Anchoring spuds for a 520 floating bridge barge lost traction during Sunday night's windstorm, an investigation showed.
That resulted in the barge and the crane it was carrying to break away from the bridge and float toward the Laurelhurst neighborhood, eventually stopping feet from a residential dock in shallow water.
The spuds are vertical posts that secure the barges to the bottom of Lake Washington. On this particular barge, the spuds were in an area of the lake bed that slopes downward, creating a steep transition. Because of the slope, there is less muddy debris and more till, suggesting there was not enough soft material to secure the spuds as winds reached gusts of 30-40 mph Sunday night.
Staff for Mowat-American, the 520 West Connection Bridge project contractor, said they're taking extra precautions to ensure this doesn't happen again. The barge was brought back to the jobsite by a tugboat and is now anchored in flatter, shallower water; creating a more secure environment for the spuds.
WSDOT and Mowat-American determined the new and existing 520 floating bridges were unaffected and the loose barge and crane did not cause any additional damage.
The new bridge, which is currently under construction, is designed to withstand winds of up to 89 mph. For now, if sustained wind gusts reach 50 mph for more than 15 minutes, the 520 floating bridge is closed to traffic and WSDOT crews open the drawspan.