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The
Asphalt
Pavement Alliance designated nine road agencies as winners of its
Perpetual Pavement Awards for 2004. The awards will be formally presented by
Jack Lettiere, Jr., 2005 President of the American Association of State
Highway and Transportation Officials, at a special ceremony on May 18 at the
National Center for Asphalt Technology at Auburn University, Auburn,
Alabama.
To qualify for APA’s Perpetual Pavement award, a
pavement must meet strict criteria and it must have been constructed at
least 35 years ago. Engineers at NCAT evaluated the nominations and a panel
of industry experts validated the winners.
Here is a brief snapshot of each award-winning
road.
County of Santa Clara Roads and Airports Department
 The
County of Santa Clara’s award-winning pavement is the 5.7-mile, westernmost
stretch of Central Expressway, a section of the four-lane, divided highway
that passes through the cities of Mountain View and Sunnyvale. Opened with
an average daily traffic count of 12,000 vehicles in 1969, the road
currently handles an ADT of 50,000.
The original construction consisted of 8 inches of
aggregate subbase, 8 inches of cement-treated base, and 4 inches of hot-mix
asphalt. The county placed a 1.5-inch asphalt overlay on the highway in 1986
and sealed it with microsurfacing in 2003. The road is still in use and the
pavement is considered sound and viable.
Ohio Department of Transportation
 The
Ohio DOT’s award-winning pavement is the southbound section of SR 25 in Wood
County that runs approximately 5 miles from Perrysburg to a point 0.33 miles
north of SR 582. It was originally built between 1937 and 1940, and was one
of the first deep-strength asphalt pavements built in Ohio.
“This 5-mile-long section of pavement was
constructed 67 years ago with technology that’s still relevant today,” says
Todd M. Audet, P.E., ODOT’s District Two Deputy Director. The pavement
currently has an average daily traffic of 11,000 vehicles, 4% of which are
trucks.
Originally constructed as an 8.5-inch-thick
tar-bound macadam roadway, the existing pavement was overlaid with 2.25
inches of asphalt in 1948, with 1 inch of asphalt in 1965, and with 1.5
inches of asphalt in 1983 and 1990. In 2003, 3.25 inches of the pavement was
milled and replaced.
Minnesota Department of Transportation
 The
award-winning pavement is a 3-mile section of TH 10 between mileposts 224
and 227. The highway was opened to traffic in 1966 and has withstood
13.5-million ESALs in the intervening 42 years.
The original road was constructed with 18 inches of
select granular material for a subbase, 6 inches of aggregate base, 3 inches
of bituminous base, and 3 inches of bituminous binder course with a 1-inch
asphalt surface course.
The pavement was overlaid with a 0.5-inch wearing
course in 1978, then milled 2 inches and overlaid with 3.5 inches of
asphalt.
“This road has lasted because of good structural
design and good pavement design,” commented Patrick Hughes, Metro District
Engineer for the Minnesota Department of Transportation. “The wearing course
that we used back in 1962 was 100% crushed material — probably close to the
Superpave materials of today.”
Kentucky Transportation Cabinet, Department of Highways
 Kentucky’s
award-winning perpetual pavement is a 27-mile stretch of the Julian
Carroll-Jackson Purchase Parkway in Graves and Marshall Counties, extending
from milepost 25.384 to milepost 52.333. Opened to traffic in 1968, the
southern portion of the road has handled an estimated 14-million ESALs and
the northern portion more than 22-million ESALs.
The parkway was originally constructed with a
13-inch cement-treated bank-gravel base topped by 6.5 inches of hot-mix
asphalt. In its 36 years of service, the pavement has required only one
overlay of 1 to 1.5 inches of asphalt.
Samuel H. Beverage, State Highway Engineer, lauded
the pavement’s performance and that its minimal repair costs represent “a
significant saving to the traveling public.”
Colorado Department of Transportation
 The
Colorado DOT’s award-winning pavement is a 4.8-mile stretch of U.S. Highway
85 between Denver and Greeley. It carries heavy commuter traffic as well as
considerable truck traffic from produce farms and gravel pits in the area.
Opened to traffic in 1957, the road was constructed
with a 4-inch aggregate base and 3 inches of hot-mix asphalt. Over the next
47 years, the pavement received three overlays. Part of the original
pavement was overlaid with 1.5 inches of asphalt in 1971 and the rest with
1.25 inches of asphalt in 1972. The entire section got a 1.5-inch overlay in
1986, followed by a 4-inch asphalt overlay last year.
Although the original pavement was designed for 2-
million Equivalent Single Axle Loads, to date it has withstood an estimated
load of 7.9-million ESALs. The average daily traffic on the road is 19,000
vehicles.
“There are several reasons why this road has lasted
so long,” said Jay Goldbaum, Pavement Design Engineer with the Colorado
Department of Transportation. “One is the department’s attention to
maintaining their roads in good condition. We have a proactive response to
deteriorating pavements. We’ve monitored the condition of the road, and
applied timely treatments. We also selected the correct rehabilitation
programs for the road.”
