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SR 520 pontoons to float out in Aberdeen July 30-31

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Date:  Thursday, July 26, 2012

Contact: Jeff Switzer, SR 520 Communications, 206-770-3547

Watch our Tacoma pontoon time-lapse and see our simulation to show what’s planned in Aberdeen.

ABERDEEN – Six massive concrete pontoons – some of the largest ever built in Washington – will float out from Aberdeen next week, a major step toward assembling a replacement State Route 520 floating bridge later this summer.

Transportation Secretary Paula Hammond toured the Aberdeen casting basin today, July 26, as construction crews prepare to fill the basin with water and tow pontoons into Grays Harbor on the high tides Monday night, July 30, and Tuesday morning, July 31.

“Completing these pontoons brings us closer to replacing the aging and vulnerable floating bridge – a top safety and mobility priority for us and the region,” Hammond said. “This project will also continue to provide jobs in the Grays Harbor community as many more pontoons are built during the next two years.”

The new SR 520 floating bridge requires 77 pontoons in all: 33 to be built in Aberdeen and 44 in Tacoma. So far, crews in Aberdeen have built three longitudinal pontoons, one cross pontoon and two smaller supplemental pontoons. The longitudinal pontoons are the largest, weighing 11,000 tons apiece and measuring 360 feet long, 75 feet wide and 29 feet tall – as wide as they can be and still fit through the Hiram M. Chittenden Locks.

In May, cracks developed in an isolated area of a longitudinal pontoon. Additional cracks developed in a different pontoon in June. Repairs made since then were reviewed and endorsed by a panel of construction experts.

“We’re ready to float out these pontoons,” said Julie Meredith, SR 520 program director for the Washington State Department of Transportation. “We’re looking forward to connecting them starting this summer, and people crossing Lake Washington will have a front-row seat as the bridge takes shape.”

At the peak of construction on the first Aberdeen pontoons, nearly 400 workers were building forms, installing steel rebar and pouring concrete. There are five more cycles with 27 more floating bridge pontoons planned for construction in Aberdeen between now and 2014.

“Once the first six pontoons are floated out, we’ll shift gears for another round of construction – and we’ll again be turning to local carpenters, steel workers and concrete workers to help fill this basin with the next six pontoons,” said Phil Wallace, Kiewit-General project director for the pontoon project.

Completed pontoons will be inspected to make sure they are watertight. This summer, they will be towed around the Olympic Peninsula to Lake Washington and the next phase of construction.

The SR 520 Pontoon Construction Project created a casting basin to build 33 pontoons for a replacement SR 520 floating bridge on Lake Washington. Under a $367.3 million contract with WSDOT, Kiewit-General built the basin and is constructing pontoons. Construction began in spring 2011.

Kiewit-General-Manson Joint Venture has a $586.6 million contract with WSDOT to build the floating bridge project – including 44 pontoons in Tacoma and assembly of the floating bridge on Lake Washington. Construction began spring 2012.

The replacement six-lane floating bridge is scheduled to open to traffic by July 2015, but could open as early as December 2014 under the contractor’s aggressive schedule. Project information is available at

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