As baseball fans cheer the start of a new season, the Washington State Department of Transportation is celebrating a major milestone for the new State Route 520 floating bridge. The final three pontoons built for the bridge are in the process of leaving Grays Harbor today and should arrive in Seattle as soon as Thursday, April 9, 2015.

The football-field-size structures will then move through the Hiram M. Chittenden Locks in Ballard on their way to Lake Washington. There, they’ll join the 74 previously constructed pontoons that together will support the world’s longest floating bridge. The Locks are a popular location to see the pontoons, as are other viewpoints in the Seattle area.

A pontoon photo contest on Twitter is now underway, offering creative shutterbugs the chance to win a tour of the new floating bridge as it’s built on Lake Washington. Five winners will be selected for the best pontoon photos, as judged by Jon Marmor, editor of the University of Washington’s Columns Magazine. Past photos of SR 520 pontoons will be accepted, as will new photos. Submissions will be accepted through 12 p.m. Monday, April 13, 2015.

“This contest is a fun way to acknowledge the four years of hard work that went into building the 77 bridge pontoons,” said Dave Becher, WSDOT engineering manager with the SR 520 Floating Bridge and Landings Project. “The new bridge will serve as a vital connection for communities on both sides of the lake for decades to come, and this photo contest will help us commemorate this great milestone.”

WSDOT contractors built pontoons for the new SR 520 floating bridge in Aberdeen and Tacoma. Of the 33 constructed in Grays Harbor County, 21, including the final three, are the massive longitudinal pontoons – 360 feet long, three stories high, and 11,000 tons. They form the backbone of the new bridge.

Contractor crews on the lake continue to bolt together and anchor pontoons in their final position. The new bridge, with six lanes, a shoulder for disabled vehicles, and a bicycle/pedestrian path, is designed to resist stronger windstorms than the current bridge. The new bridge is scheduled to open in spring 2016.

For information on road closures associated with SR 520 construction, visit the SR 520 Orange Page and follow us on Twitter.