Good News for I-90/SR 18 Improvement Project, House Adds to Transportation Package

The push to get the state legislature to fund WSDOT’s plan to improve the congested and often dangerous I-90/ SR 18 interchange and widen the narrow section of SR 18 over Tiger Mountain began last October when the cities of Snoqualmie, North Bend, Black Diamond, Maple Valley and Auburn called on the legislature to improve the “critical deficiencies” of the I-90/SR 18 interchange area.

In February, when the Senate left the project off of its $15 billion Transportation Bill, Snoqualmie Mayor Matt Larson, at the urging of the Economic Development Commission, made the trip to Olympia to personally make the request in front of the House Transportation Committee – calling on them to include the project before the bill becomes final.

House Transportation Committee Member and 5th District Representative Jay Rodne, said he’s been actively pushing for I-90/SR 18 funding during the 2015 Legislative Session – calling it his “top priority.”

This week it appears Rodne got his way when the House Transportation Committee passed their version of the transportation package –  a version that included $210 million to improve the I-90/ SR 18 area.

Rodne warned earlier this month that the expensive $800 million project that would add flyover interchange ramps and widen SR 18 from Issaquah Hobart Road to I-90 would most likely have to be done in phases due to its large price tag.

According to WSDOT, if funding became available for 90/18 improvements, their first priority would be to complete design work for  the westbound I-90 to westbound SR 18 flyover ramp and the widening of SR 18 from two lanes to four between Deep Creek and I-90. It’s estimated the first phase work would cost around $180 million. The WSDOT website states the project would improve safety, reduce congestion and improve freight mobility.

Transportation Bill Next Steps

Rodne said the House Transportation package now goes to a conference committee to “iron out the differences” between the Senate version and the additions made by the House.

He said he would work hard to protect the 90/18 project and has “assurances from the Chair of the House Transportation Committee that she will safeguard our project to ensure that it is included in a final transportation package agreement.”

Rodne said he hoped to have more updates next week as the House and Senate negotiate toward a final Transportation Bill.

Why Improve 90/18? East King County Growth + Freight Traffic = Congestion Nightmare

Many blame the growth of Snoqualmie Ridge, with approximately 4,500 new homes, for the interchange congestion, but according to Mayor Larson, Snoqualmie Ridge growth only represents 17% of the impacts at the I-90/SR 18 interchange. The vast majority of the traffic pressure comes from the growth down in Maple Valley, Covington, Auburn and other areas south of I-90.

Tens of thousands of east King County residents now bypass 405 and I-5 and use SR 18 to access I-90 for jobs, while almost 18 million tons of freight is transported by semi trucks annually along SR 18, a designated T-1 Primary Freight Route and Washington Strategic Freight Corridor.

Drivers waiting at the busy intersection are often backed up onto I-90, which many drivers say is just a bad accident waiting to happen. Accidents on SR-18 at Tiger Mountain frequently close the narrow highway, making a mess of alternate traffic routes through neighboring Eastside cities.

SR 18 / I-90 Interchange.
SR 18 / I-90 Interchange.


WSDOT Design Concept for I-90/SR 18 Interchange. Photo: screenshot WSDOT website
WSDOT Design Concept for I-90/SR 18 Interchange. Photo: screenshot WSDOT website


Chevy Astro Van after being   struck by semi truck in a collision on SR 18 near I-90, on 10/28/14.  Photo:  WSP Twitter Feed
Chevy Astro Van after being struck by semi truck in a collision on SR 18 near I-90, on 10/28/14. Photo: WSP Twitter Feed


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  • Danna, great reporting as always!
    Did Jay mention if this includes the effort to relocate the weigh station at Exit 25 so that it could become a dedicated on-ramp from southbound Snoqualmie Parkway onto I-90 West? Hopefully that’s a quick fix versus all the design/building work of flyovers and lane construction on the mountain….

    1. He didn’t, but is aware that relocating the station is an easy fix. Last year he, city leaders, WSDOT and WSP had a meeting regarding relocating the station which went well…. just needed funding, as usual.

      1. I have searched for any updates and can not find any. Is the 19/90 interchange approved?

  • Does anyone know if the I90 / SR18 project ever got funded? I recently started commuting from Federal Way to Snoqualmie for work and this intersection is truly horrific. I’ve sent inquiry to WDOT but would appreciate any information you may have.

    1. It was funded in the passed $16 billion Transportation Bill – but, the funding for it is not scheduled until 2023. I know local state reps are working to get it funded sooner. But right now it appears it is going to be awhile. I agree with you that the 90/18 interchange is horrific – especially at peak hours. We had two accidents on 90 during the evening commute hours in the area where cars waiting to get on 18 get backed up onto 90. It can be very scary in this area.

      1. 2023??? That is insanity. This intersection is SO dangerous and SO congested that I think even one year is too long to wait. Yesterday there a horrific collision at the interchange. Last Friday westbound traffic on Snoqualmie Pkwy was backed up all the way to Jacobia. It took 47 minutes for me to get from Jacobia through the second light and onto WA-18, a distance of less than .5 mile. Something needs to change. What can we do to assist in getting this funded sooner?

  • Does anybody know if this was approved? I see comments from 2015 and 2016 but nothing recently. I drive by this intersection daily and see accidents everyday. The traffic is backup on the freeway daily and with cars weaving in and out of freeway traffic, end up in a tragic result.

  • Any update on any of this potential work? Kudos to whoever/however got the plastic headlight barriers installed on the median jersey barriers going up most of the hill (SR18) on the NE side of Tiger Mtn – definitely helps reduce the blinding headlights of oncoming traffic, especially when rainy. Now if only the same could be installed on the jersey barriers on the SW side of the mountain.

  • Living Snoqualmie