Tampa's Elevated Connector Tests the Team
An elevated Tampa toll road with 23 spans, a tangle of flyovers and unexpected foundation issues is challenging the project team, while it is also revealing the limitations of contractor-obtained financing. The 65%-complete job, currently estimated at $412 million, instead of the original $389 million, is now expected to finish up next fall, or about six months later than originally planned.
Designed to boost the Port of Tampa, the 12-lane Tampa Interstate 4/Selmon Expressway Connector involves constructing a 1.1-mile north-south toll road to link the east-west I-4 and the expressway. The project is in part a response to the expansion of the Panama Canal, which port officials say will deliver "significant new trade opportunities" to Tampa.
"The I-4/Selmon Expressway Connector will provide a vital connection between two of the most important surface transportation facilities in the region," says Richard Frank, construction project manager with the Florida Dept. of Transportation (FDOT).
Despite its perceived economic importance, the connector remained just an idea until the economic downturn. But thanks to the 2009 American Recovery and Reinvestment Act, Tampa-area transportation officials pushed the languishing plan to the top of their stimulus-package wish list. By the time an industry forum was held in May 2009, the project-owner partnership, which includes FDOT, Florida's Turnpike Enterprise and the Tampa-Hillsborough County Expressway Authority, had dusted off plans and announced that more than $105 million in stimulus money, coupled with $298 million in contractor-obtained financing, would largely fund the design-bid-build-finance project.
Going in, the main challenge appeared to be the project's tangle of flyovers at each end. FDOT offered bidders four designs to consider. Working with the engineers, the winning joint venture of PCL Civil Constructors and Archer Western Contractors (PCLAW) decided the most cost-effective option was the mix of 12 precast bridges and 11 bulb-tee girder structures.
The first problem surfaced soon after work began in March 2010. Initial pilot borings for some of the more than 1,100 drilled-shaft foundations revealed inconsistent subsurface bearing conditions, thanks to pinnacle limestone formations.
The conditions affected some of the 36- to 90-in.-dia foundations, designed with typical depths of 65 to 70 ft. The south end of the connector project, near the Selmon Expressway, was the most troublesome.
"There are a lot of unforeseen conditions," says Greg Fullington, PCLAW's lead project manager. "In the same footing, we'd have a shaft that went down 50 ft and 4 feet away the depth would be 120 ft," he says.
Crews cast the concrete shafts using temporary casings. Still, there was difficulty thanks to the subgrade's high porosity. In some instances, once the casings were removed, the concrete filled the voids, resulting in significant head loss in the shaft. After a few of these instances, PCLAW crews stood ready to recharge shafts with extra concrete, if needed.
A.H. Beck Foundation Co., San Antonio, had expected to complete two drilled shafts per day. The pace was often half that, says Fullington.
The extra time and labor required for the shafts has added about $5.8 million to the project's cost. PCLAW says it will seek reimbursement from FDOT under a supplemental agreement.