Bridge - Award of Merit

Atlantic Intracoastal Waterway Bridge
Great Bridge, Va.

The new Atlantic Intracoastal Waterway Bridge at Great Bridge, Va., is the latest in a series of structures that dates back to a 40-yd. span across what was once the southern branch of the Elizabeth River in the 1770s.

Even with the advantages of 21st Century engineering techniques, however, the 300- ft.-long five-lane, hydraulically driven, double-leaf bascule bridge represents a design and construction effort truly befitting of its namesake community.

Consider the constraints. Erecting a replacement to the existing two-lane double-span swing bridge could not disrupt the flow of either vessels or vehicles. The U.S. Coast Guard allowed only four 72-hour channel closures during the 800-day construction period, each of which had to be scheduled to the precise hour 90 days in advance.

Landside construction would take place within the confines of a busy commercial area. And because the site had also been the setting of significant American Revolution and Civil War battles, the project team had to continually watch for potentially significant artifacts.

Overcoming these and other obstacles made teamwork essential among the project's co-owners, engineer and contractor. For example, the bridge's original design called for the bridge leaves to be operated by 1,500-ton hydraulic overhead counterweights to provide a low-level profile and avoid the need for deep cofferdams.

To expedite construction, the engineer, URS Corp., of Virginia Beach, Va., and the contractor Tidewater Skanska Inc. of Norfolk, Va., elected to make several design adjustments to split the structural connections and erect the counterweights shored in the closed position.

The 270-ton, 140-ft. leaf portions were preassembled offsite and floated into place during two of the channel closings. Roadway decks and the final sections of counterweights were built during two approved channel closures.

Maintaining a pinpoint schedule was not the only ongoing challenge. Beneath the cofferdams lay soil and groundwater with higher-than-expected concentrations of lead and hydrocarbons. An innovative dewatering system diverted and separated incoming channel water from the contaminated groundwater, thereby reducing the amount of water requiring treatment.

The project team's commitment to collaboration paid off in both precision and productivity. Each of the four 42-ton track girders was set to .03-in. tolerance for horizontal and vertical alignment, with a level tolerance of .006 in. per foot. When the leaves were closed and mated for the first time, they were within 1/8 in. of the 110-ft. plan length, and leaf alignment was within .5 in. of specification.

"The success of this project is a credit to all the team members," the judges said. "That fact that they were able to keep two lanes of traffic open was amazing. And they did it three months ahead of schedule with no lost-time injuries."

Along with giving Virginia its first fully hydraulic bridge, the project also revealed a long-hidden part of its past. During excavation work for the bridge approaches, the project team uncovered portions of an old cypress timber roadway laid by the British Army in 1776. The relics were turned over to the local historical society, which plans to build a museum adjacent to the area's newest "great" bridge.

Owner: U.S. Army Corps of Engineers
Co-Owner: City of Chesapeake
Design Engineer: URS Corporation
Prime Contractor: "Tidewater Skanska, Inc."
Hydraulic Equipment: Supply Bosch Rexroth
Structural Steel Fabricator: PDM Bridge
Hydraulic Fluid Power Systems Installation/Bridge Controls: Electro Hydraulic Machinery Co.
Soil Anchors: Foundation Services/Hayward Baker
Electical and Controls: "J.C. Driskill, Inc."
HVAC/Mechanical: Smith & Keene
Sitework: "Womack Contractors, Inc."

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