WSDOT Projects

View entire map. This project will build a new westbound SR 16 structure.

Existing Interchange

Proposed Interchange

This computer-enhanced photo represents the first project of three that will replace and improve the I-5/SR 16 Nalley Valley interchange. Benefits of this first project, which will be under construction between 2008 and 2011, include building a new westbound Nalley Valley viaduct, preparing for future connections of HOV lanes between I-5 and SR 16, rebuilding ramps connecting SR 16 to and from Sprague Avenue, replacing ramps from I-5 to westbound SR 16, constructing stormwater collection and treatment facilities, upgrading signing and illumination, and installing communications devices into the highway to help WSDOT manage traffic and relay traffic conditions to the public and media via WSDOT's website.

Project Facts

• The current Nalley Valley viaduct carries about 131,000 vehicles a day (both directions).
  
• The new Nalley Valley interchange will have four tunnels and nearly 150 columns.
  
• At its widest point, the Nalley Valley structures will span 358 feet across and have 14 lanes. At its tallest point, the Nalley Valley structure will be 100 feet off the ground.

Why is WSDOT rebuilding the Nalley Valley Viaduct?
WSDOT is in the process of building HOV lanes on I-5 and SR 16, which means that many bridges within the project limits need to be widened to accommodate the new lanes.  The Nalley Valley Viaduct is no exception - it must be widened for the new HOV lanes.  However, the existing Nalley Valley structures are too narrow to carry additional lanes. The unique tetrapod piers that support the existing Nalley Valley Viaduct prevent WSDOT from widening the structure. 

The End Result

As the first of three projects to reconstruct the Nalley Valley, this large project will build quite a few improvements on SR 16 across Nalley Valley:  

• Constructs new westbound viaduct bridges over Nalley Valley
• Builds new ramp from southbound Sprague Avenue to eastbound SR 16 (will not be open to traffic until late 2013)
• Builds new direct connection from southbound I-5 to Sprague Avenue and westbound SR 16, eliminating much of the weaving motorists currently see in that area
• Builds new Sprague Avenue ramp to westbound SR 16
• Builds new eastbound SR 16 exit to Sprague Avenue
• Builds new flyover ramp from northbound I-5 to westbound SR 16 and Sprague Avenue
• Prepares for Eastbound Nalley Valley project

Project Benefits

Each of the three Nalley Valley projects will fit together to completely reconstruct the Nalley Valley.

Once all three projects are complete, the new Nalley Valley interchange will:

• Add HOV lanes in both directions connecting SR 16 and I-5
• Increase the number of general-purpose lanes in both directions
• Eliminate the current traffic weave that is created when I-5 southbound traffic merges into SR 16 traffic taking the Sprague Avenue exit
• Add traffic cameras, electronic signs for traveler notification, highway advisory radio broadcast transmitters, and traffic data collectors that send data to traffic management centers for monitoring and provide traffic information for the Web and 5-1-1.

What is the project timeline?

• Late 2008 - Construction Begins
  Crews will start building a new westbound bridge north of the current viaduct.  This is the first of three projects to rebuild the Nalley Valley Viaduct and all connecting ramps between SR 16 and I-5.  Sprague Avenue near SR 16, and the Sprague Avenue/SR 16 ramps, will be closed for at least two years.  The extended ramp closures will allow crews to rebuild the ramps and Sprague Avenue approaching the ramps more efficiently, saving time and money.
• 2009-2011 The I-5/SR 16: Westbound Nalley Valley Project is under construction. 
• 2011 - The project will be complete and westbound traffic shifted onto the new westbound structure. Once the westbound project is complete, crews will begin building new eastbound viaduct structures. 
• 2011-2013 - The I-5/SR 16: Eastbound Nalley Valley project is under construction.  This is the second of three projects to reconstruct the Nalley Valley.  This second project focuses on replacing the eastbound viaduct and various ramps connecting SR 16 and I-5.
  
• 2020 - 2023 - I-5/SR 16: HOV Connectors project will be under construction.  This is the final of three projects to reconstruct the Nalley Valley.  In this project, crews will build ramps and other structures that will connect HOV lanes on SR 16 and I-5. 

Public Involvement
Your thoughts and opinions are important to us. Public involvement for this project has been underway since 1993. During this time, WSDOT and the project partners have held several stakeholder meetings and public open houses.

We have met with the Nalley Valley Business Coalition and are coordinating with the City of Tacoma and Sound Transit. 

Learn more about our public outreach and involvement efforts.

Environmental Protection
We completed and approved an Environmental Assessment in 1999 to fulfill National Environmental Policy Act (NEPA) requirements for the Tacoma/Pierce County HOV Program. That document encompassed the HOV projects in the Nalley Valley portion of the HOV Program on both SR 16 and I-5. We are updating the environmental documents, as required by NEPA and the State Environmental Policy Act (SEPA), to address current environmental conditions and to acknowledge changes in environmental regulations since 1999. We will evaluate project impacts to threatened and endangered species, wetlands, water quality, air quality, cultural resources, and others.

All of the HOV improvements in the Nalley Valley area will be done within the existing freeway corridor.

Some of the environmental mitigation, specifically wetland mitigation, will be done elsewhere because opportunities for wetland mitigation in the Nalley Valley area are very limited. We are working with the City of Tacoma and other resource agencies to identify mitigation that will provide appropriate ecological benefits to offset wetland impacts.

Compliance with the Endangered Species Act (ESA) is a major focus of the environmental program. The ESA provides protection for threatened and endangered aquatic and terrestrial plants and animals. For the Tacoma/Pierce County HOV Program, the effects of storm water runoff on fish and their habitat is a high-priority concern. We are developing storm water treatment designs to meet current standards and to satisfy the current stringent requirements to protect water quality and habitat for aquatic species.

We are working with local, state, and federal agencies to ensure that our project protects our environmental resources.
Please visit the WSDOT Environmental Services Web site for more information.

Increasing safety is one of our priorities
In addition to a wider Nalley Valley Viaduct, the project will add merge lanes and other features to improve safety.

Will this project impact tribal resources?

At WSDOT we seek to address the concerns of the tribal nations using the process outlined in Section 106 of The National Historic Preservation Act and the WSDOT Tribal Consultation Policy adopted in 2003 by the Transportation Commission as part of the WSDOT Centennial Accord Plan.

The Puyallup Tribe of Indians has been a significant stakeholder in the development of the Tacoma/Pierce County HOV Program.

Beginning in 1998, the Puyallup Tribe has been involved in defining projects in Tacoma and Fife, providing direct input to project staff during two presentations in 1999. When the next design phase began in 2002 — widening I-5 from the Tacoma Dome to Fife — the tribe was invited to participate in a project oversight committee whose focus will be to review staff work and provide input on design alternatives.

For more information visit our WSDOT Tribal Liaison Web site.

Financial Information

This project is funded through the following sources:

How can I get more information?
Contact:
Claudia Cornish, HOV Communications Manager
WSDOT Tacoma/Pierce County HOV Office
P.O. Box 47376
Olympia, WA 98504-7376
Phone: 360-709-8130 
Email: cornishc@wsdot.wa.gov

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