- The design office is now completing preliminary and early design work.
- Environmental review work for a new direct ramp from westbound I-90 to westbound SR 18 near North Bend is complete. The new ramp would help relieve congestion and improve traffic flow at the busy interchange.
- We do not have funding at this time construct this project.
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Why is WSDOT
designing a direct ramp from westbound I-90 to westbound SR 18?
Our plan for this area includes additional direct freeway-to-freeway ramps and improvements to help control traffic at I-90 on- and off-ramp intersections. We also plan to widen seven miles of SR 18 from Issaquah-Hobart Road to I-90. These improvements would make up the last segment of a multi-phase project to widen 21 miles of SR 18 to four lanes from Auburn to I-90. We do not have funding to design or construct these improvements.
We originally estimated it would cost $600 million to improve the interchange and widen SR 18 in 2005 dollars. Inflated and adjusted to the present, we estimate it will cost $750 million to improve the entire interchange and widen SR 18 from two lanes to four with a concrete barrier separation between Deep Creek and I-90.
We are completing early environmental and design work for:
- Widening SR 18 between Deep Creek and I-90 from two lanes to four, with a concrete barrier separating eastbound and westbound lanes.
- A new direct ramp from westbound I-90 to westbound SR 18. The direct ramp would help improve traffic flow at the interchange by reducing congestion at the signalized intersections on either side of I-90. Drivers would not have to travel through several signals in order to move from westbound I-90 to westbound SR 18, which would reduce travel times for commuters and freight traffic. The new ramp would reduce delays for eastbound I-90 to Snoqualmie Parkway traffic; drivers would see additional green time at the off-ramp signal.
Widening the highway and improving the interchange will improve safety and improve traffic flow and mobility for commuters and freight. We do not have funding to complete design work or build the new ramp. We estimate the cost of the new flyover ramp and the widening of SR 18 would be $180 million.
The End Result
The widening of SR 18 and a new interchange between westbound SR 18 and westbound I-90 will improve capacity and help keep freight and commuters moving.
• Safety – A direct ramp from westbound I-90 to westbound SR 18 and the widening of SR 18 will reduce the risk of congestion-related collisions.
Find out how previous SR 18 widening projects are improving safety (pdf 343kb).
• Congestion Relief – The widening of SR 18 will increase capacity and enhance traffic operations. The new direct ramp would reduce travel times and improve traffic flow at the busy SR 18/I-90 interchange. The new ramp would relieve pressure at the signalized intersections on either side of I-90, particularly for eastbound I-90 drivers headed to the Snoqualmie Ridge community via eastbound SR 18.
• Freight Mobility – SR 18 is an important regional and national truck route between eastern Washington and beyond and Sea-Tac Airport and the Port of Tacoma. Widening the highway between Deep Creek and I-90, along with improving the connection between westbound I-90 and westbound SR 18 will help keep freight moving.
What is the project timeline?
The Nickel Funding Package passed by the 2003 Legislature provided $6 million to complete the environmental review and preliminary design for the I-90/SR 18 interchange and early design for SR 18 widening.
Full project design and construction is currently unfunded. If funding becomes available, WSDOT's 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.
The Nickel Funding Package passed by the 2003 Legislature provided $6 million to complete the environmental review and preliminary design for the I-90/SR 18 interchange and early design for SR 18 widening from Issaquah Hobart Road to I-90.
Note: Final project design, right of way acquisition, and project construction are not funded.
How can I get more information?
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