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Friday, March 09, 2012
Jamie Holter, WSDOT Communications, 206-719-7535 (cell)
SEATTLE – Emergency underwater repairs will continue Saturday, March 10, as divers replace a second damaged State Route 520 floating bridge cable connection found on Friday.
As part of routine bridge inspections, Washington State Department of Transportation bridge engineers on Thursday discovered a damaged hardware connection on the west end of the floating bridge where one of 58 anchors ties to the bed of Lake Washington. Working in water 30 feet deep, divers repaired that connection by Friday afternoon.
As a precaution, bridge engineers called for inspections of three other similar anchors and found the same problem on one additional connection at the far east end of the bridge. Two other locations were inspected and did not have the same damage.
“Once the first repair was made we shifted our contractor to make similar repairs at the second location,” WSDOT Assistant Regional Administrator Dave McCormick said. “It’s essential to make these repairs promptly.”
On Friday afternoon, divers set up equipment near the east end of the floating bridge, where they will work in water 60 feet deep starting again Saturday morning.
The bridge remains open and safe to drive, but coincidentally will close for prescheduled weekend construction at 11 p.m. today. Construction crews will demolish an overpass in Medina and dig huge trenches across highway lanes in several locations on the Eastside throughout the weekend.
One-third of the floating bridge anchor cables are inspected every two years, and 15 of the 58 were replaced in 2010. Initially corrosion was suspected as a cause of the damaged anchor connections. While a final determination is pending, bridge engineers say it appears that the steel pin hardware connections were bent by forces produced by wind and wave action on the lake.
A media update regarding the emergency repair work and weekend Eastside demolition is planned at noon Saturday, March 10, at the Evergreen Point Road overpass in Medina.
Repair work is preliminarily estimated to cost up to $60,000 and is expected to be completed as soon as Saturday.
Immediate repairs were necessary because engineers said connecting pins tying together anchor cables and anchors already had slid out of position. If a pin was forced completely out of position, separating the bridge and cable from the anchor on the lakebed, it would reduce the bridge’s ability to withstand large storms.
SR 520 construction closure reminder
Eastside demolition work begins 11 p.m. Friday, closing the floating bridge and highway until 5 a.m. Monday, March 12.
Closure details at a glance
- Mainline SR 520 and all connected ramps between Montlake Boulevard in Seattle and I-405 in Bellevue will be closed from 11 p.m. Friday, March 9, to 5 a.m. Monday, March 12.
- The 108th Avenue Northeast on-ramp to eastbound SR 520 will remain open to traffic.
- Two sections of SR 520 will remain open to traffic: I-5 to Montlake Boulevard and areas east of I-405.
Closure information and detour maps are online. Night work is planned, and residents near the work zone are likely to hear construction noise. Weekend closure details are available at www.wsdot.wa.gov/Projects/SR520Bridge/WeekendClosures.
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