Behalf Of John Forester
Sent: Thursday, November 01, 2012 5:43 PM
To: Chainguard
Subject: [CG] Route Infrastructure and the Risk of Injury to Bicyclists,
Review

There has been considerable commentary about the paper by Treschke et al
titled Route Infrastructure and the Risk of Injury to Bicyclists, American
Journal of Public Health, current issue or thereabouts. The paper looks
stupendously important, with its long list of public health professionals
authoring it and using very complicated mathematical programs, and the use
of data about two points in each trip: where the cyclist crashed, and
another point where he didn't crash. Much is made of the claim that cycle
tracks are far and away the safest kind of bicycling facility. However, what
we actually have before us is the result when total ignorance of traffic
engineering combines with bicycle advocacy ideology. I have written a review
of this paper and posted it on my website. For convenience to current email
readers, I post only the Conclusions section here.

Conclusions
I find that this paper (Treschke et al, Route Infrastructure and the Risk of
Injury to Bicyclists) does not deserve serious consideration for two kinds
of defects: the combination of incompetent traffic-engineering with
ideological argument. I offer two examples of this combination.
When considering the small reduction in crash rate produced by bike lanes
versus the larger reduction produced by the absence of parked cars, the
authors chose to advocate that produced by the bike lanes that they favor.
When considering the astonishing reduction in crash rate produced by cycle
tracks, as shown by their data, the authors chose to proclaim that reduction
as genuine for cycle tracks in general.
In the bike-lane issue, the authors chose to proclaim the effect of bike
lanes, small though it was, rather than the larger effect of the absence of
parking. That combines traffic-engineering incompetence with ideological
propaganda.
In the much more impressive cycle-track issue, the authors proclaimed
enormous crash reduction without informing the readers of the two relevant
facts. First, that their data came from only one installation.
Second, that that installation was not along a typical city street but in
the only situation in which a plain cycle track could possibly be safe, a
place without crossing or turning movements by motorists, cyclists, or
pedestrians. The authors refer to the forty-year-old cycle-track controversy
as if they had studied it, but clearly they don't understand it. It is clear
that the authors have such faith in the cycle-track concept that its
astonishing data failed to alert them to investigate why such data was
reported.
The authors' failure to understand the difficulties of cycle tracks and the
only conditions in which cycle tracks may be safe constitute
traffic-engineering incompetence.
The authors' proclamation of the great safety of cycle tracks and their
failure to be alerted to problems with the source of their cycle-track data
demonstrate the improper influence of ideological considerations.

The URL for my full review of the Treschke paper is at:
http://johnforester.com/Articles/Facilities/Infrastructure%20&%20Inju...
f

--
John Forester, MS, PE
Bicycle Transportation Engineer
7585 Church St. Lemon Grove CA 91945-2306
619-644-5481    fores...@johnforester.com
www.johnforester.com

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