An enormous boulder crashed onto State Route 155 south of Steamboat Rock State Park overnight on Friday. (WSDOT)
STEAMBOAT ROCK, Wash. — An enormous boulder crashed onto State Route 155 south of Steamboat Rock State Park, leaving a crater in the roadway and forcing crews to plan controlled blasting before they can clear the landslide and repair the highway.
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The slide occurred overnight and sent large rocks onto the roadway. The Washington State Department of Transportation closed one lane as crews assessed the damage.
WSDOT reported no injuries.
Last night a rockslide closed a lane of SR 155 south of Steamboat Rock State Park. One of the rocks is large enough it will require blasting to break it up before it's cleared. Plan for auto-flagger controlled traffic and delays until clean up and repairs are complete. @wspd6piopic.twitter.com/wfQHbn9kA5
WSDOT crews determined that one of the fallen rocks is too large to remove with standard equipment. Workers will use controlled blasting to break the rock apart before clearing debris from the roadway.
Crews are managing traffic with alternating one-lane, auto-flagger-controlled operations. Drivers should expect delays until cleanup and repairs are complete.
WSDOT has not released a timeline for reopening all lanes. Officials said crews must stabilize the slope before completing repairs.
Storms trigger landslides across the state
The SR 155 slide follows a wave of landslides triggered by December’s atmospheric river storms.
Heavy rain and saturated soils caused debris flows, rockfalls, and washouts on multiple highways statewide. Several major routes saw closures or long-term restrictions.
U.S. Route 2 over Stevens Pass closed for extended periods after repeated debris slides and flooding. Emergency repairs remain ongoing.
State Route 20 west of Winthrop closed for several days after mudslides damaged the roadway.
Interstate 90 near North Bend closed briefly when debris slid onto travel lanes.
WSDOT does not publish an annual count of highway closures caused specifically by landslides. However, the Washington Geological Survey estimates that hundreds to thousands of landslides occur statewide each year. Many happen during prolonged rain events.
Landslides remain a national safety concern
Landslides pose risks well beyond Washington.
The U.S. Geological Survey estimates that landslides cause an average of 25 to 50 deaths each year in the United States. They also cause billions of dollars in property and infrastructure damage annually.
Transportation corridors in mountainous and river-adjacent areas face the highest risk.
As work continues on SR 155, WSDOT urges drivers to slow down in slide-prone areas and follow traffic control devices. Officials also recommend checking travel alerts before driving during storms.
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