SEATTLE — Decades ago, when construction crews carved a highway through Snoqualmie Pass, site of an ancient Indigenous trail, they also created a risk that the hills would push back.
Now the Washington State Department of Transportation is aiming to prevent rockslides along westbound Interstate 90 by shaving away a ledge that protrudes toward traffic at milepost 42, the Tinkham Road area.
WSDOT frequently breaks, binds or even blows up cliffs that endanger fast-moving traffic, but it’s unusual to block the right lane for months on Washington’s primary cross-state roadway, as a couple million travelers will notice this summer. Get ready to merge left.
Rockslide prevention project will close part of I-90
A $6 million state project will shave a protruding ledge and remove loose rocks and woody debris along westbound I-90.
Sources: Esri, Washington State Department of Transportation (Mark Nowlin / The Seattle Times)
WSDOT closed the right lane in early May so contractors could set out steel shipping containers and concrete barriers as a precaution should stones tumble. Now they’re scraping away loose sediment and woody debris before installing metal nets and deep dowels, spokesperson Meagan Lott explained. Granite Construction is working under a $6 million contract and should finish the 1-mile stabilization this fall, she said.
The freeway from Snoqualmie Pass to North Bend is already a harrowing place, as tailgaters routinely surpass 80 mph downhill, alongside semis, recreational trailers and slower drivers. WSDOT recently sounded alarms about work zone crashes exceeding three per day statewide, including 28 serious injuries and 10 deaths in 2023.
Fortunately, there haven’t been significant collisions or delays at the I-90 work zone, Lott said.
“I think it’s pretty well marked,” said State Patrol Trooper Rick Johnson, a spokesperson based in Bellevue. Five troopers and a sergeant are assigned between North Bend and the pass to crack down on the area’s rampant speeding and aid motorists, he said. Wide lanes, and a lack of ice in springtime, allow for safe travel in that spot, Johnson said.
On a busy Sunday, about 28,000 westbound vehicles pass through this stretch and 15% exceed 76 mph, according to WSDOT’s public analytics for May 5.
What you’ll see is reminiscent of the 2017 scene in Union Gap near Yakima, where a crack in Rattlesnake Hill prompted WSDOT to set shipping containers next to I-82, which remained open. Yakima County closed adjacent Thorp Road.
This year’s I-90 job is part of an organized “unstable slope management plan” dating to the mid-1990s, Lott said. Geotechnical specialists nominated I-90/Tinkham Road for a list of potential slide zones a decade ago, but since there have been no rockfalls there, crews can finish preventive work now instead of answering an emergency later, she said. This year’s other project will fasten netting along Highway 17 north of Soap Lake, in the arid Columbia Basin.
In 2005, three people were killed when a boulder fell on their car 2 miles west of Snoqualmie Summit while they were traveling home from a concert at the Gorge.
Nets, nails and barriers are commonplace through Snoqualmie Pass, but they are usually installed far enough away from the freeway that construction crews can keep lanes open, except when explosives are detonated to shake out rubble or snow.
Motorists might remember a lane closure on I-90 in 2022, but that was a much different project, caused by severe potholes at milepost 32 in North Bend. Instead of more patching, WSDOT chose to block the right westbound lane until crews could repave it during a multi-road regional contract.
Meanwhile, roadway panel replacements are underway in the eastbound direction, a pinch point that created congestion Memorial Day weekend a few miles before the pass. Single-lane closures are planned through October as crews deal with multiple rough spots between North Bend and Hyak. Road panels have cracked and eroded faster than WSDOT can replace them.
Billy Hetherington, president of the Washington State Good Roads & Transportation Association, said he’s glad to see recent I-90 construction, including the Keechelus Lake wildlife crossing, widenings east of Hyak, panel repairs, and a $79 million bridge deck replacement across the Columbia River in Vantage. “We think that’s great, if they’re going to be proactive,” he said. “We still feel it’s a drop in the bucket compared to what we need.”
This year, Transportation Secretary Roger Millar told legislators the state is dedicating just one-third of the $1.5 billion per year that’s needed to keep Washington’s roads and bridges in good repair.
In the same right lane blocked by I-90 hillside work, old pavement panels are listing and uneven. Rather than level those now, WSDOT is short on money and expects to reopen the lane in poor condition, Lott said. “Motorcyclists use extreme caution” or similar warning signs will greet travelers passing through.
