Highway Contractor: Look Ma, No Strings!
HighwayContractor
by Dan Brown, Contributing Editor
To expedite production, Koss ran two belt placers ahead of
the paver (right). The first placer is partially visible (left).
Make it Last and
Make it Smooth
F
A Kansas project
delivers.
T he paver pushed only a small
head of concrete, which made
it easier to achieve excellent
smoothness numbers
or more than 30 miles, Interstate 70 in
western Kansas was worn out. It was
a full-depth asphalt pavement; sections ranged up to 20 inches deep. The most
recent asphalt treatments had lasted just five
to seven years, says Andrew Gisi, geotechnical engineer with the Kansas Department of
Transportation (KDOT).
The state wanted something that would
last longer, so KDOT chose a 6-inch bonded
concrete overlay – 1.45 million square
yards of it throughout nearly 31 miles.
Last year, Koss Construction milled out 6
inches and slipformed two projects with
concrete on 15.1 miles of four-lane interstate. Including shoulders, the two projects
totaled 725,000 square yards and cost $20.1
million. This year, Koss will mill and pave
two more similar projects on I-70 for a total
of 727,000 square yards at a cost of $21.9
million.
Koss’ smoothness numbers last year were
remarkable. Using a Guntert & Zimmerman
S850 four-track paver to pave 30 feet wide,
the contractor averaged just 8.5 inches of
deviation per mile from a zero blanking
band over the two projects. What’s more, the
Missouri-Kansas Chapter of the American
Concrete Pavement Association (ACPA) gave
Koss the “Smoothest Day Paving Award” for
a 4,500-foot section on which the contractor hit just 5.4 inches of deviation.
On every section of concrete pavement
last year, Koss earned a smoothness incentive from the state. To earn the maximum
smoothness incentive, Koss had to achieve 6
inches or less of deviation per mile.
The Colorado Department of
Transportation (CDOT) is an especially
important player in the Kansas situation,
because KDOT used Colorado’s pavement
design criteria and system in designing
Better Roads May 2012 5