State Route 18 will be reduced to two lanes in each direction at the Interstate 90 interchange beginning Wednesday, July 17, with the elimination of the center turn lane near the city of Snoqualmie.
A new traffic signal will help drivers navigate the changed layout, which will last throughout the construction of a new diverging diamond interchange, scheduled to open late this year.
Beginning at 9 p.m. Wednesday, July 17, contractor crews working for the Washington State Department of Transportation will close the far west lane of SR 18 to create a safe work zone for the I-90/ SR 18 interchange improvements project.
Westbound lanes will then shift to the left, resulting in no center left turn lane between eastbound and westbound SR 18.
The center turn lane is the lane at the interchange between eastbound and westbound SR 18 that vehicles currently use to turn left onto the I-90 on-ramps. This change is in place until the project is completed.
Traffic will be allowed in all lanes, but people using the left lanes in each direction should be prepared for stopped vehicles. These vehicles must yield to oncoming traffic before turning left onto the eastbound and westbound I-90 on-ramps. A flashing yellow light will indicate when turning; vehicles must yield.
This change will remain in effect until the new diverging diamond interchange opens in late 2024.
WSDOT asks drivers to remain patient and distraction-free while people adjust to the new traffic pattern.
Diverging diamond interchange
WSDOT identified the new diverging diamond interchange, which is expected to open in late 2024, in 2016 as the preferred way to improve efficiency and safety at the busy interchange.
Once completed, it will be the second diverging diamond interchange in the state. To improve traffic flow, it will allow through traffic and left turns at the same time.
[Information provided by the Washington State Department of Transportation]
The $188 million project also is widening SR 18 to two lanes in each direction for approximately two miles south of I-90.
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.
Comments
Any chance of getting a diagram of this? It’s kind of hard to understand which lanes are affected?
I asked for one, but they said it was unavailable. Basically, it is the two left turn lanes onto I90 after you go under the freeway.
I think some of the confusion is that WSDOT considers Hwy 18 a E/W highway, but at this location the hwy is N/S. There is only a single SB 18 turn lane onto I-90 EB at that intersection (far left), a through lane (middle), and an additional SB merge lane that ends shortly after the intersection (far right). The way I read this, the hwy will be reduced to a single SB lane, with a shared turn lane, and no merge lane.
If true, this will cause even more extensive backups on Snoqualmie Parkway approaching I-90.
What’s not clear is if NB Hwy 18 is also impacted as it has a similar alignment, the article kind of makes it sound that way. I’m also curious what will happen to the second turn lane from WB I-90 to SB Hwy 18.