Racking Up Smoothness BonusesTuesday, September 27th, 2011
Asphalt Contractor, September 2011
To win a Sheldon G. Hayes Award for asphalt pavement takes a commitment to quality by everyone involved. And it takes the right equipment, from the asphalt plant to the trucks to material transfer vehicles (MTVs) to the pavers. For the past 10 years running, eight of the last 10 Sheldon G. Hayes Award winners have used MTVs.
The most recent winner, Staker Parson Cos., of Salt Lake City, UT, won the award for work on approximately 8.5 miles of Interstate 15 in southern Davis County, UT. The project called for rubblizing three lanes of concrete in each direction, overlaying them with asphalt, and adding a new lane on each side in the median. Staker Parson worked night and day – and added crews to both night and day shifts – to meet an accelerated deadline and open the I-15 project in connection with an adjacent project.
Both the overlays and the new lanes required 7 inches of hot mix topped by a 1-inch open-graded friction course. Staker Parson laid down a base course of 2.5 inches, then applied two courses of 2.25 inches each. “We did use a Roadtec Shuttle Buggy for all paving,” says Brandon LeFevre, general manager for the contractor. “It definitely helped us with our hauling asphalt in belly dumps.”
Double-bottom belly dumps hauled asphalt to the grade and dumped it in a windrow in front of the paver. Using a windrow pick-up attachment made by Roadtec, the MTV picked up the windrow, remixed the asphalt to eliminate segregation, and transferred it to the paver. Easy, right?
Not so fast. It’s difficult if not impossible to back up the pup trailer pulled by a belly dump, so how can the paver deal with a gap in the windrow? No problem, if you have a Shuttle Buggy MTV. The big belly dumps can leave a gap in the windrow, dump as close as possible to the end of the previous windrow, and keep on trucking. The MTV ensures that the gap in the windrow is no problem and that the paver has plenty of asphalt.
“The MTV helped us keep a full head of material in the paver, and we could keep the paver moving,” LeFevre said. It was a high production project; Staker Parson was running at 300 to 325 tons per hour.
“We were really pouring on the coal,” said LeFevre. “We laid about 250,000 tons of hot mix asphalt, and we finished in seven months.”
Quality results were excellent. Staker Parson won 65 percent of bonus payments for smoothness, and 50 percent of the bonus payments for material quality, which was gauged by binder content, gradation and compaction. LeFevre said the MTV also helps with compaction, because it prevents thermal and physical segregation.
Lindy Paving Inc., New Castle, PA, has won the Sheldon G. Hayes award three times. And for all three projects, the contractor used a Roadtec SB 2500 Shuttle Buggy MTV. For all three, Lindy won smoothness bonuses. The lowest incentive was 79 percent; the highest was 91 percent, for the 2009 winner.
The 2009 award was given for Section 35M, a 6.6-mile stretch of Interstate 79 north of Pittsburgh.
The worn concrete roadway was designed to be cracked and seated. Antigo Construction used a guillotine hammer to crack the concrete at 24-inch intervals. Then the concrete base was seated with a 40-ton tow-behind, rubber-tired roller. Lindy paved a total of 18 inches of hot mix asphalt.
The Pennsylvania DOT starts its scale of smoothness bonuses at 60 inches per mile of deviation on the International Roughness Index. The highest bonus goes for 35 inches per mile or less.
“We hit 27.5 inches per mile on the northbound side, and 29.2 inches on the southbound side,” said Joe Conti, quality control manager for Lindy Paving.
Dan Ganoe, Lindy’s operations manager, said it’s important to maintain a consistent paver speed through a shift. For Section 35M, the contractor could pave from bridge to bridge within one shift, so no transverse joints were necessary. Distances per shift ranged from one to five miles.
“The MYV is an absolute necessity,” says Vince Tutino, president of Lindy Paving. “It provides for continuous paving, it prevents trucks from bumping the paver, and it remixes the asphalt to prevent segregation. Plus it affords faster delivery to the paver.”
Tutino said Lindy was one of the first, if not the first, contractor in Pennsylvania to use an MTV in asphalt paving.
