People who use Highway 99 through Seattle should plan to use an alternate route Thursday night and early Friday morning.
The highway tunnel closure will allow time for regular maintenance including tests of the roadway fire suppression system along with inspections of traffic cameras and fire extinguishers. This ensures the tunnel is running smoothly and warranties are being maintained. Both directions of the tunnel will close from 9 p.m. Thursday, June 18 until 4 a.m. Friday, June 19.
Just north of the tunnel, the northbound Highway 99 Aurora Bridge will be reduced to a single lane as crews replace an expansion joint, the last stage of the Aurora Bridge painting project. This work protects the bridge from corrosion while preserving its structural integrity. Work will last from 9 p.m. Thursday, June 18 until 5 a.m. Friday, June 19.
Drivers are encouraged to use alternate routes like I-5 Thursday night and early Friday morning.