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SR 16 - Eastbound Nalley Valley

This project is in the design phase.
Project Area Map Project vicinity in Tacoma.  

Project Photos

The demolition of the eastbound SR 16 viaduct is complete.     Taking down the original westbound Nalley Valley Viaduct
View larger image.

After Westbound Nalley Valley
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.

  After Eastbound Nalley Valley
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. 


September 2014

  • The eagerly-anticipated restriping of eastbound SR 16 to make three continuous lanes will occur, weather permitting, Tuesday and Wednesday nights, Sept. 2-3.  If all goes according to schedule, the third lane will be open for use Thursday morning, Sept. 4.
  • The I-5/State Route 16 Eastbound Nalley Valley project reached its last major milestone shortly after 1 p.m. Sunday, Aug. 17, when the Washington State Department of Transportation opened two new ramps from South Sprague Avenue to northbound and southbound Interstate 5.
  • The opening of the ramps marks the completion of the second phase of improvements to the I-5/SR 16 interchange, and sets the stage for expanded HOV lanes in Pierce County.
  • See the Olympic Region Weekly Construction and Traffic Update report for current impacts to traffic.
  • WSDOT would like to thank the public for their support during this important construction project.

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.

Project Benefits
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

Other features:

  • 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 Information

Financial Data for PIN 300509X
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $51,883
2005 Gas Tax (TPA) $54,136
Pre-Existing Funds (PEF) $7,992
Total $114,011

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
Communications Manager
WSDOT Olympic Region
5720 Capitol Boulevard SE
Tumwater, WA 98501

Neal Uhlmeyer
Construction Project Engineer
7912 Martin Way, Suite E
Olympia, WA 98516

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