VDOT bridge construction earns national recognition

News VDOT May 05, 2003
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The Virginia Department of Transportation (VDOT) engineers have come up with innovations to build stronger and longer-lasting b

The Virginia Department of Transportation (VDOT) engineers have come up with innovations to build stronger and longer-lasting bridges, resulting in a $1 million funding award by the Federal Highway Administration (FHWA).

VDOT submitted proposals for innovative construction on three bridges. Those proposals competed with others from across the nation in the FHWA's Innovative Bridge Research and Construction Program.

The FHWA competition is open to state transportation departments that are conducting trials of new technologies, products and materials. In this year's competition, 57 projects were funded across the nation. Virginia was the only entrant to have as many as three proposals chosen and will receive a larger amount of funding than any other state. The proposals were produced by a collaboration of VDOT's Structure and Bridge Division, VDOT's Transportation Research Council at the University of Virginia, and Virginia Tech's Center for Bridge Engineering.

Bridges in Virginia's proposals are in Covington where Hawthorne Street crosses over the C&O rail line; on Rte. 58 in Lee County where the highway crosses over the Rte. 58 bypass; and on the Rte. 33 bridge over the Mattaponi River between King William County and King and Queen County.

The Hawthorne Street bridge, an aging truss structure, will receive a new deck made of fiber-reinforced polymer. Polymer will provide a much lighter deck than the solid concrete one now in place, and this should result in the load limit, now posted at five tons, being raised to 20 tons.

The Rte. 58 bridge will experiment with a technology incorporating fiber-reinforced ultra high-strength concrete. While normal concrete beams are expected to carry loads of 5,000 lb per square inch (psi), this type of concrete beam is expected to carry up to 30,000 psi. The technology increases the length of spans that can be built on bridges and decreases the number of piers that are necessary to support them.

The Rte. 33 bridge construction will employ high-performance, lightweight concrete beams with haunched sections. The beams' advantage will be their strength and length. While normal concrete beams can be designed for lengths up to 150 ft, the ones to be used here will be designed up to 240 ft. The extra length makes these beams competitive with steel beams of long lengths.

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