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Because each 70-foot beam weighed 5,000 pounds, fewer delivery trucks were necessary, contractors didn't need a 200-ton crane, and they accessed the job site from the existing bridge without violating load restrictions. The world's largest hybrid-composite bridge opened to traffic on June 11. Photo: HC Bridge Co. LLC

The American Association of State Highway and Transportation Officials is promoting rigidified fiber-reinforced polymer (RFRPAB) tube arches and hybrid composite beams (HCB) — both developed with the Maine DOT — as options for designing and building lighter and longer-lasting bridges.

Maine just replaced a wooden bridge with beams made of fiber-reinforced polymer instead of precast box beams as planned. The project was made possible by a 2008 state law that included a Composite Initiative and allocated $11 million for roads and bridges.

Construction began with the installation of seven pile bents comprised of concrete-filled pipe piles with rock anchors tensioned into bedrock. All but one bent comprised one row of piles to allow for deflection under temperature loads; one was made with two rows to provide longitudinal fixity. Expansion joints are located at the abutments.

Developed by HC Bridge Co. LLC and manufactured by Harbor Technologies LLC, both also of Maine, the hollow composite beams were driven onto the existing bridge and off-loaded using the same barge and crane needed for the substructure. After the first four spans were set, the beams were filled with concrete for compression reinforcement. Then the contractor began placing reinforcing for the deck pour. With top flange widths of 4 feet the beams were placed tip to tip, so deck forming wasn't required.

Scupper details, screed rails, and reinforcing details were the same as those for a precast concrete bridge.