SEATTLE — Wind and rain pounded the 520 floating bridge on Saturday forcing State Patrol to shut it down. Fifty drivers abandoned their cars on the bridge. The new 520 bridge is under construction, so KIRO 7 went to Department of Transportation engineers to find out how the chaos will be avoided.
The biggest change to avoid shutting down the bridge is the height. Currently drivers are 8 to 10 feet above the water level. And in big wind storms like Seattle saw over the weekend, waves can crash over the bridge. The new bridge will have an elevated roadway.
"The new structure is roughly 20 feet off the lake so you won't have that wave action in the future," said WSDOT engineer Dave Becher.
It's important to note that it was State Patrol who shut down the 520 bridge, not WSDOT. They had engineers on-site Saturday as they do any time they have winds over 40 mph, but Becher said there were not sustained gusts of 50 mph. That is the threshold for WSDOT to shut down the bridge to protect the draw span.
The new 520 floating bridge won't have a drawspan.
"We've increased the height of the east high rise," said Becher. "Which will allow vessels to get under the bridge so we won't need a drawspan."
The new bridge will be able to resist windstorms up to 89 mph. And the elevated road will allow maintenance crews to work under the bridge and avoid all those weekend and night closures.
The new 520 floating bridge is scheduled to open to traffic in late 2015 or early 2016.
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