Safety upgrades coming to dangerous SE 104th/SR 18 intersection near Snoqualmie as part of interchange improvement project

The I-90/SR 18 interchange improvement project near Snoqualmie will also bring needed improvements to the often dangerous SE 104 Street / SR 18 intersection located just west of the busy interchange.

As part of overall improvements to the congested interchange, the Washington State Department of Transportation (WSDOT) will also make changes to the SE 104th and SR 18 intersection.

It is often difficult and dangerous for residents living near Echo Lake get into and out of the area using SE 104th due to SR 18 congestion and roadway speed limit.

The WSDOT project page states, “The proposed configuration will improve safety for drivers entering and exiting the highway at SE 104th Street, as well as benefit traffic flow through the I-90/SR 18 interchange.”

A proposed two-way stop, a protected left-hand turn lane barrier, U-turn options and a new flashing “turning traffic ahead” signal are all proposed improvements for the SE 104th and SR 18 area. [See image below]

WSDOT said the project will be a design-build contract, authorizing the contracted firm to decide if the state’s proposed improvement plan is the best solution for SE 104th – or ‘to design a different, more cost-effective option.’

That essentially means the ultimate solution could look different than the one currently proposed by WSDOT.

WSDOT’s Proposed SR 18/ SE 10th Street Intersection Improvements

  • Widen SR 18
  • A barrier protected left-turn lane on WB SR 18 to Southeast 104th Street
  • Barriers on SR 18 and Southeast 104th Street
  • A signalized U-turn in the SR 18 median just before the I-90/SR 18 interchange
  • Traffic safety beacon prior the SR 18/SE 104th Street intersection to alert approaching traffic to cars turning onto SR 18

According to WSDOT, 90/18 interchange construction is tentatively scheduled to begin in 2021, with the new diverging diamond interchange opening in 2023. The SR 18 lane expansion part of the project begins once the interchange work is finished

SR 18 and SE 104th intersection. PC: Googlemaps

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  • two comments
    1. it appears there is space right near the freeway for a full u-turn avoiding the need for a light and slowing down traffic. why isn’t that being done?
    2. it appears there is no curb on the 4 lane highway except the left turn before 104th. what? if true: 1. means head on collisions remain a threat; 2. to save time, people coming out of 104th will go across the road going over the double lines–a more dangerous situation than exists now.

  • Living Snoqualmie