March 10, 2011

In terms of sheer size, the I-185 rehabilitation project outside Columbus, Ga., is impressive enough.


Construction crews ran 24 hours a day, seven days a week, for just over a year, laying down nearly 660,000 tons of asphalt over more than 41 miles of highway.


But while other interstate projects may rival it in terms of size, few can match the results C.W. Matthews accomplished.


Getting started


In terms of sheer size, the I-185 rehabilitation project outside Columbus, Ga., is impressive enough.

Construction crews ran 24 hours a day, seven days a week, for just over a year, laying down nearly 660,000 tons of asphalt over more than 41 miles of highway.

But while other interstate projects may rival it in terms of size, few can match the results C.W. Matthews accomplished.

Getting started

The actual rehabilitation started on Exit 21 of I-85, which leads onto I-185, and continued 41.3 miles south to the Airport Thruway in Columbus. Most of the project was on four-lane rural highway, but a significant portion near the airport included six lanes.

Although the existing roadway was nearly flat, it was in extremely poor condition.

“It had been a good long time since they had done anything,” Mark Bartlett, C.W. Matthews project engineer, told Roads & Bridges. “There was actually grass growing up through the shoulders for most of the length of the job.”

Not only that, once work began, crews found that some of the shoulders were so shallow that they were actually hitting dirt. Many subsurface sections showed numerous structural failures. And at times, they had to patch deeper than the project specified because the original depths simply weren’t deep enough.

After performing the existing conditions survey, C.W. Matthews came through with a Roadtec RX 500, equipped with a 7-ft 2-in. drum, and milled the relief cut. Next, they used a Roadtec RX 900 with a 12-ft drum to make the final cut to grade.

Once a section was fully milled, a paving train, which utilized a Roadtec 2500 shuttle buggy feeding into a Roadtec 190 paver, laid down the hot-mix asphalt. Five different mixes were used during the process, including a 12.5-mm PEM mix, 12.5-mm polymer and 19-mm binder. A 12.5-mm mix was used on the shoulder, and variable mixes were used for patching and leveling.

Overall, C.W. Matthews used 25% reclaimed asphalt pavement (RAP). Obviously, tremendous economic and environmental benefits come with reusing such a significant portion of material. But Andrew Brooks, general manager of quality control at C.W. Matthews, credits the Georgia DOT’s progressive thinking for making the percentage fairly standard in the state.

“From a technical perspective, Georgia has been pretty proactive in terms of really trying to make use of the RAP,” Brooks told Roads & Bridges.

Unexpected issues

The project specified that each lane be milled to significantly different depths. Crews only had to mill 3 in. on the passing lane. But when it came to the trucking lane—and the middle lane in the urban section—the Georgia DOT wanted it to be milled 6¾ in. Not surprisingly, the main reason for the discrepancy was the structural deficiencies that the inside lanes had suffered from heavy trucking. Before the contractor could repave the highway, it had to mill those problems out.

But the two different depths posed a couple of challenges, one of which was entirely unanticipated. The design called for a 2% slope in the tangent sections, and it was difficult for crews to maintain the desired slope without reconstructing the shoulders, which would have cost time and money. What C.W. Matthews didn’t expect was the amount of water they had to deal with. Apparently that section of I-185 had been built through a swampy section of the state. And as workers began milling and paving, water started to seep in and actually breach the pavement.

“I don’t know what caused the water to come up,” Bartlett said. “Georgia was going through drought conditions that year, but there was water.”

However, C.W. Matthews settled on an innovative solution to the bewildering problem. To keep water from plaguing construction, workers staggered the joints. Otherwise, water would simply migrate straight up.

The sheer scope of the project made the work potentially overwhelming. Before a single traffic cone was put down, the contractor was meticulously planning every aspect of the job.

“We went out on our end beforehand and really planned out the job,” Brooks said. “And we started it by jumping in with both feet.”

Because the rehabilitation spanned more than 41 miles and required a staggering amount of material, C.W. Matthews couldn’t rely on one asphalt plant. Simple problems, such as running out of material or having quarries fail to keep up with production, were very real threats.

“Extreme communication was required with the asphalt construction end, the asphalt plants and the asphalt quality and control end to make sure that things were going smoothly without any hiccups,” Brooks said.

