Both directions of the State Route 99 tunnel in Seattle will close for scheduled maintenance from 10 p.m. Friday, June 7, until 6 a.m. Saturday, June 8.

According to a news release, the tunnel closure will allow the Washington State Department of Transportation to conduct several important tasks, including:

• Fire extinguishers inspections.

• Lube and test run the jet fans.

• Inspect fire sprinkler heads.

• Check transformer oil.

• Camera repairs.

• Lighting repairs.

• Variable message sign repairs.

• Tunnel wall washing.

People traveling through the area Friday night should use alternate routes. Real-time travel information is available via the WSDOT mobile app and the real-time travel map.