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“Putting in a brand-new casting and
new concrete riser rings is certainly
a durable and high-quality fix,” said
Myers, “but excavating, and then setting
and adjusting the new casting and
rings could easily take all day.
Myers’ views on the high labor costs
associated with traditional manhole
raising are backed up by data from
municipalities across the nation. A
study in Shoreline, Wash., analyzed
three years of maintenance records and
determined that raising manholes carried
an average cost of $500 per manhole
for labor and materials. In this
case, the district was covering the manhole
at time of paving, then jackhammering
new pavement at a later date
before digging out the manhole frame
and raising with precast grade rings. In
a similar scenario, the southern California
city of Ontario found that labor
costs were $360 per manhole when
using precast grade rings. Considering
that many municipalities must budget
for dozens, or even hundreds, of manholes,
the costs can quickly become
substantial.
“Pressed In Bearing Fit” insures riser will
never move in casting.
Even worse, this traditional process
may cause more harm than good. Hot
patching, or the use of hot mix asphalt,
to fill in excavated pavement has
a proven negative affect on quality and
roadway durability. This is mainly due
to the inevitably uneven joint between
smooth, newly installed pavement
and the rough, lower-quality hot mix
patch.
In his 2004 report, “A Look at the
Effects of Manholes on Street Condition,”
Steve Rinne surveyed 480
manholes in Kansas City. Of those, 30
percent were found to be substantially
above or below grade. The pavement
Riser Heights starting at ¾” and going up in ¼” increments.
around the observed manholes was
also assessed. Around the uneven manholes,
35 percent of the pavement was
rated as “bad,” as opposed to just 11
percent of the pavement surrounding
at-grade manholes. These numbers
certainly suggest that uneven manholes
contribute to pavement wear.
To put it another way, “smooth pavement
lasts longer,” according to the
National Asphalt Paving Association’s
report, “Thin Asphalt Overlay for
Pavement Preservation.”
Better for New Philadelphia
In contrast to the standard manhole
raising technique, AHP adjustable
risers can take as little as ten minutes
to install. Even better, there’s no excavation
or hot patching required.
The secret is the pivoted turnbuckle;
American Highway Products manhole
risers are open, flexible rings made of
high-quality, galvanized steel that can
be expanded or contracted easily with
a screwdriver. They’re available in precisely
sized diameter and thickness increments,
which allows crews to bring
manholes to exact new paving surface
grades.
“We order them as needed, in the sizes
we need, and they always get to us
in a timely manner,” says Myers. “It’s a
great product, and they’re a great company
to work with—we’ve never had
any complaints.”
The whole installation process is simple:
just place the new riser where you
need it and crank the turnbuckle until
it’s seated securely and tightly. Instead
of one or two days to raise a single
manhole to grade, the AHP adjustable
risers make it feasible to raise dozens
of manholes in a day, all while avoiding
extensive traffic closures. In 2019,
New Philadelphia installed 35 of the
pivoted turnbuckle risers, including 25
on a single resurfacing project.
In addition to quality benefits and labor
savings, installing adjustable manhole
risers offer an additional advantage
over the more-traditional manhole
raising method: safety. When manholes
are raised to new grade quickly
during paving operations, exposure to
traffic and construction equipment is
minimal. That’s not to mention the
sizable weight of the manhole raising
equipment that’s often used; heavy,
precast grade rings can cause lifting,
crushing, or pinching injuries, and
they can happen during delivery, storage,
loading and construction. These
risks simply do not exist when using
AHP’s galvanized steel rings, which
are considerably lighter yet still sturdy
enough for the job.
Altogether, AHP’s manhole risers
have provided an easy solution for a
common problem and, in turn, have
helped make Myers job just a bit easier.
“I like them and think they’re a better
solution,” said Myers, “so now its
adjustable risers that are our standard
practice.”
Angus Stocking is a former licensed land
surveyor who has been writing about
infrastructure since 2002. American
Highway Products can be reached at
1-888-272-2397 or by email at
[email protected]
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www.callape.com 1.800.210.5923