About five feet of rock and dirt partially covered the railroad tracks just south of Mukilteo.
The debris was removed by midday, but BNSF Railway suspended passenger service for 48 hours as a precaution, spokesman Gus Melonas said.
Service is scheduled to resume by 10:40 a.m. Thursday.
Mudslides have been commmon in the area, with three mudslides interrupting passenger train service since Thanksgiving.
Freight service resumed after the slide was cleared, Melonas said.
To help passengers, Sound Transit added special bus service Tuesday.
For this morning's commute to Seattle, passengers can pick up the ST Express Route 510 at the Everett Station, which departs every 10 minutes.
Riders also can take Community Transit Route 417 from the Mukilteo ferry terminal that departs at 5:49 a.m., 6:21 a.m., and 7:53 a.m.
Sounder rail service between King Street Station and Edmonds is not affected and has no changes on its schedule.
For more information or updates, go to www. soundtransit.org.
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