Local Information

More floating-bridge pontoons arriving on Lake Washington

Wednesday, March 12, 2014 - 18:07

Roger Thompson, SR 520 Communications, 206-819-7230

Additional pontoons slated for completion this spring in Aberdeen

SEATTLE – More pontoons for State Route 520’s new floating bridge are about to arrive in Lake Washington.

The first of two supplemental pontoons being towed this week from Tacoma to Lake Washington is scheduled to reach the Hiram M. Chittenden Locks late this afternoon or early evening, Wednesday, March 12. Tug boats then will guide the massive concrete box through the Lake Washington Ship Canal before reaching the lake’s western shore, likely in midevening. A second Tacoma-built supplemental pontoon is scheduled to arrive Thursday afternoon, March 13.

“We’re well past the halfway point with pontoon construction” said Julie Meredith, director of the Washington State Department of Transportation’s SR 520 Bridge Replacement and HOV Program. “We’re seeing strong progress in every phase of the highway program.”

The two pontoons arriving this week will be the 31st and 32nd pontoons towed to Lake Washington as part of construction of the new floating bridge. To date, 46 of the new bridge’s 77 pontoons have been constructed.

Six additional pontoons under construction in Aberdeen are scheduled to be completed this spring. Other already-built pontoons now moored in Aberdeen will be towed to Lake Washington later this spring.

Meredith noted that construction of the floating bridge’s 766 concrete deck panels began in February in Kenmore and that work on the Eastside Transit and HOV Project will wrap up later this summer, just as construction begins on a new, 1.1-mile-long bridge linking the new floating bridge with Seattle’s Montlake neighborhood. She also pointed out that the interim West Connection Bridge should be completed this fall, while the new floating bridge is scheduled to open in spring 2016.

You can find more online about the different types of SR 520 pontoons and track the status of their construction. You also can track tugboat Terilyn and view the general Puget Sound location of the pontoons on their trip from Tacoma to Seattle. A map of suggested viewing locations (pdf 2.4mb) along the ship canal also can be found online.

Additional information about the SR 520 Pontoon Construction Project also is available online.

About supplemental pontoons
Supplemental pontoons flank either side of the floating bridge to give the structure added stability and flotation. The supplemental pontoons are 98 feet long, 28 feet high and 50 to 60 feet wide. Their weight ranges between 2,650 and 3,000 tons. By comparison, the bridge’s longitudinal pontoons, which lie directly under the bridge deck, are 360 feet long, 75 feet wide, 28.5 feet tall, and weigh 11,000 tons.

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