Re: BCGP and Bike Lanes

[Peter Rosenfeld]

> 
> On Tuesday, July 23, 2002, at 09:33 AM, Peter Rosenfeld wrote:
> 
> > Where I draw the lines are facilities that increase or reinforce
> > excessively dangerous activities. Due to the high potential of
> > dooring in city areas, I feel that door zone bike lanes fit into
> > this category. In such a case, I would call the facility an "attractive
> > nuisance" in the legal sense. I also feel there are ethical issues
> > in knowingly designing a facility that gives a false sense of security.
> 
>       Let's put it into numbers. How many dooring deaths, linked to use of 
> bike lanes, do you consider excessive? I think the benefits of bike lanes 
> would be worth 10 deaths per state per year. So 500 deaths per year; less 
> than one in a million. Can you make the case that there are anywhere near 
> that many dooring deaths linked to bike lanes?
> 
>       Robert
> 


Why would you think bike lanes are worth 500 excess deaths a year?
Do you really mean this? Are you ready to go public with this statement? Do you 
have an official capacity with BCGP or any other planning organization?

Dooring deaths are hard to estimate due to the rarity of all bike deaths. The 
example you gave of 500 excess deaths a year would be increasing the number of 
deaths from around 800 to 1300, a 63% increase. If you think the political aims 
of lanes are worth such a large number of deaths, I have nothing to say to you 
and recommend that all planning organizations disassociate themselves from you. 

Serious accidents are much more common. Recent studies indicate that in urban 
areas with parallel parking, dooring injuries account for a significant fraction 
of all car/bike collisions. In Santa Barbara such bike lanes seem to be 
associated with an increase of doorings from 7.4% of all car/bike collisions to 
16%. Other studies have indicated that dooring deaths are just as serious as 
other car/bike collisions. So we are talking about a very significant number of 
serious injuries. 

However, because nationally most bicyclists are not exposed to situations that 
can result in dooring, they are not a common accident, accounting for about 0.8% 
of all car/bike accidents.

So for death numbers: Nationally, assuming doorings cause deaths in proportion 
to their injury rate ( which seems reasonable given the injury severity) you 
would expect dooring to result in less than 1 percent of deaths, on the order of 
8 deaths. Very low down in the noise.  In places like Santa Barbara, Boston, and 
Philadelphia, maybe 7 to 16% of deaths. Since a place like Philadelphia has, 
what, maybe 6 or 7  bike deaths a year, this would translate into one extra 
death every 1 to 2 years if I worked the numbers correctly.

-Peter Rosenfeld

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