C.W. Matthews stayed in constant contact with the plants to make sure they could keep up with demand. They also made sure the plants stayed on top of the quarries to maintain the high production volume. If any new changes or challenges appeared on the horizon, the quality and control division informed the construction side so it could find a solution before any issues arose.

Each plant had different aggregate sources, so C.W. Matthews had to stay in constant communication to make sure they were calibrated to keep the mixes within a very tight range.

“If there were any issues on one end, we needed to be prepared to make whatever production changes were necessary to keep up with the laydown schedule,” Brooks said.

Pay day

The communication, the planning and the round-the-clock work all paid off, big time. C.W. Matthews started on Sept. 4, 2007. By mid-December, they had already milled and recycled 330,000 tons of material. And Brooks said those initial months immediately set the bar high for the rest of the work. Despite the incredible distance and unique challenges, C.W. Matthews was able to lay down all 660,000 tons of asphalt with no penalties.

Additionally, the project was substantially complete a whopping seven months ahead of schedule.

“At the time, they told us it was the largest resurfacing project ever let in the state of Georgia,” Bartlett said.

The final product was 36% smoother than before, but some of their accomplishments cannot be measured in percentages, dollars or time. Throughout the year-long job, which wrapped up in December 2008, C.W. managed to preserve the pristine landscaping that stretched for most of the rural segment of highway.

Although being a finalist for the Sheldon G. Hayes award is certainly an honor, Brooks is pleased that the team was able to deliver a highway that the state can be proud of.

“It’s impressive to look back and go, ‘wow, that really was just one job.’”

The night shift

While it may not have been as massive as the I-185 rehabilitation, the I-75 milling and resurfacing project in Sarasota County, Fla., presented its own unique set of challenges.

On the surface, it might not appear to stand out from the hundreds of other road projects that take place every year. Ajax Paving milled 2 in. along 13½ miles of six-lane highway and put back 2½ in. on the main line. Along the shoulders, the contractor milled out 1 in. and then replaced it. In all, about 60,000 tons of asphalt were used.

For a little more than 8 miles, they used 3?4 in. of OGFC FC-5 for the surface mix and 11?2 in. of SP 12.5 TL-E. For the remaining stretch, Ajax did a mill-and-replace using 3?4-in. Friction only.

But dig a little deeper and some truly impressive project details come out of the woodwork. The bid itself is even noteworthy. In order to win the contract, Ajax Paving had to make an A-plus-B bid, where prospective contractors bid not only on the cost but also on the time it will take to complete the job.

Most of the contractors bid about 180 days. Ajax upped the ante and cut the other bids in half.

“We bid 95 days, which also included a 30-day wait for final striping,” Mike Horan, president of Ajax Paving’s Florida division, told Roads & Bridges, “which means we had to have all the asphalt done in less than 60 days.”

All the work had to be done at night, between 8 p.m. and 6 a.m. This by itself is not unusual on interstate projects. But Florida threw a monkey wrench into the system.

“The problem is, here in Florida, they don’t let you reduce the speed,” Horan said. “So the speed has got to be maintained at 70 mph and you got your people behind cones. So it gets a little treacherous for our folks.”

Even though it had been nearly two decades since that section of highway had been repaved and was in dire need of resurfacing, the state did not want to create a miles-long bottleneck.

After the milling was complete, crews came through with a Rosc Ster L7500 tack truck to lay a tack layer down. Next, they followed with a Volvo 6160 paver. Four Sakai SW850 DD vibratory rollers and a Bomag BW11RH nine-wheel roller compacted the asphalt to finish the job.

Ajax Paving also did extensive testing to make sure the mixes passed muster. At the plant, five separate tests were done on the asphalt: FM 5-563 AC by Ignition Method; FM 1-T030 Superpave Gradation; FM 1-T209 Maximum Specific Gravity; and FM 1-T166 Bulk Specific Gravity Plant Gyratory Specimens Volumetrics. In the field they did an FM 1-T166 Bulk Specific Gravity of Roadway Cores test.

The tight deadlines and constant flow of traffic zipping by did not phase the workers, though. Despite the conditions, no one was injured during the project. And thanks to extensive field planning, Ajax Paving actually wrapped up construction with a day to spare.

Horan pins the project’s success on the planning and work ethic of everyone involved, including the subcontractors.

“We had to execute and get it done on time and we couldn’t trip up, which we didn’t,” he said. “When you put good subs with a good contractor, good things happen.”

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