SR 99 tunnel in Seattle reopened after power outage

The SR 99 tunnel in Seattle has reopened in both directions Thursday morning after a power outage.

The Washington Department of Transportation (WSDOT) is asking drivers and commuters to seek alternate routes.

Heads up: Due to a power outage, the SR 99 tunnel in Seattle is CLOSED in both directions.

Seek alternate routes.@SEACityLight @seattledot pic.twitter.com/hJogeo2647

— WSDOT Traffic (@wsdot_traffic) November 20, 2025

Both directions were closed from 7 a.m. until just before 11 a.m., when the southbound lanes were able to open up. The northbound lanes reopened shortly after.

The tunnel was shut down after the power outage due to the fire suppression and ventilation systems being offline. As for why there is no backup power system in place, RB McKeon, communications manager for WSDOT, said there is redundancy in the system.

“We would normally receive power from the north end. That switch gear has failed, and although our emergency generators have kicked on, they are not designed to run the ventilation and some of the other systems,” McKeon told KIRO Newsradio. “This has resulted in the closure of the tunnel. We are in touch with Seattle City Light and they are working to get power restored and we are also in touch with the manufacturer of our switch gear and have asked them for an assessment and recommendations.”

Due to the power outage, Sounder trains were also immobilized.

According to Seattle City Light, 172 customers were affected by the power outage.

This is a developing story, check back for updates 

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