Tuesday, March 3, 2020

Emergency repair – and weekend closure – will preserve westbound SR 18 west of Tiger Mountain summit

Update
Emergency repairs on westbound SR 18 were finished at about 6:30 p.m. Sunday, March 8. The highway is now open in both directions.
By Tom Pearce

The drenching rains that started 2020 may have subsided, but we’re still dealing with the aftermath of all the water that soaked our state and highway system – including on State Route 18.

The rain damage in western Washington included an early February slide under the shoulder of SR 18 about 1.5 miles west of the Tiger Summit Trailhead. To repair damage from this slide, at 8 p.m. Friday, March 6, contractor crews will close westbound SR 18 from Tiger Mountain Summit to Issaquah-Hobart Road until noon Tuesday, March 10. During the closure, travelers will detour via westbound I-90, I-405 and SR 167 or I-5.
Contractor crews will repair westbound SR 18 between Tiger Mountain Summit and Issaquah-Hobart Road. This will require closure of the westbound lane from the evening of
Friday, March 6, until noon on Tuesday, March, 10.

The Feb. 6 slide washed away soil under a wide spot of the westbound shoulder between Interstate 90 and Issaquah-Hobart Road. Part of the pavement collapsed, but damage did not reach the shoulder – yet.

The highway is fine, though if you travel in one of the 27,000 vehicles that goes through that area each day you probably have seen our orange traffic barrels on the shoulder.
When the soil eroded away under the SR 18 shoulder, the guard rail was left
hanging and pieces of the asphalt turnout collapsed.

To prevent any further damage, we need to close the westbound lane so crews have enough space to safely dig out saturated soil from under the damaged turnout near the shoulder. When they reach solid ground, which we expect they’ll find about 10 feet down, the crews will place rock to fill and support the area, then repave it.

We know this will be an inconvenience for people who rely on this important route between Snoqualmie Pass and south King County or Tacoma. This relatively quick restoration allows us to preserve the highway and avoid a major problem should more of the hill slide away from under the roadbed before we can fix it. That could cause a long-term closure, perhaps of both directions of SR 18 – something we all want to avoid.

Thank you for your patience as we work to preserve this vital roadway!