Illinois Department of Transportation
 The
Illinois DOT’s award-winning pavement is a 2-mile section of I-180 between
mileposts 9.5 and 11.4. The highway was built to connect a new steel mill to
I-80 and was opened to traffic in 1969.
This 2-mile section of the highway was constructed
over a marsh with very unstable soils. The Illinois DOT chose to use
full-depth asphalt in this area to accommodate the concerns about
settlement. It was the first full-depth asphalt pavement built on the
Interstate system in Illinois, and has withstood approximately 5.1-million
Equivalent Single Axle Loads since it was opened to traffic.
The section was built with a granular subbase, a
12-inch asphalt stabilized base course, a 2.5-inch binder course, and a
1.5-inch surface course. The pavement was milled and overlaid with 1 inch of
asphalt in 1987 and another 2 inches in 2001. The section has outperformed
other sections of the road and has not required any full-depth patches to
date.
“The uniform soil conditions that the thick hot-mix
asphalt pavement was placed on helped ensure the long life of this
pavement,” said Eric Harm, deputy director, assistant chief engineer. He
also praised the uniformity of the asphalt mixes and the lay-down procedures
that produced the pavement.
South Carolina Department of Transportation
 South
Carolina’s award-winning pavement is a 5-mile section of Interstate 26 in
Spartanburg County between the North Carolina state line and South Carolina
Route 11. The highway opened to traf-fic in 1969.
The original construction of the road consisted of
3.8 inches of aggregate subbase, 7 inches of aggregate base course, 6.3
inches of asphalt aggregate base, 2.4 inches of asphalt intermediate course,
and 1.4 inches of asphalt surface course.
The pavement was resurfaced in 1980 with 2.9 inches
of asphalt and 0.7 inches of Open Graded Friction Course. In 1997,
contractors milled 1.9 inches from the surface and replaced it with 1.9
inches of asphalt and 0.4 inches of OGFC. There has also been some patching
to repair areas gouged by traffic.
Although the road was originally designed to
withstand the impact of 1.6-million Equivalent Single Axle Loads,
transportation officials estimate that the road has actually withstood the
effects of 12.5-million ESALS over the years.
“In many respects, we feel this pavement is not
special, but represents the typical long-lasting, low-maintenance flexible
pavements we have built for many years,” commented Tony L. Chapman, PE,
Acting State Highway Engineer. “Thanks to careful engineering, good
materials, and attention to quality, pavements like this have made South
Carolina one of the top-ranking states in Interstate condition...”
Texas Department of Transportation
 The
Texas DOT’s award-winning pavement is a section of northbound State Highway
173 in Bandera County, from State Highway 16 to the Kerr County Line. The
road, deep within the Texas Hill Country, is used primarily by ranchers,
vacationers, and people who enjoy a quiet country ride. Over 100-million
vehicles have used the highway since it opened 41 years ago. Today, its
average traffic count is 6,700 vehicles daily.
The highway was originally built with a 5-inch
flexible base and 0.5-inch two-course surface treatment. It was placed on
October 1, 1963. Since that time, it has required only one seal coat, which
was applied in 1987.
“When building this highway, we were able to take
advantage of some very good flexible pavement material sources in the area,
including limestone rock,” commented David Kopp, P.E., director of
construction for the Texas DOT. “In addition, the road was laid over a very
high quality subgrade. This has helped it last.”
Tennessee Department of Transportation
 The
Tennessee DOT’s award-winning pavement is an 8-mile section of Interstate 81
in the northeastern corner of Tennessee, mile marker 11.56 to 19.71. The
road opened in 1969 with an Average Daily Traffic count of 8,400 vehicles
per day. In 2002, the ADT was approximately 39,900 vehicles per day. Since
its construction, this stretch of Interstate has withstood an estimated
29-million Equivalent Single Axle Loads without any sign of structural
failure.
The pavement’s original construction included 8
inches of crushed stone base, 10.5 inches of bituminous base, 1 inch of
binder course, and 1 inch of surface course. The state overlaid one 3-mile
section with a 1.25-inch layer of asphalt in 1977 and spot-milled and
overlaid the same section with a 3.25-inch asphalt layer in 2002. A
different 5-mile section was milled and overlaid with 2.75 inches of
asphalt in 1989.
“I think there are several reasons this road has
held up so well,” said Gary Head, Civil Engineering Director of the
Materials and Tests Division of the Tennessee DOT. “First, for its time and
day, it had a very good crushed stone base — 8 inches of limestone. A good
base is vital to a good roadway.”
In addition, said Head, the design also used a large
stone base, which served as a conduit to allow water to get out of the
pavement. “This stone mix had a lot of stone-to-stone contact, which is
something that the industry is getting back to,” he noted.
Finally, the DOT successfully designed the pavement
to handle the loads it would carry in the future. “For this road, we
anticipated the right usage category and designed for it,” Head said.
Reprinted from Better Roads Magazine
June 2005 
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