SNOQUALMIE PASS, Wash. — Westbound drivers experienced delays of up to an hour on Interstate 90 going over Snoqualmie Pass after unscheduled maintenance repair crews blocked traffic Sunday.

The delays began about 1 p.m., and due to high volume of traffic on the highway, state Department of Transportation officials expected the lengthy backup to last well into the evening.

Online maps of the traffic showed slowdowns from about milepost 85 to milepost 78, near Cle Elum, and again just after Easton near milepost 70 until milepost 58, by the snowshed. All lanes are open now, but traffic will probably remain heavy until Sunday night, a DOT news release said.

Eastbound lanes were not affected.

Drivers can check the state DOT website for frequent traffic updates.