Pontoon testing complete for 520 replacement project | Transportation

The construction of the test pontoon for the State Route 520 Bridge replacement is complete and considered to be a “complete success.”
 
While other aspects of replacing the SR 520 Bridge, which spans Lake Washington connecting Seattle and Bellevue, may have been more controversial, as far as the engineering science goes, the progress and advancements have been greater than expected.
 
WSDOT has determined that the 33 pontoons – the biggest ever built in the state, each of them 75 feet wide by 360 feet long by 28.5 feet high – will be manufactured in Grays Harbor County.

Upon final environmental review, a pontoon casting facility will be built at either the “preferred” site of the former Weyerhaeuser log sorting yard in Aberdeen or the 90-acre alternative site in Hoquiam owned by the Anderson-Middleton Company.

The test pontoon constructed at Satsop Development Park is 120 feet long, 38 feet wide and 28.5 feet tall, roughly one-sixth the size of the largest of the final pontoons WSDOT will build in Grays Harbor for the new SR 520 floating bridge.

Photo courtesy WSDOT