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Cover Story — September/October 2005

A Graceful Link

North America's longest cable-span bridge opens in Charleston, S.C., just four years from award of the initial contract

By Debra Wood

The diamond shape of the towers, chosen by the community, gives the bridge its signature.

Historic Charleston, S.C., now has a landmark northern gateway with the summer opening of the newest bridge over the Cooper River. Four years after receiving the green light, its design-build contracting team finished construction on Charleston's 3.5-mile, $540-million Arthur Ravenel Jr. Bridge for the South Carolina Dept. of transportation. The eight-lane bridge is the longest cable-stayed bridge in North America.

The bridge over the Cooper River opened to traffic in mid-July after a week-long community celebration.

"It's a monument that will be here forever," says Wade Watson, project manager for Palmetto Bridge Constructors, the design-build joint venture of Tidewater Skanska Inc., Virginia Beach, Va., and Flatiron Constructors Inc., Longmont, Colo. "It's built to withstand anything that can float in the water." It is designed to withstand Category 5 hurricanes, an annual threat, and major earthquakes such as the one that decimated the city in 1886.

Palmetto Bridge Constructors self-performed 80% of the work. At peak construction, 600 PBC employees and 200 subcontractors worked on the 3.5-mile-long bridge and its access roads.

"We had to have a strong, robust bridge and it had to be flexible and able to bend and move and remain standing," says Bobby Clair, SCDOT director of engineering and special projects. "Blending that together created a real issue for the designers."

PBC selected Parsons Brinckerhoff, New York City, as a design partner. San Francisco-based MacDonald Architects consulted and suggested eye-appealing features such as sloping light poles on approaches to the bridge to match the cables' slope. The firm also suggested slanting piers to echo the diamond shape of the bridge's two towers, which anchor the cables that support the road deck.

"Even though this was cost-driven, we were able to include a lot of nice architectural features to enhance the look of the bridge," says Michael Abrahms, technical director of major bridges for Parsons Brinckerhoff.

SCDOT considered a wide variety of solutions to replace the aging and narrow John P. Grace Memorial and Silas M. Pearman bridges, including a tunnel, but environmental impact studies favored a single bridge.

SCDOT consulted with neighboring communities during planning and the public chose the signature 575-ft-high, diamond-shaped towers. That added a degree of difficulty to the job, Watson says.

The bridge's 1,546-ft main span is supported by two 575-ft-high, diamond-shaped towers.

TYLI/HDR, a joint venture between T.Y. Lin International's Alexandria, Va., office and Omaha-based HDR, provided design review, engineering and inspection services for SCDOT.

Design-Build

At a total cost of $632 million, the bridge represents the largest single transportation infrastructure project completed by SCDOT. It is 2.5 times the department's annual statewide construction budget. At the job's beginning, when the state was ready to proceed with bids, it did not have all of the funds to complete the structure.

"We thought we could build four lanes, and if we came up with the money during construction, we could probably do the other four," says Clair. "But by doing design-build, we could set the wheels in motion."
SCDOT moved forward with the help of a $325-million grant from the South Carolina Infrastructure Bank, established in the late 1990s. The bridge's namesake, state Sen. Arthur Ravenel, spearheaded campaigns to create the bank and build the bridge. At the last minute, the state secured a 25-year federal loan for an additional $215 million, allowing it to proceed with all eight lanes, ramps, a frontage road and bike and pedestrian lanes.

Project Details

Grand opening: July 16, 2005
> Connects Charleston and Mt. Pleasant along Highway 17
> Eight 12-ft-wide traffic lanes
> 1,546-ft main span
> 575-ft-tall towers
> Road deck rises 200 ft above the median high-tide mark
> 128 individual bridge cables
> Cables formed by 90 seven-wire strands
> Each cable holds more than
1 million lbs
> White pipes range in diameter from 12 to 20 in.
> 12-ft bicycle and pedestrian lane
> 300,000 cu yd of concrete
> 50,000 tons of reinforcing steel
> 40,000 tons of structural steel
     > More than 400 drilled shafts

Clair, Watson and Abrahms say that the design-build approach worked well but had its risks.

"It's wonderful, great for the owner, but it puts a lot of risk on the contractor and makes the job more difficult because you are trying to procure and build while design is still going on," Watson says.

