By: Bill Wilson
It’s the kind of road that wouldn’t even make a
squirrel stop dead in its tracks. Route P46 in Ringgold County, Iowa,
isn’t a haven for fast, confusing traffic. The road carries an average
daily traffic count of 360 vehicles.
The area tells the story of a farmer’s life. Hard work
produces quality product. Norris Asphalt Paving Co., Ottumwa, Iowa, knew the
words to this chorus all too well—and in the end earned the praises of
the entire asphalt industry.
During its 47th annual convention in San Francisco, the National Asphalt Pavement Association (NAPA) honored Norris’ flawless execution on a 61/2-mile stretch of Route P46 with the 2001 Sheldon G. Hayes Award.
It marked the second time the gold medal of the asphalt paving industry went to an Iowa contractor. In 1999 the plaque went to Des
Moines Asphalt & Paving Co. after its work on Iowa 141 in Dallas County.
Three years ago the Hayes Award was certainly in
Norris’ reach—the company took fourth place in the contest. Still,
President Brady Meldrem was a bit taken aback when the moment came.
“It feels unbelievable for a paving company such as
ourselves in the rural Midwest to be able to have that kind of honor,” he
told Roads & Bridges. “What it does for me, more than anything else,
is instill a huge amount of pride in the people I work with and that carry out
our company motto ‘We pave with pride.’”
The Hayes Award winner is determined through a two-year
process. Highway pavement projects using more than 50,000 tons of hot-mix
asphalt (HMA) are eligible for consideration.
Initially, they must win a NAPA Quality in Construction
(QIC) Award, which is determined by numerical scores given by pavement
engineers at the National Center for Asphalt Technology, Auburn, Ala., on the
basis of how well the contractor met the specifications and achieved density on
the finished pavement. All the pavements meeting a benchmark figure are given
the QIC Award.
A project may be considered for the Hayes Award the year
after it wins a QIC Award. The top-ranked projects are tested for smoothness
then visually inspected by an independent pavement consultant.
More responsibility
Throughout much of the 1990s, Ringgold County roads bathed
in concrete. In fact, the Route P46 project was originally planned for the
white pavement.
“When I took over in 1998 my predecessor had done the
grading portion of the job and had planned to do a concrete road,” Brian
Moore, engineer for Ringgold County in 2001, told Roads & Bridges. “I
looked at the option of concrete vs. asphalt and came to the conclusion that a
full-depth asphalt job for the amount of traffic on the road and the amount of
money we were talking about was the best option.”
Asphalt is now a legitimate option in Iowa, thanks to the
state’s Quality Management Asphalt (QMA) Program, which ultimately holds
the contractor responsible for the quality of the product. The program requires
every 500 tons of produced asphalt to be tested for asphalt and void content.
Cold feed samples at the plant also are taken twice a day to monitor cold feed
gradations and moistures.
“It’s really kind of a unique partnership
between the state and contractors,” said Moore. “That program has
elevated the quality of the work that is being done.”
“In years past the state had always been the one to
designate what the job and mix design was and all the testing,” said
Meldrem. “This program forced us to be more intelligent about our
product. It forced us to train and learn more . . . and so now the contractors
are the experts in the industry about mix design and what needs to go down on
the road. We can now go to them and say, ‘Tell us what your concerns
might be because we can tell you how we’ve addressed that as far as the
mix design.’”
Norris Asphalt Paving had the county convinced when it came
time to awarding the 61/2 miles of Route P46. According to Meldrem, the
location was “anywhere from 75-80 miles away from concrete stone.”
Local material was available to produce a good asphalt mix.
“We were able to put together some mix designs that
gave the county a good product with more locally available materials,”
said Meldrem.
Per QMA specs Norris Asphalt Paving comes with a full lab
and two lab technicians who do nothing but monitor the product being placed.
The team ran about 6-8 tests a day during the 121/2-day life of the
project, which cost a little over $2.2 million. Construction started in May
2000 and concluded in June.
“We had a quality control staff available to work with
the county,” said Meldrem. “The county could come in, monitor our
work and ask questions about the testing.”
An urban resetting
Despite the country surroundings, Route P46 was anything but
a sit-and-pave achievement. The new two-lane road—30 ft wide including
6-ft gravel shoulders—consisted of a 1,500-ft-long urban section where
there was a livestock exchange and cemetery adjacent to each other. Farmers
wanted access to the sale barn, and county officials aimed to maintain the
integrity of the cemetery.
“We were very concerned about the livestock
exchange,” said Meldrem. “They hold about two events weekly that
are huge. There’s a lot of traffic, farmers coming in and out.”
To accommodate the action the existing grade was raised 8
in. and about 3,000 ft of curb-and-gutter was in-stalled. A small amount of
sewer work also was conducted. The storm sewer had to be extended to intakes in
the new curb for drainage purposes.
For the cemetery, crews made a vertical cut into a bank and
installed a 12-ft-high, 300-ft-long Allen block-type retaining wall.
“We worked with the city to get the urban section they
wanted,” said Moore. “We widened the pavement, but yet we had two
obstacles—cemetery and livestock auction—on either side that
couldn’t move. We had some spatial constraints there. That was the
biggest challenge.”
Both the rural and urban parts called for a pavement
thickness of 101/2 in. Norris Asphalt Paving laid HMA over an existing
rolled stone base on the rural section. The urban section included the
full-depth design and something extra. In the area of curb-and-gutter a 4-in.
overlay was placed.
The full-depth pavement contained four different
lifts—41/2 in. of base course, 21/2 in. of binder course,
another 2 in. of binder course and a 11/2-in. surface layer.
The base mix (3/4 in. Iowa Type B), which included the
binder layers, was made up of 51% 3/4 in.-to-dust product, 10% manufactured
sand, 28% coarse natural sand and 11% fine natural sand. The asphalt content in
the base was 6.1%. On the surface (1/2 in. Iowa Type A) there was 15.5%
3/4 in. clean product, 49.5% 1/2 in.-to-dust product and 35% coarse
natural sand. The asphalt content was 5.9%. The asphalt cement used in both
mixes was PG 58/-28.
A Gencor 400 tph portable asphalt plant, set in a quarry
location about 41/2 miles south of the project, generated 380-420 tph to
14 RD Series Mack trucks. A total of 51,700 tons of asphalt was used on the
project.
Trucks hauled the product to a Roadtec Shuttle Buggy, which
transferred the material to a Cedarapids 551 Grayhound rubber-tired paver.
Traveling at an average of about 30 ft per minute (20-25 ft per minute for the
base, 45 ft per minute for the surface), the Grayhound paved 12-ft lanes laying
asphalt down at about 305°F. Leading the roller train was an
Ingersoll-Rand DD110 HF double-drum vibratory machine. The intermediate roller
was a Caterpillar pneumatic rubber-tired PS180, which was followed by a static
steel double-drum Sakai S850. The VPM on the I-R DD110 HF was 3,600.
A slight adjustment was made during the first day of paving.
The crew was a little short of its 31/2% air void goal and immediately
made some minor aggregate gradation adjustments. “Everything worked like
clockwork after that,” said Meldrem.
The required average road density was 94%. Norris Asphalt
Paving achieved 97.4%.
“This asphalt is performing extremely well,”
said Moore. “Other than natural fading over the course of the year it
looks as good as the day we walked off the job. The ride is as smooth as the
day we quit paving. I attribute that to the quality of mix that was used, the
mix design and the quality of construction. It was a matter of blending the right
local product.”
