BRIDGE CONSTRUCTION: 4th cycle of pontoons on their way to S.R. 520 floating bridge

WSDOT now two-thirds completed with pontoon construction

Bridge Construction News WSDOT April 16, 2014
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Another six S.R. 520 bridge pontoons began floating out of the Aberdeen, Wash., casting basin late last night, marking completion of the fourth of six cycles of pontoons being built in Grays Harbor.


“With the fourth cycle complete, we’ve reached another important milestone for a new S.R. 520 floating bridge,” said Julie Meredith, S.R. 520 program director for the Washington State Department of Transportation (WSDOT). “We’re now two-thirds of the way done with all pontoon construction. In the coming months, the public will start to see the new floating bridge take shape as we begin to align, join and anchor the pontoons together on Lake Washington.”


The fourth cycle of pontoon construction included four longitudinal pontoons and two supplemental stability pontoons. The 360-ft-long longitudinal pontoons will form the backbone of the new bridge, while the smaller, supplemental pontoons provide additional stability and flotation.


Crews lifted three 50-ton gate sections last night to clear the way for the pontoons to float into Grays Harbor. The first pontoon exited the casting basin around 10:30 p.m., with the final pontoon expected out around 3 a.m. today.


The new pontoons will be inspected at the port of Grays Harbor and will then be temporarily moored. They will later be towed to Lake Washington for construction of the new S.R. 520 floating bridge. Full pontoon tracking details are posted online.


The new floating bridge is scheduled to be open to traffic in April 2016. More information about the S.R. 520 Bridge Replacement and HOV Program can be found at

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