Local Information

Seattle's Highway 99 timber bridge replacement starts now

Friday, February 22, 2013 - 08:32

Broch Bender, WSDOT communications, 206-440-4699 (Shoreline)

SEATTLE – Most people who cross this bridge every day are unaware of what lurks beneath – a prism of yellow-tagged, weathered and splitting wooden crossbeams and 60-year-old timber piles, sprawling 450 feet long over railroad tracks.

Contractor crews for the Washington State Department of Transportation this week brought in the heavy equipment to bring down and replace an elevated section of State Route 99 just south of the West Seattle Bridge. When they finish, they’ll leave Seattle’s SODO neighborhood with a stronger concrete bridge better equipped to withstand the test of time.

“If you’ve ever been underneath and heard the rattling of the wooden slats or seen the rotted-out cross beams, you would know why we are replacing it,” said Rick Rodda, WSDOT bridge engineer.

The bridge carries four lanes separated by concrete barrier. This weekend, Feb. 23-25, crews will close all lanes on SR 99 to shift traffic to the west side of the overpass. Work to demolish and rebuild the east side begins Feb. 25.
“This bridge was built as a temporary structure back in 1956,”Rodda said. “That’s a long time as a temp. I think it’s earned permanent status.”
The bridge has been moving steadily up the replacement list for 15 years.
Crews will demolish and rebuild one side of the bridge at a time to keep traffic moving at reduced speed in both directions until the work is complete. Traffic will get through the work zone in one southbound lane and two northbound lanes. Occasional weekend closures of all lanes will be necessary.

“An estimated 45,000 commuters, travelers and trucks carrying freight to and from the Port of Seattle use the route every day,” said Hien Trinh, WSDOT project engineer. “It’s not as highly used as I-5 but it’s if it breaks down, the whole region feels it.”

The $9.2 million construction project is scheduled to be complete in June 2014.

Construction summary

  • The work zone is SR 99 between S. Nevada Street and an area just south of the West Seattle Bridge.
  • Crews will close SR 99 at 4:30 a.m. Saturday, Feb. 23 to shift traffic and restripe lanes.
  • When the road opens at 5 a.m., Monday, Feb. 25, traffic will be on the west half of the bridge and a speed limit of 40 mph will be in effect.
  • Traffic modeling shows southbound traffic will be the most affected between 6 a.m. and 8 a.m. and 2 p.m. and 5 p.m., but the existing capacity can handle the commute without significant backups.

Construction progress tools, including traffic and detour maps are available here, or go to http://www.wsdot.wa.gov/ and search “SR 99 timber bridge.”


WSDOT keeps people, businesses and the economy moving by operating and improving the state's transportation systems. To learn more about what we're doing, go to www.wsdot.wa.gov/news/ for pictures, videos, news and blogs. Real time traffic information is available at www.wsdot.wa.gov/traffic or by dialing 511.

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