Saving time
Lanes added to Alabama stretch of I-20 under heavy traffic

By Sandra Bearden

A job must finish on time, so John Brown of Good Hope Construction Inc. of Cullman, Ala., paid attention when a subcontractor said it could shave time off an essential step in the $25.6 million widening of Interstate 20 between Pell City and Riverside, Ala.

"Sherman Dixie Concrete Industries proposed we use precast inlet boxes rather than poured-in-place inlets under the median barrier walls," said Brown, Good Hope's vice president-operations. "There was one hitch. The Alabama Department of Transportation's drawing books didn't include the inlets. So Sherman Dixie's engineers prepared drawings, submitted them to ALDOT and got them approved.

"Using the inlets has saved us time on that phase of the job and put us days ahead of schedule."

Good Hope began work on the 4.3-mi. project in July and expects to finish the job in July 2006. Federal money is financing 80 percent of the contract and state funds are underwriting the remainder.

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Already nationally certified to fabricate precast concrete products, Sherman Dixie of Cullman began production quickly, trucking six inlet boxes daily to the construction site. Each 9,000-lb. inlet is 3 ft. wide, more than 6 ft. long and 5 ft. deep.

"Instead of spending time erecting inlet boxes, tying steel, pouring the concrete and waiting for it to cure several days, Good Hope workers were able to concentrate on building the roadbed," said Dewayne Shaddix, sales representative for Sherman Dixie.

J. F. Horsley, Birmingham division engineer for ALDOT, said the biggest task has been performing the work while not interfering with traffic flow.

"We're expanding a whole stretch of I-20 from four to six lanes in each direction," Horsley added. "Although there are temporary tie-ups, we basically try to keep four lanes open all the time. Between 40,000 and 45,000 vehicles travel the road daily in the part of the interstate we're working on. That volume increases as you get closer to Birmingham."

To keep traffic flowing, the highway department designed the project so that traffic could be shifted 7 ft. onto the outside shoulders. After completion of median lanes and barrier walls, traffic will shift onto the two new inner lanes, enabling workers to pave the outside lane.

Specially formulated Superpave asphalt is being placed over the roadway's existing concrete pavement, which is being rubblized. During the rubblization, subcontractor Resonant Machines Inc. of Tulsa, Okla., is breaking the existing concrete pavement with a guillotine breaker, which turns the concrete into road base material for the new asphalt surface.

Good Hope first paved the outside shoulders in order to shift traffic, then brought in fill material and paved the median to bring it higher than the existing concrete.

"At that point, RMI is performing the rubblizing in three stages," said Malcolm Douglas, project manager for Good Hope. "With traffic on the outside, they're rubbilizing a narrow 8-ft. strip on the inside so we can pave the median and overlap the existing roadway. After we shift traffic, they'll rubblize another strip. Then we'll do the remaining outside lanes in the last phase."

The company will lay 1 ft. of asphalt on top of the rubblized concrete. A multi-layered median, with a bottom layer of crushed aggregate and numerous layers of asphalt, is 2 ft. deep.

"Pavement thickness primarily depends on soil conditions and truck traffic," Douglas said. "While the soil is generally good, a large number of heavy trucks travel this road, so we need the 2-ft. buildup in the median."

A paving crew of 12, directed by Good Hope's area manager Jim Chambers, is constructing three 12-ft. lanes on each side of the interstate. The total width of the interstate, including the median's barrier walls and shoulders, is 121.5 ft.

Good Hope is hauling 260,000 tons of asphalt from its nearby Ashville plant for the project.

While paving is under way, subcontractor Alabama Bridge Builders Inc. of Pelham, Ala., is working on three bridges. Douglas said that work on one bridge was performed early in the project to facilitate traffic flow.

"We had to raise the overpass bridge at Riverside exit early in the project so we could shift traffic out onto the shoulders," Douglas added.

"We needed to make sure vehicles wouldn't hit the girders because the bridge girders curve a little at the shoulders. Raising the bridge also helped us maintain the proper clearance since the interstate is being raised."

Robert Earley, secretary-treasurer of Alabama Bridge Builders, said lifting bridges that span interstates is business-as-usual for his firm.

"We hook multiple jacks together in one system," Earley said. "A hydraulic pump supplies fluid to all those jacks at the same time, and the jacks lift the bridge up in increments of .5 to 2 in. As we jack up the bridge, we put steel plates underneath.

"When we've raised it 20 in, the plates are holding up the bridge. Then we pour concrete around the base. We just have to be careful and not tear up what's already there."

Alabama Bridge also connected two I-20 bridges that cross a county road and railroad tracks.

"There was a gap of about 35 ft. between the lanes of traffic," Earley said. "We added new supports and substructures and widened the decks over new girders so we could add the median barrier walls."

Douglas said there are more than 22,000 lin. ft. of 54-in.-tall concrete safety barriers that are being slip-formed the entire length of the project to separate east- and westbound traffic.

"Alabama Slipform Inc. of Birmingham constructs the barricades and lays out reinforcing steel to support the walls," he added. "It also adds empty conduits under the walls to add lighting if it's needed later."

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