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SR 16 - Westbound Nalley Valley - Complete June 2011

Project Area Map Project vicinity in Tacoma. View entire map. 

Project Photos

New Westbound Interchange
Interchange after Westbound Nalley Valley construction. View larger graphic.


October 2014

Why is WSDOT rebuilding the westbound I-5/SR 16 Nalley Valley interchange?
To increase safety, improve mobility and reduce congestion, WSDOT rebuilt the I-5/SR 16 Nalley Valley interchange. The original Nalley Valley interchange was too narrow to carry additional lanes and the unique structure-type prevented widening.

Reconstruction of the interchange was staged to keep people and goods moving.

The westbound Nalley Valley construction contract built a new westbound connection between SR 16 and I-5. The new westbound viaduct and associated ramps opened to traffic in June, 2011. 

A sister project, Eastbound Nalley Valley, reached its last major milestone in Aug. 2014.  In that project, crews built a new eastbound viaduct, demolished the original viaduct and completed all ramp work at the SR 16/Sprague Avenue interchange.  

A third project in which crews will build direct-connect HOV ramps between I-5 and SR 16 HOV lanes, and a new HOV viaduct, will be built between 2016 and 2019.

This project 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
The Westbound Nalley Valley project improves the westbound connection between I-5 and SR 16 by: 

  • Constructing new westbound bridges over Nalley Valley.
  • Eliminating traffic weave with a new direct connection from southbound I-5 to Sprague Avenue and westbound SR 16.
  • Building a new Sprague Avenue on-ramp to westbound SR 16.
  • Building a new eastbound SR 16 off-ramp to Sprague Avenue.
  • Building new flyover ramp from northbound I-5 to westbound SR 16 and Sprague Avenue.
  • Improving safety with full-width shoulders and new lighting.
  • Adding traffic cameras, electronic signs for traveler notification, highway advisory radio transmitters and traffic data collectors to provide real-time traffic information for the Web and 5-1-1.

Project Benefits
This project provided new lanes, reduced traffic weaves and dedicated ramps to Sprague Avenue. The result is improved safety, reduced congestion and increased mobility at the northbound and southbound I-5 connections to westbound SR 16.

What is the project timeline?
WSDOT awarded the construction contract ($119.9 million) to Renton-based Guy F. Atkinson Construction, LLC, on Oct. 6, 2008.

Construction started in January 2009. The project opened to traffic in June, 2011.

This project and two more in the Tacoma/Pierce County HOV Program completely rebuild the Nalley Valley interchange. Learn more about the Tacoma/Pierce County HOV Program.

Financial Information

This project is funded through the following sources:

  • 2003 Gas Tax (Nickel Funding) - $149,278 million
  • Federal - $8,972 million
  • State - $11,642 million
  • Local - $0.404 million
  • Total Funding Available From All Sources - $170,296 million

While the HOV Program scope has remained the same, the work delivery plan has been modified over time to increase construction efficiencies and maximize resources. The funding listed above represents the current delivery plan for this project.

How can I get more information?
Claudia Bingham Baker
Communications Manager
WSDOT Olympic Region

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