SR 16 Westbound Nalley Valley Interchange
ENR's 'Best Transportation Project', 2012
Washington State Department of Transportation
McNary Bergeron & Associates
Roadways & Bridges
The SR 16 Westbound Nalley Valley Interchange project provides new westbound bridges over Nalley Valley to improve the westbound connection between Interstate 5 and SR 16. The project eliminates traffic weaves with a new direct connection from southbound I-5 to Sprague Avenue and westbound SR 16 and improves safety on the heavily-traveled roadway.
Atkinson constructed a series of ramps and overpasses to help improve traffic flow, including the Sprague Avenue on-ramp to westbound SR 16, a new eastbound SR 16 off-ramp to Sprague Avenue, and a new flyover ramp from northbound I-5 to westbound SR 16 and Sprague Avenue. In addition, the project team added full-width shoulders, new lighting, additional traffic cameras, electronic signs for traveler notification, and highway advisory radio transmitters and traffic data collectors to provide real-time traffic information online.
Because of extremely high steel prices at bid time, Atkinson proposed a Cost Reduction Incentive Proposal to change the 1,061-foot-long steel tub girder bridge to a precast concrete segmental structure — a first for the Washington State Deptartment of Transportation. Atkinson self-performed the segment precasting operations utilizing a long-line casting bed that defined the profile geometry. Using the balanced cantilever method, crews erected the 70-ton precast segments at night to minimize traffic delays on a congested I-5. Atkinson and designer McNary Bergeron also engineered a method to remove 430 linear feet of barrier from the existing viaduct to complete the Temporary Eastbound (TEB) Detour tie-in, another first for an operation like this in Washington State.
Rigorous and extensive safety training resulted in zero lost-time accidents over three years and 458,700 manhours.
The Nalley Valley project is relieving choke-points and opening up this interchange to keep people and commerce flowing.
Paula Hammond, Former Washington State Transportation Secretary