May 2012
- We are designing improvements to the I-90/SR 18 interchange and working on environmental documentation for the proposed interchange.
- We are also coordinating I-90/SR 18 interchange improvements with the Federal Highway Administration.
- This project is currently unfunded.
We are developing plans to widen SR 18 to two lanes in each direction between Issaquah Hobart Road and I-90 and to rebuild the I-90/SR 18 interchange.
Why is WSDOT
improving the I-90/SR 18 interchange and widening seven miles of SR 18 from Issaquah Hobart Road to I-90?
Issaquah Hobart Road to I-90 is the last segment of a multi-phase project to widen 21 miles of SR 18 to four lanes from Auburn to I-90. The widening is necessary to increase safety and improve mobility through the entire SR 18 corridor.
This segment of the project will include an expanded I-90/SR 18 interchange and a new interchange at the Tiger Mountain Summit.
We are focusing our efforts on expanding the I-90 interchange first, followed by SR 18 widening.
Additional improvements include extending truck climbing lanes, realigning sharp curves to improve driver sight distance and to help them safely maintain their speed, improving fish passage at stream crossings, new drainage facilities, and improving accommodations for wildlife crossings.
The End Result
When this project is complete, drivers will travel on an expanded I-90/SR 18 interchange and a four-lane divided highway with truck climbing lanes between Issaquah Hobart Road and I-90.
Project Benefits
• Safety – This project will reduce the likelihood of head-on collisions by building a 51-foot median to divide opposing directions of traffic. Where the mountainous terrain and/or significant environmental impacts make the addition of the full median too costly, we will use median barrier to separate traffic.
Find out how previous SR 18 widening projects are improving safety (pdf 343kb).
• Congestion Relief – We will increase the capacity of the highway by adding one lane in each direction. Truck climbing lanes will speed travel over the Tiger Mountain Summit by providing a separate lane for slow moving traffic. An improved I-90/SR 18 interchange will enhance traffic flow in a rapidly growing area.
• Environment – This project will build drainage facilities to capture and clean highway runoff, and replace narrow culverts with wider culverts or bridges to help fish swim up and down streams. WSDOT will strive to avoid excessive impacts to wetlands and other sensitive areas. When wetlands cannot be avoided, WSDOT will create new wetlands or enhance existing ones to compensate for the impact. WSDOT will also be studying ways to protect wildlife in the area, including the construction of new wildlife crossings.
• 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. The increased capacity of the highway will help keep freight moving.
What is the project timeline?
The Nickel Funding Package passed by the 2003 Legislature provided $6 million to complete the environmental review and preliminary design for the I-90/SR 18 interchange and early design for SR 18 widening. During this process we chose a preferred route for the highway and preferred design for the expanded interchange.
Full project design and construction is currently unfunded. If funding becomes available and work progresses without interruption, we expect to complete the expanded I-90/SR 18 interchange about four to five years after we receive funding.
Financial Information
| Financial Data for PIN 101822A, 101826A |
| Funding Source |
Amount ($ in thousands) |
| 2003 Gas Tax (Nickel Funding) |
$6,000 |
| 2005 Gas Tax (TPA) |
$0 |
| Pre-Existing Funds (PEF) |
$41 |
| Total |
$6,041 |
|
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?
Contact:
Design Engineer Sharif Shaklawun
15700 Dayton Avenue North
Seattle , WA 98133
Phone: 206.440.4272
E-mail:ShaklaS@wsdot.wa.gov
WSDOT Communications Meghan Pembroke
15700 Dayton Ave. N
Seattle, WA 98133
Phone: 206-440-4704
E-mail: pembrom@wsdot.wa.gov
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