dan baker said:[email hidden] (dan baker) wrote in message
Quoted message said:anybody have any other examples, specs, or feedback on a
"dirt-colored" shoulder that could be installed adjacent
to a "regular" asphalt traffic lane without affecting
drainage or creating an unbikable grade separation?
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nothing? nobody has encountered colored asphalt shoulders
anywhere?
d
dot.state.fl.usped bike reportsOpen ↗
.htm#Red%20Shoulders
is a study evaluating red shoulders. I haven't examined it
closely, but I would be very dubious of any findings and
conclusions. The study was performed by UNC Highway Safety
Research Center, my former place of employment, and their
track record on bicycling research is terrible. I've
critiqued several noteworthy papers of theirs, including a
couple I worked on, and shown that they are methodologically
weak/garbage and the conclusions unsupported.
Here's what ITE thinks about lane narrowing. And though it
is not quite the same as shoulder coloring, it is in the
same category of psychoperceptual control.
Traffic Calming: State of the Practice ITE/FHWA, August 1999
ite.orgtcstate.htmOpen ↗
ISBN 0-935403-36-1 © 1999 Institute of Transportation
Engineers. All rights reserved. Publication No. IR-098
ite.orgChapter5c.pdfOpen ↗
“Painting an edgeline several feet from the pavement edge
has the effect of visually narrowing the roadway. A
double yellow line striped down the center of roadway
might have a comparable effect, visually limiting drivers
to half of the road.
In theory, the perceived narrowing could cause a modest
speed reduction, just as a real narrowing causes a modest
speed reduction. The theory is not borne out by empirical
studies. Results from Howard County, MD, Beaverton, OR,
and San Antonio, TX, suggest that vehicle operating
speeds are as likely to increase as decrease with
striping. One explanation is that centerlines and
edgelines define the vehicle travel path more clearly,
creating a gun barrel effect.
Results from the aforementioned studies could be dismissed
because even with the narrowings, pavement and lane widths
remained substantial. Yet, results from Orlando, FL, where
travel lanes were taken down to 9 feet, showed speeds to be
unaffected (see figure 5.47).27 This psychoperception
control was not “tricking” anyone and hence was removed from
both the centerline and edgelines."
I live in NC and haven't seen colored shoulders. That is not
to say they don't exist here though. Its a big state and I
haven't biked everywhere.
I personally would strongly argue against them though. NMDOT
is trying to save money at bicyclists' expense. Any shoulder
where bicycle travel is expected/encouraged should be the
same pavement quality as the standard lane. I can't imagine
that a sand sealed surface wouldn't be worse, and eventually
result in sand coming loose and being slippery. And why
would they think that bicyclists need extra traction beyond
a normal ashpalt? Sounds like they are rationalizing cheap
pavement to me.
Wayne www.humantransport.org
