The Monumental Cooper River Bridge

$540 Million Cooper River Bridge Design-Built in 48 Months

by Scott Judy

The newly built, $540 million Cooper River Bridge in Charleston, S.C., has attracted attention and admirers from around the country, some of whom have called the final result "tremendous," "pretty spectacular," "impressive" and "very attractive."

One of the workers building it boasted to Engineering News-Record that it was "the greatest bridge in the world." And it's the best recent example of what's right and even great about construction.

Like other iconic structures, the newly opened bridge - featuring the longest cable-stayed span in North America - stands as a monument to not only construction, engineering and design excellence but also to more basic elements such as communication, perseverance and, perhaps most notably, a major effort to better the lives of local residents. (The American Road & Transportation Builders Association recognized the project with its top national PRIDE Award for Community Relations for the construction team's community outreach efforts. In full disclosure, this editor served as a judge.)

Indeed, for Bobby Clair, director of engineering for special projects for the South Carolina Department of Transportation, and Wade Watson, senior project manager for Palmetto Bridge Constructors - and for hundreds of others - this has been a once-in-a-lifetime endeavor. That's because the task was more than just building a massive, iconic structure in a quick time frame.

The team also had to build it to withstand a Category 5 hurricane, an earthquake measuring 7.3 on the Richter scale, plus any impact from some of the world's largest cargo ships.

Also setting it apart was the cost. Its total price of $644 million - including right-of-way and other items - was more than double the state's entire annual construction budget. That meant cost overruns were absolutely unacceptable.

Moving Forward

The Cooper River Bridge project has won kudos for how smoothly it has progressed - despite the fact that this was one of SCDOT's first few design-build contracts, not to mention far and away the agency's largest project ever.

William R. Cox, state bridge engineer with the Texas Department of Transportation, who visited the jobsite last year, was impressed with how well the team had been able to progress, despite the complexities of the project. "It was one of those projects that had the potential to have lots of rocks in the road," he said.

Instead, not one claim has been filed between PBC and SCDOT, and the contractor was set to finish a month ahead of its own schedule - and 13 months ahead of the state's - and the budget was close to where it had been when work started.

For this project, being on schedule was a major accomplishment in itself. That's because Palmetto Bridge Constructors - a joint venture between majority partner Tidewater Skanska of Norfolk, Va., and Flatiron Constructors Inc. of Longmont, Colo. - won the job with a proposal that called for a four-year schedule instead of the five years SCDOT had originally allocated.

"That comes with pain, of course, because to build it that quickly you have to put more resources into it," said PBC's Watson.

"As much resources as we had in the job, and as much overhead, and as large of businesses (Skanska and Flatiron) that we have here, there are huge costs. Looking at that compared to the construction costs, we just thought it was cheaper to push the job."

So they did. The design-build contract was signed in July 2001, and the first test pilings were being installed by January. By mid-2002, about 300 workers were on the job, and by the end of '02 an estimated 600 were onsite. By project's end, an estimated 40 cranes had been utilized.

Luck, Good Timing

As late as a few weeks before signing the contract, funding was still unresolved. As built today, the new, 3.5-mi.-long bridge features eight traffic lanes, two breakdown lanes, plus a 12-ft. pedestrian path. When it was being bid, however, SCDOT was keeping its options open.

"We didn't know until weeks before we signed the contract that we actually had enough money" to build the bridge standing today, Clair said. He added that a $215 million state loan "came in at the last minute" to supplement a $325 million grant from the state infrastructure bank.

To accommodate the funding uncertainty, SCDOT required contractors to provide options for a four-lane bridge with a foundation to accommodate a second four-lane bridge sometime in the future.

"When we got the (proposal) packages in, we were pleasantly surprised that they came in low enough that we could add in everything," Clair said.

Also notably, SCDOT's timing was lucky. Carr said that if the project started today and had to deal with the recent spike in materials costs, another $200 million would be added to the price of construction - perhaps making such a grand bridge beyond the agency's grasp.

Slow Start to Design

Finalizing design was the next hurdle.

The bridge's foundations were a critical component, and early on there were issues with their design. PBC and SCDOT worked through the issues with bridge designer Parsons Brinckerhoff of New York, who was contracted to PBC as designer of record. SCDOT contracted with a joint venture of HDR of Omaha and San Francisco-based T.Y. Lin International for design review and inspection.

"The internal design complexities change with the seismic requirements, the wind and the ship collision impacts," Clair said. "If you build a bridge like this over a canyon somewhere that has none of those features, you've eliminated all of that real complex design."

With so much riding on its decisions, the team had trouble reaching conclusions.

After three months of discussion, Clair had had enough. One Thursday afternoon, he called the designers and told them to be at the Charleston jobsite the next Monday at 8 a.m. A decision was going to be made.

Within 10 minutes of finally getting the two consultants in the same room, the team reached a conclusion. Clair added that from then on, the parties involved in any meetings involving design matters would work until the issues were resolved.

Unique Complexities

Foundation issues were just the beginning. Clair and Watson and their team of designers would travel to Canada for scale-model wind-tunnel testing, as well as to Denmark for ship-impact tests. They also visited San Diego and New York City several times for seismic issues.

The wind-load testing was especially complicated, and the project's capability of withstanding a major seismic event - a characteristic that is built into the bridge's foundations, deck, support towers and other components - also required extensive computer modeling.

The state's seismic code - which is just as strict as 80 percent of the state of California's; some locations there are more stringent - "affected the design drastically," Watson said.

"On the one hand you want strength in the bridge for ship impacts and resistance to hurricane-force winds," he said. "Seismically, you want flexibility. You want it (to be able) to sway in the same direction. If things go in the opposite direction, spans fall out. So it's a balance between strength and flexibility."