“We had a Barber Greene remixer, then Roadtec came out with the Shuttle Buggy,” Tutino recalls. “Back in the early 90s we were one of the first contractors to use a Shuttle Buggy, even though it cost us more. Then within two or three years, Pennsylvania began to effectively specify a Shuttle Buggy, because they write the spec for segregation in a way that leads you to use one.”
MTV kept paver moving
Des Moines Asphalt & Paving Co., Des Moines, IA, has won the Sheldon G. Hayes award twice, once in 1998 and again in 2006. The contractor’s 2006 award was for a three-mile stretch of Interstate 235 in Des Moines. The contractor added a lane and a shoulder of full-depth asphalt to I-235, and paved three 2-inch lifts of asphalt on the adjacent two lanes of existing concrete. Then the entire width was paved with a 2-inch wearing surface running in both directions.
The project called for a new lane of pavement to be placed inside a temporary concrete barrier running the entire three miles. “The MTV was a necessity; there was no other way to get mix into the narrow tight median,” said Greg Kinser, vice president and operations manager for Des Moines Asphalt.
“We had to get mix to the paver inside the barrier rail,” Kinser said. “So we ran the MTV along the rail on the outside, and conveyed asphalt over the rail to the paver.” Kinser said the MTV also speeded production. “We would have had to add another truck or two to pave the same rate without it,” he noted.
A Six-Pack Astec asphalt plant supplied mix to the paver, which ran along at about 35 to 40 feet per minute. The plant could crank out 300 to 350 tons per hour.
“The MTV was a big help just to keep the paver moving,” says Gene Baloun, paving superintendent. “We hardly ever had to hold up the paver. The MTV was able to maintain enough material in it to give us some leeway with the trucks, so that we didn’t have to have a truck dumping at all times.”
Helps prevent thermal segregation
P. Flanigan & Sons Inc., Baltimore, MD, won the 2007 Sheldon G. Hayes Award for work on 16.8 miles of I-97 from Maryland 450 to I-695. Working at night because of heavy traffic on this route to the beach, the company milled and overlaid several sections of the road and the lengthy ramps servicing them.
Flanigan used an MTV for the entire project, and won smoothness bonuses. “The placer (Shuttle Buggy MTV) was a great help to us,” says Glenn Snyder, project manager. “You’re not waiting for trucks because it always keeps you moving.” The project required 60,700 tons of hot mix asphalt.
Duininck Inc., Texas Division, won the 2003 Sheldon G. Hayes Award for work on seven miles of southbound lanes on U.S. 287 in Wilbarger County, TX. The pavement consisted of a 4-inch overlay of 19 mm top-size aggregate mixture. That was surfaced with a 1-inch open graded friction course.
Duininck used an MTV on the project, and won 100 percent of the allowable smoothness bonuses. “And we won a substantial portion of the roadway density and laboratory density bonuses,” says Kyle Duininck, general manager of the Texas Division.
He said the MTV helps prevent thermal segregation, which is especially important in colder weather. What’s more, the MTV helps with projects where the paver needs a high volume of mix to lay down a thick lift. “If you’re paving with a heavy volume of asphalt, you can’t dump a windrow heavy enough to keep the paver going,” said Duininck. “But with a Shuttle Buggy, its capacity allows you to move a high volume of material to the paver over a short distance.”
A valuable, versatile tool
Norris Asphalt Paving Co., Ottumwa, IA, won the 2001 Sheldon G. Hayes Award for work on County Route P46 in Ringgold County, IA. Brady Meldrem, president and owner of the company, recalls that specs called for a 10.5-inch full-depth asphalt pavement to be placed over a rolled stone base. “I think we maximized our smoothness incentive,” said Meldrem. “And the MTV helped us to do that.”
Meldrem says by winning smoothness incentives – and by avoiding density penalties and the like – an MTV can pay for itself. The MTV helps achieve uniform density, because the mixture is the same temperature across the mat.
In summary, a product like the Roadtec Shuttle Buggy MTV is a valuable, versatile tool. It can pick up a windrow of asphalt and transfer asphalt over a barrier rail. It keeps your paver moving. It helps prevent thermal segregation, which leads to improved in-place densities. And it prevents physical segregation. As Vince Tutino says, it’s a necessity.