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 Shoulders

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