At 03:50 PM 9/19/2006, Robbie Webber wrote:
The one variable that has been most discussed on other lists is, "Where
was the author riding in relation to the entire lane?"
Here's the post to which Robbie refers, which was made to the national list
serve for folks who have been trained to teach vehicular cycling:
From the LCI list (sent by Dan Gutierrez -Sr. Project Engineer,
Milsatcom Systems Effectiveness, The Aerospace Corporation)
"In the article cited, the author of the study, of the effect of helmet
use on the behavior of motorist passing, was hit twice by motorists
during the conduct of the study. This makes me wonder if he was using
lateral lane positions that invited too close passing, hook turns and
other risky overtaking/crossing movements. If this is the case, then all
the study is measuring is the effect of helmet use in improper lane
positions. In my not so humble opinion as a LCI, anyone that was hit
twice during the conduct of a study has suspect traffic skills until
evidence to the contrary is presented. This "study" now makes me wonder
how close motorists pass cyclists with and without helmets when they ride
against traffic, or when they ride at night without lights (sarcasm intended).
.
In other words, it is likely that the author's behavior is a larger
contributor to close passing and his collisions than any apparently
systematic variation in driver reaction to helmet use. It would be nice
to see video of the author in action, because without this piece of data,
his conclusions are not guaranteed to carry over to the lower risk lane
positions. I bring this up because I know a number of cyclists that
swear up and down that motorists pass too closely in general, when under
observation we find that the cyclists in question use lane positions that
all but beg motorists to pass too closely in non-shareable travel lanes.
Even when they move a little further leftward, they are passed even more
closely, usually because they don't move far enough leftward to control
the lane and force lane changes.
Anyone riding this way would conclude by an improper extrapolation that
even further left would lead to collisions, not recognizing that beyond a
threshold, passing margin dramatically improves.
.
Of course I've got plenty of video data, even nice side by side
comparisons of video shot on the same road, same cyclist, same speed,
same traffic, separated by just a few minutes in time that show that
cyclist lane position is the overwhelming discriminator in motorist
passing behavior. In fact it shows that as a cyclist's lateral position
moves leftward, passing margin on average often goes down until the
transition to lane control occurs, then it suddenly jumps to much larger
lateral margin, and typically lower speed differential. This is result
is quite counterintuitive to cyclists that have never controlled a lane,
so the upshot is that most cyclists haven't mastered lane control well
enough to properly conduct this type of a study, or the similar one on
helmet use described above."
(and yes, it appears that, in addition to being a vehicular cyclist, Dan is
a rocket scientist)
chuck
Chuck Strawser
Madison Project Coordinator
Bicycle Federation of Wisconsin
106 E. Doty Street, Suite 400
Madison, WI 53703
voice: 608-251-4456
fax: 608-251-4594
www.bfw.org
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