Highways/Bridges Best Project: Choctawhatchee Bay Bridge (US 331)
Choctawhatchee Bay Bridge (US 331)
Walton County, Fla.
Owner: Florida Dept. of Transportation
Lead Design Firm: Parsons Brinckerhoff
General Contractor: Skanska USA
Civil/Structural Engineer: WSP - Parsons Brinckerhoff
Geotechnical/Environmental Engineering: Madrid Engineering Group
One in a series of projects aimed at expanding U.S. 331 to four lanes from two, the $118.5-million Choctawhatchee Bay Bridge project delivered a new 2.5-mile crossing over a sensitive marine environment. Built alongside the existing two-lane Clyde B. Wells Bridge, the new structure now serves as U.S. 331’s northbound lanes.
The bridge is founded on 30-in.-sq piles measuring 80 ft to 160 ft in length with cast-in-place concrete footers and columns. The design called for a mix of hammerhead caps and precast-pile and precast-cap construction. The spans, which ranged from 142 ft to 200 ft in length, consist of 72-in. and 96-in.-deep Florida I-beams, cast-in-place deck with galvanized stay-in-place deck forms, a post-tensioned channel span and mass concrete substructure.
To help protect the bay, which is home to such endangered species as the giant gulf sturgeon and the Oskaloosa darter, the team’s plan included noise monitoring, bubble curtain for in-water noise abatement during pile-driving and use of large diesel impact hammers.
Crews had a limited time frame to drive precast piles to avoid a migratory fish window, during which time a moratorium was imposed on pile-driving for several months. Due to highly variable soil conditions, the design-build team utilized a thorough test pile program to establish pile lengths. A test pile was installed at every pier. An average of four restrikes, at varying depths, were performed on every test pile. Crews pushed through four months’ worth of pile-driving in a few weeks, going seven days a week for 14 to 15 hours per day.
The project included construction of a 400-ft fishing pier, boat ramps and docks as well as relocating a local park and making deep ground improvements to the causeway surrounding the bridge. The scope of work also included fender system replacement and associated road work.
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