A Tampa, Fla., contractor cut the time and cost of building a low-profile bridge by using a custom flying deck-forming system that remained rigid under extreme loads and long spans. The 650-foot-long, 90-foot-wide bridge—located on Blind Pass Road (State Road 699) in St. Pete Beach, Fla.—has an 18-inch-thick solid-concrete deck with 40-foot-long spans and no supporting girders. The deck-form panels were designed to support a full bridge span without intermediate supports, eliminating the need for midspan crutch bents.
The four-lane bridge, which crosses an intracoastal waterway, was designed to have a maximum clearance over the water of only 17 feet. Because of the low clearance, however, the contractor needed a deck-forming system that would be deep enough to support the heavy loads yet not so deep that, when installed at the shorelines, the forms would be immersed or require excavation for placement. The custom deck forming system that met those requirements consisted of three stiffened steel plate girders, intergirder bracing, roll-out carrier beams and aluminum beams with plywood decking. The system was able to support the weight of the concrete and reinforcing steel for a 40-foot span (approximately 550,000 pounds) with a midspan deflection of only 5/8 inch. The forms also could be flown and set by crane, which simplified relocation.