|
An Inexpensive Maintenance Plan
That Works!
Surveys of motorists consistently
show that pavement condition is
their number one priority. And
while county and municipal road
officials aren’t often the subject of polls,
it’s clear that maintaining pavements in
the smoothest possible fashion for the
least dollars tops the “to do” lists of most.
It’s nice to have the luxury of totally
removing old pavement and starting over,
or milling top layers and putting on two
inches or more of new asphalt. But that
doesn’t often happen on the thousands of
miles of rural asphalt roads in our state,
and the thousands of miles of asphalt
streets in cities, where road life extension
is job one.
A relatively new solution is thin hot mix
asphalt overlays, which can meet the needs
of motorists and public officials. Research
at state and national levels show thin
overlays are a clearly successful and
cost-effective alternative to more
traditional “chip and seal” or slurry
and microsurfacing techniques, and far
more useful than experimental programs
such as so-called “whitetopping”
with concrete.
Thin overlays of 1/2 to 1 1/2 inch provide
real structural strength to a road, improves
ride quality by correcting surface defects,
and adds to the quietness of roads,
addressing the increasingly volatile issue
of noise pollution. It gives drivers the
impression that they are enjoying a brand
new road, at only a fraction of the cost.
The timing and quality of the maintenance
and rehabilitation of road surfaces
is critical. If pavements can be resurfaced
while still in fair condition, the repairs
generally cost about one-fourth the cost
of repairing roads in poor condition, reducing
the overall life cycle costs of the road.
Thin overlays, when used properly, can
enhance the safety of roads. Safety is
largely a function of maintaining tire
contact with the pavement surface, and
smoothness helps that. Safety is also
related to skid resistance, and an overlay
increases skid resistance. It also re-establishes
a crown, reduces road spray, and
allows new pavement markings.
Duane Ellis, Public Works Director for
the City of Mount Pleasant, says that his
experience with thin overlays during the
last two years has been “good,” and he
calls the overlays an important tool in
their “street fixes toolbox.” Indeed, the
city is already planning overlays on city
streets next year, with a contract just let,
as well as on the taxiways and aprons of
the Mount Pleasant Municipal airport.
But, he noted, its important that the overlays
not be placed in areas with “working”
cracks, such as fatigue cracking or severe
reflective cracks that continue to move.
Alternatives to thin overlays fall short.
Chip seals do not add structural strength,
and lead to citizen complaints about tar
spray and broken windshields. Slurry and
microsurfacing means high cost with no
additional structural strength, and no real
change in road surface defects.
Whitetopping is time consuming, putting
drivers off roads during lengthy curing
periods. Concrete can’t be as smooth as
asphalt, and tining creates noise problems.
Because whitetopping is still experimental,
evaluations of effectiveness are mixed.
And once a whitetopped road experiences
failure, it needs to be removed and
rebuilt completely.
With 94 percent of roads around the
nation surfaced with asphalt, thin
overlays make sense as repair and
maintenance mechanism.
For more information about thin asphalt overlays,
please contact the Michigan Asphalt Paving Association
at (800) 292-5959. |
