As of tonight, six bridge pontoons will be floating toward Seattle, the first batch to leave Aberdeen, Wash., as part of the State Route 520 floating bridge replacement project.
Crews have filled the casting basin at the construction facility in the port city of Aberdeen, southwest of Seattle, with water, preparing for tonight’s high tide, when the pontoons—including the largest ever built in the state—will start riding the waves around the Olympic Peninsula en route to their final destination connecting Seattle with points east in a complete reconstruction of what is already the world’s longest floating bridge. The new six-lane bridge is on schedule for a December 2014 opening.
The new span features 77 pontoons, with 33 getting constructed in Aberdeen and 44 more in Tacoma. Already, three longitudinal pontoons, weighing 11,000 tons each and measuring 360 feet long, 75 feet wide and 29 feet tall—the widest possible size that can fit through the Hiram M. Chittenden Locks in Ballard, the transition point from the Puget Sound to the waterways that will lead to the bridge’s final destination floating on Lake Washington—one cross pontoon and two smaller supplemental pontoons make up the first batch headed for Lake Washington flotation.
The process starts at approximately 8 p.m. Pacific this evening and stretches toward midnight.
As part of a SR 520 Pontoon Construction Project awarded to Kiewit-General under a $367.3 million contract, nearly 400 workers were building forms, installing steel rebar and pouring concrete at the peak of construction.
There are five more construction cycles with 27 more floating bridge pontoons planned for creation in Aberdeen between now and 2014. Tacoma’s facility will hand the smaller batches of pontoons.
The float-out of the original six was delayed after inspections in May showed cracks in the concrete on an “isolated area of a longitudinal pontoon.” Additional cracks developed in a different pontoon in June. After repairs were made to those pontoons, the structures were deemed watertight and changes were made to the process of constructing the pontoons.
As the pontoons start arriving at the lake near the University of Washington and in a highly populated area, Kiewit-General-Manson Joint Venture (the group with a $586.6 million contract to build the floating bridge and construct the Tacoma-based pontoons) crews will connect them, allowing travelers along the current bridge an ongoing view of the new SR 520 during construction.
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