The new State Route 99 tunnel in Seattle is another step closer to opening as crews began testing the new ventilation systems Friday.
Giant exhaust fans in the tunnel will act like vacuum cleaners and pull smoke through vents in the tunnel walls if there is a car fire, the Washington Department of Transportation said. The smoke will be drawn through the ventilation corridor on the other side of the tunnel wall and out through the stacks of the operations building.
Crews also tested jet fans that push fresh air through the tunnel. The ventilation system is just one of the many safety systems WSDOT will need to check before the tunnel opens to the public.
Earlier this month, crews began moving Alaskan Way traffic west from under the viaduct in preparation for the tunnel’s opening. Contractors were wiring intersection for traffic signals, re-striping the roadway, and installing new signage.
Traffic on Alaskan Way will move to the new lanes by early fall, before the approximate three-week closure of the viaduct, which will precede the opening of the tunnel.