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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. 


July 2014

  • At 9 p.m. on Monday, July 28, crews will close the left southbound lane of I-5 near the interchange for drainage work. The lane will reopen by 6 a.m. Tuesday, July 29.

  • At 11 p.m. on Wednesday, July 30, crews will close the South 38th Street on-ramp to northbound I-5 and the City Center for striping. The ramp will reopen by 4 a.m. Thursday, July 31.

  • At 11 p.m. on Thursday, crews will close two ramps: South 38th Street on-ramp to northbound I-5 and the City Center; and
    northbound I-5 exit (#133) to the City Center. Signed detours will be provided for the closed ramps. Both ramps will reopen by 4 a.m. Friday, August 1.

  • On Saturday, July 12, crews opened a new eastbound State Route 16 ramp connection to northbound Interstate 5. The new ramp is one of many improvements being completed in WSDOT’s I-5/SR 16 Eastbound Nalley Valley project.

  • Motorists on eastbound SR 16 previously merged with other traffic as they enter the northbound I-5 collector/distributor that runs parallel to mainline northbound I-5. The new ramp gives motorists a dedicated lane on the collector/distributor, eliminating the need to merge with other traffic.
  • Another notable change with the new ramp is that the eastbound SR 16 split to northbound and southbound I-5 occurs further west than it occurred previously, so motorists will need to move into the correct lane sooner.

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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