Seattle's SR 99 tunnel to undergo first six-year inspection
(UI) — The State Route 99 tunnel in Seattle will undergo its first major inspection since opening in February 2019.
The Washington State Department of Transportation (WSDOT) will conduct a comprehensive six-year inspection, which is required due to the tunnel's unique structure and federal regulations.
The SR 99 tunnel, built to replace the aging Alaskan Way Viaduct, will have its electrical and mechanical systems examined in detail. This includes assessments of the tunnel’s fire detection system, communication systems, lighting, cameras, ventilation, and drainage systems. The inspection will also cover operational testing of key safety features such as jet fans and centrifuge fans.
WSDOT's Bridge Preservation team is bringing in specialized inspectors and vendors from out of state to complete the two-week inspection, which will ensure that the tunnel remains safe and fully operational for the years ahead.
The tunnel was chosen as the replacement for the Alaskan Way Viaduct after a 2001 earthquake damaged the structure, prompting years of studies and planning.
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