Motorists traveling through the Seattle area can expect road and lane closures this weekend as crews conduct maintenance and repairs.

The Highway 99 tunnel’s northbound lanes will be closed for regular monthly maintenance from 10 p.m. Friday until 8 a.m. Saturday.

Crews will check jet fans, the fire-detection system, traffic cameras and overhead signs as well as clean the tunnel. In August, crews will close the southbound lanes for similar work.

On Saturday, from 6 to 11 a.m., one lane in each direction will be closed on the Montlake Bridge while crews perform maintenance work.

Further east, Highway 18 between Issaquah-Hobart Road Southeast and Interstate 90 will be closed from 9 p.m. Friday to 1 p.m. Sunday as crews repair guardrails and repave portions of the roadway near Tiger Mountain. Signed detours will direct travelers how to get around.

WSDOT suggests commuters use routes like Interstate 405 and I-90 as well as highways 167 and 900 as alternatives.

Updated traffic information is available through WSDOT’s traffic app and on its Twitter feed.