|MEMORABLE Contractor chose to err on side of caution and rebuild portion.|
A contractor has demolished part of a new Florida bridge that sank 1 ft and twisted earlier this month, but officials expect to remain on schedule.
Steel crossbeams rolled as crews were moving concrete forms on Dec. 3, causing an 80-ft section of the new Memorial Causeway Bridge in Clearwater, Fla., to sink and twist. After assessing the situation and finding no structural damage, PCL Constructors, Edmonton, Alberta, decided to demolish the suspended roadway and steel supports.
"A small portion of the work wasn't carried out properly," says Jerry Harder, PCL vice president. Harder has said that "some of the components that were supporting the concrete" were engineered improperly. "We thought it was safest and quickest to remove it as opposed to trying to repair it, and that's what we've done."
William N. Nickas, state structures design engineer for bridge owner Florida Dept. of Transportation, says PCL encountered the structural problem with its cast-in-place span, which was a contractor redesign. "We [had] actually designed the bridge with travelers," says Nickas. "As a result of some movement, [PCL] decided it was safest to demolish the entire system, and not try to take it apart and put workers at risk."
The Dec. 18 demolition went as planned, according to Harder, who would not estimate how much extra cost the demolition added to the project. "We haven't even tabbed thatit's not really a big deal," he says.
The demolition ended with 1 million lb of concrete piled on top of a dirt mound that was meant to absorb the impact. The four-lane, $69.3-million project is expected to be completed in July 2004, as planned.
Part of State Route 60, the Memorial Causeway Bridge consists of twin cast-in-place segmental bridges spanning Clearwater Harbor between the City of Clearwater and Clearwater Beach. These bridges replace an existing bascule bridge that will be demolished when the new structures are completed. Each bridge consists of nine spans for a total length of 2,340 ft.
Of the nine spans, four originally were to be built by balanced cantilevers using form travelers, with the remaining five to be constructed on falsework. Two piers are accessible only by barge with the others accessible by land. The project was bid under the traditional design-bid-build process. But when PCL won the contract, it submitted a value engineering change proposal that changed the bridge designspecifically the drilled shafts, footings, columns and superstructure. This converted the bridge component to design-build.