any info on bikable "sand-seal" shoulder surface (NC)

[Dan Baker]

There are a couple re-surfacing projects contemplated in
New Mexico right now where the design engineers are
considering some type of "sand-seal" surface treatment for
the shoulder. The idea is that having a "dirt-colored"
shoulder provides visual separation from the traffic lane,
might slow traffic a little since it would make the road
look narrower, and if done "properly" would provide a
smooth high-friction bikable surface.

The problem is that none of the NMDOT engineers have ever
specified or used a sand-seal treatment, and dont know
exactly what to do to create a good surface for bikes. All
they know how to do is horrible "chunk-and-seal."

I found some specs on the NCDOT website, which leads me to
believe that they may do this type of surfacing.... My
question to ya'll is whether it is a good ridable surface?
feedback on this?

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?

thanks,

Dan

 

[Dan Baker]

[email protected] (dan baker) wrote in message
> 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?
> --------------

nothing? nobody has encountered colored asphalt
shoulders anywhere?

d

 

[Rick Onanian]

On 25 Jun 2004 14:36:24 -0700, [email protected] (dan baker) wrote:
>nothing? nobody has encountered colored asphalt shoulders
>anywhere?

In certain areas of Massachusetts, I've seen _huge_ green
shoulders on a freeway. I believe it was route 2 or 190,
north/west of Worcester, or route 290. The road is two lanes
wide, with probably two to six lanes worth of green pavement
on one or both sides.

In considering why they exist, I figure it may be for future
expansion and/or snow removal (gotta put it somewhere!).
They appear to be painted green, not dyed, and some areas
have faded a bit, but they get the point across that it's
not an area to drive on.
--
Rick Onanian

 

[Wayne Pein]

dan baker wrote:
> [email protected] (dan baker) wrote in message
>
>>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?
>>--------------
>
>
> nothing? nobody has encountered colored asphalt shoulders
> anywhere?
>
> d

http://www.dot.state.fl.us/Safety/ped_bike/ped_bike_reports-
.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
http://www.ite.org/traffic/tcstate.htm#tcsop

ISBN 0-935403-36-1 © 1999 Institute of Transportation
Engineers. All rights reserved. Publication No. IR-098

http://www.ite.org/traffic/tcsop/Chapter5c.pdf

“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

 

[Dan Baker]

Wayne Pein <[email protected]> wrote in message news:<[email protected]>...
> dan baker wrote:
> > [email protected] (dan baker) wrote in message
> >
> >>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?
> >>......
> 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
-----------------------------------------

actually, they are not trying to take the cheapest way out
(this time). they are even willing to spend slightly MORE
that "regular" OFC asphalt for the shoulders, if they can
specify a solution that meets criteria.

To the credit of NMDOT, they have been working with me to
make sure the surface IS bikable (smooth, not loose, and high-
friction) before they install it ***** nilly. They are
attempting to balance the desire and demand from us bikers
to have a shoulder, with the hue and cry from semi-rural
residents and historical committees who voice the desire to
stick with 20' wide roads with NO shoulders to minimize
"visual impact" and cost.

Some tech specs I have been able to dig up indicate that
there are specific types of "sand seal" that involve closely
controlled application of an even layer of emulsified
asphalt, followed by even application of a fine (#2, #4)
blotting sand, followed by rolling and sweeping. I just
haven't been able to find anybody who actually does it, or
can vouch for the results.

If I can find some physical examples, and a couple
testimonials for or against, I would like to be able to hand
this info to the NMDOT to assist in a decision as soon as
possible so we can get a couple big construction projects
finished up.

d