HYAK, Wash. – The spot where a rock slab fell on Interstate 90 and crushed three 28-year-old women as they returned from a concert in Eastern Washington was considered low-risk by state transportation officials who weren’t planning any immediate safety measures to guard against such an accident.
Returning from The Gorge Amphitheatre in Grant County early Sunday, Janet J. Ichikawa of Lynnwood, Janel A. Lindsey of Bothell and Heather E. Rider of Castle Rock were on I-90 about two miles west of Snoqualmie Pass when a large boulder fell from the cliff and onto their Volvo.
In the aftermath of the tragedy, Transportation Department officials say the section hadn’t been considered dangerous enough to require immediate attention in recent years.
“We had really no warning here,” Tom Badger, the agency’s assistant chief engineering geologist, said Monday.
Monday evening a boulder the size of a large truck tumbled onto the roadway just feet from Sunday’s collapse. No one was injured but two of the three westbound lanes were closed until a geologist could examine the hillside to assess the danger and determine whether the slope could be stabilized.
In the 1990s, the department rated 2,500 unstable slopes along state highways under a program to possibly prevent potential landslides and rockslides. In its assessment, the department considered the likely magnitude of a slide, its impact on the highway, traffic volumes, slide and accident history, and annual maintenance costs.
Slopes were rated from lowest risk at 33 to the highest of 891. Sunday’s accident involved one with a 273 rating — below the required 350 rating necessary for the agency to address, said Steve Lowell, the department’s chief engineering geologist.
To fix problem spots the department removes loose rock, scales back slopes, inserts large bolts in rock faces to stabilize them, builds protective walls along highways and installs cable nets to keep boulders from crashing onto roads.
There are hundreds of proposed projects throughout the state with a total cost of nearly $100 million, however the agency has less than $13 million to improve unstable slopes.
The slope near Snoqualmie Pass is nearly vertical, created when road builders blasted a new route for I-90’s westbound lanes in the 1970s. During its earlier assessment, engineers estimated that falling rocks were likely to be less than 1 foot in diameter and total less than 3 cubic yards. Rocks were unlikely to reach the freeway’s travel lanes.
Lowell said the slope had been undisturbed since construction.
“We hadn’t had a history of significant failures in this area,” Badger said.
Investigators will examine why the slide occurred now. Initially they thought heavy rain Saturday might have loosened the rock, about 5 to 10 feet above the roadway.
A chunk of granite about 60 feet high, 20 feet wide and 10 feet thick shattered, sending the equivalent of 30 dump-truck loads of rock into a roadside ditch and onto the shoulder and three freeway lanes.
A boulder 5 feet in diameter landed on Ichikawa’s car, Badger said. Other rocks were 6 to 10 feet around.
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