Steel in the News
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Posted by Tasha Weiss on January 21, 2013 at 10:51 AM.
A 335-ft-long, 85-ft-wide lift span was floated in and connected to two tower structures last week for the new Gilmerton Bridge in Chesapeake, Va. The new steel lift bridge provides an improved vertical clearance of 35 ft and will see 40% fewer openings each year, easing traffic and marine congestion alike. (Click on the image to see a photo of the completed bridge lift.) Photo: Courtesy of Modjeski and Masters
The $134 million Gilmerton Bridge Replacement project on Military Highway in Chesapeake, Va., provides a new steel lift bridge over the southern branch of the Elizabeth River, replacing the existing double-leaf bascule bridge constructed in 1938. The Virginia Department of Transportation (VDOT) recognized the need to replace the aging bridge to accommodate future growth in an area becoming increasingly congested, and to facilitate better flow of marine traffic.
The replacement project requires the new bridge to be built on the exact same alignment as the existing bridge. Bridge engineering firm Modjeski and Masters designed the new 335-ft-long, 85-ft-wide lift span. Due to the exceptional width, four 15-ft diameter sheaves were needed on each tower structure. Eight 12-ft-diameter drilled shafts were designed to reach 120 ft below ground and are some of the largest ever constructed using the oscillating method. With only 25 ft between the Gilmerton Bridge and an adjacent railroad bridge, seismic instruments were used to monitor potential settlement of the railroad bridge foundations during installation of the new drilled shafts.
Last week the lift span was floated in and connected to two tower structures, and the existing bridge reopened to traffic one week earlier than projected. Mariners will also benefit from the new bridge span due to its enhanced vertical clearance from 11 ft to 35 ft in the closed position and up to 135 ft when the lift span is opened.
Additional work to the Gilmerton Bridge Replacement Project will include the demolition of the existing bridge and construction of the northside approaches, with completion scheduled for early 2014. When the new bridge is complete, it will be 1,908 ft long and 85 ft wide which will increase traffic lanes on Military Highway from four lanes to six.