Socastee Swing Bridge: Asset Management Contract
Bringing an innovative approach to a unique, complicated problem makes for a successful solution in the present — and a better future. Serving as a popular route to school for students, as well as commuters, the Socastee Swing Bridge is a 217-foot truss swing span. It crosses the Intracoastal Waterway, which falls within the jurisdiction of the U.S. Coast Guard (USCG). The bridge operates "on demand" of the boat captains approaching it and clears only about 10 feet over the surface of the water at low tide, making it low enough to require frequent openings. Consequently, this in-demand bridge must work at optimal efficiency to avoid delays.
During routine operations as part of our bridge asset management contract with the South Carolina Department of Transportation (SCDOT), we identified a failed bearing in the gearbox that was causing further damage each time the bridge operated. Complicating efforts to assess the problem, there were less than six inches of space between the gearbox and the concrete deck.
After reviewing the problem with SCDOT and considering all of the traffic issues, we consulted with the USCG to create a plan that would preserve the gearbox during operation of the bridge as well as minimize impacts on land and marine traffic during repairs. We implemented a temporary pneumatic tugger/winch system to open and close the bridge without use of the gearbox to prevent more damage.
Because of the unique configuration of the bridge and the limited workspace, we cut a 5 feet by 8 feet hole in the deck of the bridge to access the gearbox and create a permanent access hatch for future inspections. But that wasn't the only issue that required a specific approach. Weighing 8,000 pounds and located only 15 feet below the operator's platform, the gearbox could not be removed for repairs with a conventional crane. A 50-ton, rotator tow truck solved our problem. The gearbox was safely removed and repaired before we reinstalled it — just in time, too.
By August 16, this well-traveled bridge in the Socastee Historic District had returned to full service and normal traffic conditions resumed in time for local schools opening two days later.
"Movable bridges are complex machines that carry traffic, not simply bridges that move," says Robert Moses at HDR. "The right asset management partner can readily navigate the unique challenges and extend the life of these critical assets."