(dramatic music) (logo whooshing)
- [Narrator] Weather conditions
around Texas make roadway maintenance
a locally unique endeavor.
In North Texas, for example, snowplows are necessary
for clearing the roads during winter.
That often results in ripping up
retroreflective pavement markers, or RPMs,
which are raised safety devices on the roadway
that helps drivers navigate hazards.
Building on a previous research project,
the Texas Department of Transportation determine how
to protect RPMs within the current infrastructure.
- My whole point of this is that every winter we plow off
millions of dollars worth of RPMs
while we're plowing snow off of our highways.
The RPMs come off with the snow
through this process, and so we have
to replace 'em every year.
So the thought is if we put these RPMs
and recess 'em in these already
existing milled rumble strips, that
that when we come back
through the plow, we won't plow 'em off.
- And one of the major things is that we wanted to make sure
that people can actually see
the retroflective pavement markers while
installed in the rumble strips.
For the previous project, we did it with a small team.
For this project, we actually did human nighttime visibility
studies in which we recruited participants to
participate in the project to determine
whether they can actually see it.
- [Glenn] This particular project, it really went in
and looked at that reflectivity values to make sure
that it was still meeting our standards, even though
that they were recessed into the pavement.
- [Raissa] Our results essentially showed
that the markers had a really high survival rates when they
were installed in that approach compared
to surface mounting markers.
In addition, based off of some work that we did on
that project, we found that the visibility
was approximately around 900 feet.
- During the winter,
we would plow these reflective pavement markers off the road
and while we would come back
and install 'em at a later date, there was a number
of months where those markers were
non-existent on our highways.
And so by putting 'em in these milled rumble strips
and recessing 'em where they're not plowed off,
they're on the highway all the time.
- And when we think about how much money is going
to be saved, we estimated around $3.5 million a year
just based off of having these RPMs in the pavement.
And I would say that's a conservative estimate
because we estimated around 75% of them are going
to persist, and it's likely that that could be higher.
One of the key findings is that the rumble strips need
to be at a certain depth.
So we're looking at developing approach,
perhaps using lasers in which we can quickly scan
existing rumble strips to determine whether they're at the
appropriate depths, so that way this method can be deployed.
In terms of future highways in which you are now cutting in
new rumble strips, the major next steps will be to make sure
that contractors can cut these rumble strips
at the appropriate depths and tolerances.
So we are creating recommendations for contractors.
- [Narrator] For more information
and to find the publication for this project,
please visit the Tex DOT research library
at the link shown below.