To accommodate flexibility, the towers include plastic hinge zones. A damping system was added to ensure the ability to withstand 190-mph hurricane-force winds. A tiedown system was also incorporated during construction for wind events.

"Once (the model) is tuned, then you're pretty well stuck with it," Watson added. "You can't change anything - the rebar or strength of concrete. All of those things (and more) drastically affect the seismic constraints."

Computer modeling magnified the bridge's reactions to wind or seismic events by about 50 times. Wind-tunnel testing continued after the start of construction, and lasted for about one year. After this testing concluded, the project team continued to monitor on-site wind conditions for approximately another year.

A Bridge - and More

The 1,546-ft. main span hangs from two "diamond-shaped" towers, with 128 individual cables anchoring it to the hollow interior core of the 575-ft. tall structures. The deck is approximately 200 ft. above the median high-tide mark.

This was the critical path. Watson said PBC crews worked six days a week, with two 12-hour shifts, during the erection of both the towers and the main-span deck. The towers were built with cast-in-place concrete, while the main-span deck consists of structural steel framing and precast concrete panels constructed and barged in from Savannah, Ga. A latex concrete overlay is then applied over the precast panels.

The cable stays on the main span are state-of-the-art and have been studied by several other state DOTs. TxDOT's Cox said he was impressed with how the technology has improved since his state last built such a bridge 12-15 years ago.

Instead of a grouted stay, Cooper River's stays are wax-coated and sheathed in a polyethylene material. Also, maintenance issues are minimized because individual cables or wires can be replaced if any corrosion or other problem occurs. Overall, Cox described the system as "very robust and very well-suited for corrosive environments."

A single cable - which can hold more than 1 million lbs. - is composed of as many as 90 seven-wire strands twisted together. The protective white polyethylene pipes range in diameter from 12 to 20 in.

Both the tower and deck erection "went without a hitch," Watson said.

Overall, the project is so massive that PBC broke it up into five main components: the main span, two high-level approaches - together measuring 2.5 mi. long; and the two interchanges on either side. Surface street work was yet another separate effort.

"Breaking it up into something more manageable worked pretty well," Watson said. "Each of those five areas had a dedicated schedule and they all came together at the same time."

Community Project

Like other federal-aid highway projects, the Cooper River Bridge contract required the contractors and DOT to provide on-the-job training opportunities. But the team took this requirement and incorporated it into a broader community outreach effort.

"Just to assemble that program took six months," Watson said.

The project team recruited more than 80 unemployed, underemployed and homeless citizens.

Program participants started with approximately two weeks of paid "lifestyle training," as Clair called it. Topics included basic job performance, personal financial management and childcare, among others.

After that, they could start the on-the-job training for various trades such as welders, carpenters, concrete finishers, asphalt surveyors or equipment operators. Approximately 62 of the recruits eventually were able to obtain journeyman status.

The community input was sought partly due to the impact of the Charleston interchange on local residents. This four-level interchange itself cost one-third of the project's overall price and would impact six different neighborhoods, including more than 30 residences, roughly 16 businesses, five churches and two nonprofit organizations.

"We had to build that interchange in a minority, low-income neighborhood where people were already impacted in some way (from the existing bridges) and we were going to impact them even more," Clair said. "We had to bring the community onboard."

The elimination of the old bridges is expected to spur future development in the area.

The DOT and contractors went further than they were required in other ways. When they found out a local school didn't have a paved basketball court, Clair and Watson solicited donations of surveying and concrete and provided free labor to provide the court at no cost.

The project team also donated $7,040 to four neighborhood elementary schools, along with two computers for each.

Additionally, the project provided $20,000 in college scholarships - two $2,000 scholarships per year for five years - to students from the impacted area pursuing transportation-related degrees.

The SCDOT also established a four-week "Summer Transportation Institute" for high-school freshmen and sophomores to learn about transportation infrastructure and to improve their computer, math and writing skills. It also provided 20 scholarships for students in the impacted community to attend the institute.

End Result

Not everything went perfectly. Clair and Watson admit they didn't always agree, and some mistakes were made. SCDOT officials admitted to their peers that the agency could have done a better job preparing the contract's performance specifications, said Hossein Ghara, state bridge engineer with the Louisiana Department of Transportation and Development. Ghara has viewed this project carefully because Louisiana is beginning design-build construction of a $200 million cable-stayed bridge across the Mississippi River at St. Francisville.

Performance specifications for a design-build contract are different than a standard project, Ghara said, and that was the issue.

"Part of the problem was they (prepared the specs) in a hurry because they were under pressure to go on with construction and yet they were trying to bring it within their budgetary constraints," he said. "For the connection splices, the specifications did not require the contractor to use load-indicator washers. So the (contractor) was not going to use them because they're more expensive."

Eventually a compromise was reached.

Ghara, who called the bridge "very attractive," nevertheless said the design-build approach had worked.

"It brought down the costs drastically by doing it design-build," he added. "Granted, when they did it the construction prices were much more manageable."

Paul V. Liles, state bridge and structural design engineer with the Georgia Department of Transportation, had nothing but praise for SCDOT's first steps into design-build.

"The amount of time from start to finish is really impressive," Liles said. "Tidewater Skanska put together a tremendous design-build team and they worked very diligently straight on through the project. So the delivery of the project has been tremendously impressive. They accomplished it just very beautifully."

Nearing the end, Watson said it had been an all-consuming effort for everyone.

"With a job like this, you don't get to go home, go to sleep and forget about it," he said. "It's going on all the time, day or night, weekends. We set dates and deadlines, and hell or high water we make it happen."

Clair summed up the feeling at the project's conclusion.

"We're all real proud of where we are today," he said. "I think history will show what's been accomplished here."