Design-build also changes the design dynamics tremendously, Abrahms says. "In the past, you worked with a government agency and made decisions with the agency," he says. "Now, all of a sudden, someone else, the contractor, is at the table and he tends to have a lot of opinions."

But Abrahms also sees the positive. "It allows the owner to select what he thinks is the most well-qualified team," he adds. "I think that benefits the industry."

SCDOT employed a formal partnering program on the job. Senior management met every three months at retreats to address anticipated problems. Managers responsible for each issue reported back at the next meeting.

"We stayed until we had a solution to every problem," Clair says. "On most of the design issues, there were great discussions and debate. When video and teleconferences weren't working, I would call an onsite meeting, and we'd sit down face to face and find out what the issues were. Seldom did it take more than an hour to work out the details."

The cable anchors connect the 128 individual bridge cables to the bridge deck. Each of the cables was formed by 90 seven-wire strands and can hold more than
1 million lb.

Construction

PBC received the notice to proceed on July 16, 2001, with a contract completion date of July 2006. But PBC had a plan to build it in four years, not five, decreasing the cost of overhead.

"We split the project into five jobs-each interchange, each high-level [approach] and the main span," Watson says. "There were five budgets, five schedules, five sets of equipment and five sets of supervision. We had very little overlap and ran five simultaneous $150-million construction projects."

Demolition of homes began in fall 2001 and the first foundation work started in April 2002. Design called for a drilled-shaft foundation, chosen over pile driving to decrease noise for nearby residents and create less disturbance to the existing bridges. The site had soft soil, forcing crews to drill 240 ft to a deeper clay layer. Some of the shafts are 12 ft in diameter.

Steel girders on the high-level approaches sit atop a series of columns and pier caps. Concrete girders were used on the interchanges.

The 1,546-ft main span hangs between the diamond-shaped support piers by 128 cables, which are made of seven-wire strands twisted together and enclosed in a high-density polyethylene pipe. The pipe ranges in diameter from 12 to 20 in.

PBC self-performed 80% of the work. At peak construction, 600 PBC employees and 200 subcontractors worked on site. PBC hired as many locals as possible before bringing in people from outside areas.

"It's a monument that will be here forever. It's built
to withstand anything that can float in the water."
                  — Wade Watson, Project Manager,
                                   Palmetto Bridge Constructors

Community Involvement

"We spent a lot of time with the community in public relations and did things to lessen the impact of construction," Clair says. "They supported us all the way through, and that was a big part of the success of the project."

The bridge decks, which rise 200 ft above the median high-tide mark of the Cooper River, contain more than 300,000 cu yd of concrete.

The bridge displaced residents of a low-income neighborhood, and SCDOT officials included in the contract a requirement to train local residents in building trades. PBS provided a two-week course to teach job-readiness skills and safety to 82 unemployed or underemployed residents, then offered on-the-job training in crafts. Sixty-two of the people obtained journeymen's status in at least one job area.

"We exceeded the state's goal," Watson says. "And had some good success stories."

New hires, working in the special program or just new to the jobsite, wore a hard hat with a green stripe that let foremen know to send an experienced hand for certain tasks. Workers strove to prove they knew the safety rules and earn the removal of their stripes. The team also used incentives and training to promote safety. The bridge was completed within budget, with no claims or issues between PBC and SCDOT. It opened as scheduled on July 16, after a week of special events.

"I was excited to be here, in my home state, building a significant bridge, a landmark bridge," Watson says. "It was a very challenging project, and something I am proud to be part of."

The $632-million, eight-lane bridge, which connects Charleston and Mt. Pleasant along Highway 17, is the largest single transportation infrastructure project ever completed by the South Carolina Dept. of Transportation. It cost 2.5 times the department's annual construction budget.

Project Team

Owner: South Carolina DOT

Designer: Parsons Brinckerhoff, New York

Design Review and Inspection: TYLI/HDR, a joint venture between
T.Y. Lin International, Alexandria, Va.; and HDR, Omaha, Neb.

General Contractor: Palmetto Bridge Constructors (PBC), a joint venture of Tidewater Skanska, Virginia Beach, Va.; and Flatiron Constructors Inc., Longmont, Colo.


 

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