A second set of new pontoons for the SR 520 bridge left the Aberdeen casting basin overnight Sunday into Monday morning, according to the Washington State Department of Transportation. The late-night float-out was set to take advantage of high tide.
In the second cycle, crews built three longitudinal pontoons, two supplemental stability pontoons and one cross pontoon. The 360-foot-long longitudinal pontoons are the backbone of the new SR 520 floating bridge being built on Lake Washington; the supplemental pontoons provide stability and flotation, and the cross pontoons cap the bridge on the east and west ends. Crews will build a total of six cycles of new pontoons in Aberdeen, and are expected to complete the pontoons in 2014.