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One of Michigan’s oldest roads
is now one of its newest
By Dave Morningstar
When the Michigan Department
of Transportation (MDOT)
decided to take bids on the
contract to replace a 2-mile section
of Telegraph Road near Pontiac, the
Department knew the high-visibility
project would present a major challenge
for everyone involved. The portion of
Telegraph Road linking Detroit and
Pontiac is one of the oldest roads
in Michigan, and the section being
replaced was part of a major upgrade
completed in the late 1950s.
“Of course, road building technology
was different then,” explains Dennis
Cooper, MDOT Project Engineer.
“Then it was common to build roads
on pretty much whatever was there,
including clay, which doesn’t drain
well, if at all. All in all, this section
of road had aged well past its normal
useful life, and it was time to replace it
from the base up.”
Dan’s Excavating, Inc., took on the task
when it won the bid for the seven-lane
road, one of the busiest non-freeway
routes in Oakland County, Michigan.
MDOT’s specifications for the project
included a new Superpave asphalt
roadway, and Dan’s Excavating turned
to Ajax Paving Industries, Inc., to supply
the paving technology for that part of
the project.
“The project involves removing the
entire existing roadway and replacing
it with a new sand sub-base, a new
21AA gravel base, and three lifts of
new asphalt pavement,” Cooper
says. “Of course, it will be built
to the most current specifications,
including features like edge drains
that weren’t even available in the
late 1950s.”
Incentives and a Little Luck
It also is a “lane-rental” project and
falls under the new Percent Within
Limits (PWL) quality assurance
protocol being used by MDOT.
“Lane rental is something we’ve
worked with many times before,”
says Brad Hillard, Project Manager at
Ajax. “We recently completed a major
rebuild on a section of I-75 in Oakland
County under a lane-rental contract, so
we understand the process very well.”
Under a lane-rental arrangement, the
contractor pays a fee to MDOT for
every hour a lane is unavailable for
use by the public. The estimated lane-rental
costs are included in the bid. This
arrangement provides an incentive to
finish the project as quickly as possible
and with an absolute minimum of disruption
to the public.
“We committed extra resources to complete
the road ahead of schedule because
we knew it was a major benefit to our
customers, Dan’s, MDOT, and the public
on this project,” Hillard says.
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Percent Within Limits (PWL) is considered
by the federal government as the best quality
assurance test for asphalt available. As a
result, many state highway agencies use the
system, which was originally developed in
the 1970s to replace an older method first
devised by the military.
PWL is based on a percentage of the lot falling
above the lower specification limit (LSL),
below the upper specification limit (USL), or
between the two. The PWL for a given pavement
characteristic, including but not limited
to layer thickness, in-place density, and
asphalt content, is determined case by case.
Once ranges are determined, samples are
evaluated to estimate the percentage of the
lot falling within the specified limits. Because
of the mean and standard deviation of test
results, a percentage of the material can
test outside the acceptable range. When this
happens, a reevaluation of the test results is
conducted before penalties ensue.
The use of penalties normally begins when
the PWL falls below a certain level. If test
results are unacceptably low, the contractor
is required to remove and replace the lot of
material, and pay factors may decrease. On
the other hand, if the contractor exceeds
the PWL range, an agency may award the
contractor a bonus. |
According to Hillard, there was a lot of
overtime work involved. “It was 24/7
whenever we could arrange it,” he says.
“And with the amount of preplanning
and coordination we did with Dan’s and
the other subcontractors, we cut quite a
bit of the time out of the schedule.”
Due to a mild spring in Michigan, Ajax
was able to open the asphalt plant dedicated
to this project in April, almost two
weeks earlier than normal. As a result
of the favorable weather, a significant
amount of the paving was completed
in the second half of April and the first
weeks of May.
High-Performance Materials
“Ajax placed 55,000 tons of asphalt
on this project,” notes Tom Ziegler,
Consulting Technician in charge of
asphalt operations for Parsons Brinkerhoff,
which engineered the project. The
pavement consisted of a 4-inch base lift
of 3E10, a 3-inch leveling lift of 3E10
High Stress, and a top lift of 5E10
High Stress.
“These are all high-performance materials,”
Ziegler says. “The first digit designates
a gradation band and volumetric
requirements. The ‘E’ is an indication
of the Equivalent Single Axle Load
(ESAL) rating of the mix, a measure of
its durability. In this case, an E10 means
the pavement has a projected life of 10
million ESALs, which is very good.”
Placing such high-performance materials
presents its own set of challenges.
Because there are strict limits on how
much time the mix can spend on a truck
before it’s installed, Ajax had to use an
asphalt transfer machine on this project.
The transfer machine runs between the
asphalt delivery trucks and the asphalt
paver. The transfer machine allows the
trucks to dump their loads and have
another truck back into the transfer
machine to dump its load, without having
to stop the paving machine or the
paving operations.
“The transfer machine let us run a
continuous paving operation, which is
necessary to meet the quality standards
for a project of this kind,” Hillard
notes. “Making this kind of operation
work required a lot of planning and
preparation from the field crew to keep
everything running smoothly. The added
productivity we gained by using the
transfer machine really helped us stay
on schedule because this was a Percent
Within Limits (PWL) project, and
that can slow things down. It’s a good
method for quality control, but it does
require very careful scheduling if you
are going to avoid downtime.”
Tough Testing Protocol
The PWL process requires the contractor
to lay and compact a 750-ton test
strip from each type of asphalt prior to
proceeding with the installation. The
test strip is analyzed for density and other parameters, and if it passes, the
batch goes into production.
“Superpave mixes, like the 3E10 and
5E10 we used here, require very specific
installation procedures,” Hillard says.
“You have to take more care in the
rolling patterns to make sure you are
achieving the specified density. On this
project, for example, we used three
rollers in series and had someone behind
each one checking density as they
compacted the mix. It requires a really
skilled operator to keep the roller at the
right speed, the right distance apart, and
the right distance behind the paver to
achieve the desired result. It’s even more
complicated because all those parameters
change as the temperature of the
asphalt changes.”
Quality and Craftsmanship
Ziegler of Parsons Brinkerhoff was
impressed with the workflow. On June
21, MDOT announced that contracting
crews had opened both directions
of Telegraph Road, 23 days ahead of
schedule. “Everyone on this project
did an outstanding job,” he says. “To
maintain access to the businesses along
Telegraph, Ajax had to work the two
sides of the road separately and then
join them in the middle. Normally, you
would expect to need a little ‘fudge factor’
to get the two halves to meet, and
that’s pretty typical.”
But not on this project. “They had to
use a paver extension to reach over the
crown and match the two slopes, and
the project came out as a perfect match
in the middle,” Ziegler says. “That
speaks volumes about the quality and
craftsmanship of Ajax.”
Cooper echoes Ziegler’s observation.
“The team assembled for this project
did an outstanding job,” he says.
“Everyone came together and provided
a great product to the public. It’s one of
the best projects I’ve been on.”
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