Project vicinity in Tacoma.
The demolition of the eastbound SR 16 viaduct is complete.
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This aerial photo shows the completed westbound Nalley Valley structures (lighter pavement on the right). The facility opened to traffic in June 2011. View larger image
Artist's rendering of Nalley Valley interchange after both westbound and eastbound work is complete. This will complete two of three projects to improve and expand the I-5/SR 16 interchange, including the Nalley Valley Viaduct.
The final phase of construction
on this interchange is not scheduled for construction until 2020. In that third phase, crews will build HOV direct-access connections and an HOV bridge between the two new viaduct structures.
Single-lane closures will occur between 6 a.m. and 6 p.m. each weekday on South Center Street, South Tacoma Way, and South Sprague Avenue.
This project received $7.8 million from the American Recovery and Reinvestment Act to accelerate preliminary engineering.
Why is WSDOT
building a new eastbound Nalley Valley Viaduct?
The original Nalley Valley structures were too narrow to carry additional lanes. The unique tetrapod piers that supported the existing Nalley Valley Viaduct prevented widening the structure.
The I-5/SR 16 Eastbound Nalley Valley project is the second of three projects that rebuild the Nalley Valley Viaduct. The first project, Westbound Nalley Valley, is now open to traffic. The third project, the I-5/SR 16 HOV Connectors, will be built between 2020 and 2023 and will provide HOV connections between I-5 and SR 16.
Reconstruction of the Nalley Valley interchange is part of a series of projects to reduce congestion, improve safety and add HOV lanes in Pierce County. Learn more about the Tacoma/Pierce County HOV Program.
The End Result
All eastbound SR 16 traffic has been moved onto a new and improved eastbound viaduct structure. The project also will open a new ramp between South Sprague Avenue and eastbound SR 16.
In addition, both the new eastbound and westbound viaducts create ramp connections that will be used in the third and last phase of viaduct work. In that third project, crews will build HOV direct-access ramps between SR 16 and I-5 HOV lanes, and build an HOV bridge between the eastbound and westbound viaduct structures.
As the second of three projects to reconstruct the Nalley Valley, this large project will add quite a few improvements on eastbound SR 16 across Nalley Valley.
- Widens shoulders.
- Improves ramp alignments and curves. Improves lighting.
- Additional capacity improves traffic flow.
- Reduces conflicting traffic movements or weaving areas.
- Improves stormwater treatment;
- Restores wetlands at the Tacoma Nature Center
Intelligent Transportation System (ITS):
- Adds traffic cameras.
- Improves electronic signage for traveler notification.
- Adds highway advisory radio capacity.
- Installs traffic data collectors. WSDOT uses the data to provide traffic information to the public
- Demolishes the existing viaduct in stages;
- Shifts the existing ramp from southbound I-5 to South 38th Street to accommodate tunnel construction;
- Builds a new ramp from South Sprague Avenue to southbound I-5
- Builds a new ramp from South Sprague Avenue to northbound I-5
What is the project timeline?
- 2009 - Design work began. Project received federal stimulus funds for preliminary engineering.
- 2011 - I-5/SR 16: Eastbound Nalley Valley design work was completed. The construction contract was awarded to Mowat Construction of Woodinville, and construction began in November 2011.
- 2014 - The eastbound viaduct and two ramps from southbound Sprague Avenue to eastbound SR 16 will open to traffic. One ramp will lead to northbound I-5 and the other will lead to southbound I-5.
|Financial Data for PIN 300509X
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|2003 Gas Tax (Nickel Funding)
|2005 Gas Tax (TPA)
|Pre-Existing Funds (PEF)
Project signage will reflect the cost of construction engineering, project bid award and sales tax.
How can I get more information?
Project Information Toll Free
Claudia Bingham Baker
WSDOT Olympic Region
5720 Capitol Boulevard SE
Tumwater, WA 98501
Construction Project Engineer
7912 Martin Way, Suite E
Olympia, WA 98516
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