>>>>
>>>>   From that site:
>>>>
>>>> * On average, every day, twenty pedestrians are killed by a moving
>>>> vehicle in the United States.
>>>>
>>>> * Approximately 76,000 pedestrians and 47,000 bicyclists are injured
>>>> in roadway crashes annually in the United States.
>>>>
>>>> I'll note that the figures for pedestrians are far worse than for
>>>> bicyclists. Yet the general public thinks of bicycling as much more
>>>> dangerous than walking.
>>>
>>> I think if you compare injuries per participants or injuries per miles
>>> traveled, you'll see they're probably correct.
>>
>> That's far from certain.
>>
>> Powell et. al., “Injury Rates from Walking, Gardening, Weightlifting,
>> Outdoor Bicycling and Aerobics”, Medicine & Science in Sports &
>> Exercise, 1998, Vol. 30 pp. 1246-9 polled over 5000 people who had
>> chosen at least one of those activities for exercise. One question was
>> whether the participant had incurred an injury during the previous month.
>>
>> The results:
>> Weightlifting: 2.4% of participants injured
>> Gardening or yard work: 1.6%
>> Aerobic Dance: 1.4%
>> Walking for exercise: 1.4%
>> Outdoor bicycling: 0.9%
> 
> Such surveys require a control group to be valid.  I suspect that if
> someone was able to do NOTHING for one month, they would still have
> been involved in some kind of accident.

Meh...I don't think it's all that relevant for pure statistical 
analysis. Do you really need a control group to compare injury rates per 
mile for walking vs cycling? I don't think so.

> 
>> And while injuries =/= fatalities, Dr. John Pucher of Rutgers has
>> published (in "Making Walking and Cycling Safer: Lessons from Europe")
>> an estimate from U.S. data that bicyclists suffer 109 fatalities per
>> billion km ridden.  Pedestrians suffer 362 fatalities per billion km,
>> three times as bad!
>>
>> Pucher's number works out to 5.7 million miles ridden per fatality for
>> cyclists, 1.7 million miles walked per fatality for pedestrians. And
>> Pucher's later work, as well as other sources, show he greatly
>> overstated the bicycling risk. It's now widely accepted that Americans
>> ride over ten million miles between fatalities.
> 
> Americans ride over 10 million miles between fatalities?  Most
> Americans don't ride after their first fatality.  The value of
> exercise after death has been greatly overrated.
> 
>> British data for decades has consistently found more pedestrian
>> fatalities per mile traveled than bicycling fatalities per mile. AFAIK,
>> there have been only a couple years in the past 20 where the reverse was
>> true. I've also seen Australian data showing the same result.
>>
>> In any case, for most Americans the far bigger danger is sitting on the
>> couch.
> 
> If someone asked you "what is your favorite sport and how many times
> have you been injured in the previous month", would you produce an
> accurate number, or would you minimize the number of injuries?  My
> past experience working with such surveys suggests that most people
> would not admit to an injury. 

True, self-reporting surveys are always suspect. One would suspect just 
the participation rates are highly suspect, as noted in the massive 
differences between the referenced NHIS study and the ICARIS study.


> I also find it odd that the survey
> would ask if "the participant had incurred an injury" instead of
> asking how many injuries.  Why only one month?  Were they worried that
> if they extended the time period to one year, a much larger percentage
> would probably have been injured at least once.  Also, was the month
> the same for everyone in the survey?  I suspect not or the question
> would have been phrased differently.  

That was all detailed in the body of the study. They discussed 
specifically why only 30 days, and FYI, it was the "past 30 days".


> For cycling, if they selected a
> month which has a high accident rate, typically when everyone is
> cycling, the survey results would have been very different had they
> selected a month with a low accident rate.  Time of day when riding
> would also have had a huge effect on the accident rate.  Were riders
> who died included in the survey?  Traditionally, the dead do not
> answer survey questions.

The dead aren't liekly to be interviewed at all. The ICARIS study 
referred to in Powell et al was based on USDOT data and included 
reported deaths.

>  How far did they ride in the month of the
> survey?  If it was rather long distances, the chances of having an
> accident would be much higher than if they rode short distances.

True, the Powell study didn't address that as part of the survey, which 
is one reason I noted to frank that it leaves me unconvinced.

> 
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