Full closure of SR 18 planned near Snoqualmie for I-90/SR 18 interchange project, June 4-8

Work is the last extended weekend closure of project; I-90 remains open throughout the weekend

SNOQUALMIE - After nearly four years of construction, the Interstate 90/State Route 18 new interchange project is nearly complete - but one final extended weekend paving closure is needed starting Thursday, June 4.

From 9 p.m. Thursday, June 4, to 5 a.m. Monday, June 8, traffic will not be allowed along either direction of SR 18 beneath the I-90 bridges near Snoqualmie. All right-turning ramps will remain open at the I-90/SR 18 interchange during this full closure.

People traveling through the I-90/SR 18 interchange should plan ahead, add extra time for travel, especially during peak travel times, and follow signed detours.

What to expect June 4-8

Eastbound and westbound I-90 traffic will not be affected during most of the closure, but people traveling through the area should be aware that:

• Vehicles will not be permitted on either direction of SR 18 beneath the I-90 bridges.
• Traffic on the eastbound and westbound I-90 off-ramps will only be able to turn right.
• Eastbound SR 18 traffic must use the eastbound I-90 on-ramp and follow a detour.
• Southbound traffic on Snoqualmie Parkway must use the westbound I-90 on-ramp and follow a detour.

During this closure, construction crews working for the Washington State Department of Transportation will complete final paving for the Diverging Diamond Interchange under I-90. Crews will also remove temporary barrier, install permanent impact attenuators, install guardrail, paint temporary striping, install electrical loops, place curbing and adjust stormwater drainage. This closure requires dry weather and may be rescheduled with short notice if rain is forecast.

Detour routes

People can detour around the closure using eastbound and westbound I-90 and loop around at nearby interchanges - Highpoint Way (exit 20) to the west and Southeast North Bend Way/Winery Road (exit 27) to the east.

• Westbound I-90 to westbound SR 18: Continue westbound on I-90 to exit 20, High Point Way, loop back to eastbound I-90 and exit at SR 18/Snoqualmie Parkway.
• Westbound SR 18/Snoqualmie Parkway to eastbound I-90: Use the westbound I-90 on-ramp to exit 20, High Point Way, and loop back to eastbound I-90.
• Eastbound SR 18 to westbound I-90: Use the eastbound I-90 on-ramp to exit 27, North Bend/Snoqualmie (Winery Road), and loop back to westbound I-90.
• Eastbound I-90 to Snoqualmie Parkway: Continue eastbound on I-90 to exit 27, North Bend/Snoqualmie (Winery Road), loop back to westbound I-90 and exit at SR 18/Snoqualmie Parkway.
• Eastbound SR 18 to northbound Snoqualmie Parkway: Use the eastbound I-90 on-ramp to exit 27, North Bend/Snoqualmie (Winery Road) loop back to westbound I-90, then exit at SR 18/Snoqualmie Parkway.
• Southbound Snoqualmie Parkway to westbound SR 18: Use the westbound I-90 on-ramp to exit 20, High Point Way, loop back to eastbound I-90, then exit at SR 18/Snoqualmie Parkway

To help keep traffic moving, the Preston/Fall City exit on westbound I-90 should be used primarily by local traffic. Travelersrs can potentially save time by using the signed detour at Southeast High Point Way or by using alternate routes.

Freight traffic should not use Issaquah city streets or Issaquah-Hobart Road, which are not suitable for semi-trucks. Similarly, eastbound SR 18 freight traffic cannot use Issaquah city streets to access I-90.

Additional closures planned

Once all final paving is completed, there will be a series of smaller closures of SR 18 scheduled to install permanent lane markings throughout the project area. These will not be full closures.

Busy construction weekend: Northbound I-5 Ship Canal Bridge also closed

The Revive I-5 Ship Canal Bridge preservation project also will have a full closure of the northbound freeway from I-90 to Northeast 45th Street the weekend of June 5-8.

All northbound traffic will use the I-5 Express Lanes. During this closure, crews will remove construction barriers to reopen all lanes of northbound I-5 for the upcoming soccer tournament in Seattle. They'll also restore the I-5 express lanes to their normal operating schedule. The northbound freeway has been reduced to two lanes on the Ship Canal Bridge for the past several months.

People travelling in the Seattle and Snoqualmie areas should plan for long delays and heavy traffic conditions.

Project history

The I-90/SR 18 Interchange Improvements and Widening project broke ground Sept. 8, 2022, and constructed the second diverging diamond interchange in Washington.

This project has significantly reduced travel and wait times at the I-90/SR 18 interchange, which is one of the busiest in the state. In addition to the new interchange, the project built three new bridges, widened more than 2 miles of SR 18 south of I-90 to four lanes - two in each direction - and removed six barriers to fish passage in waterways.

Future widening planned

Another project to continue widening SR 18 from Deep Creek (milepost 26) to Tiger Summit (milepost 24) as well as making improvements at the Issaquah-Hobart Road interchange with SR 18 is currently in design. It is scheduled to begin construction as early as 2030.

Real-time travel information is available via the WSDOT mobile app, the WSDOT Travel Center Map or by signing up for WSDOT's email updates.