The 11 years and three construction projects that took place to increase capacity on the Nalley Valley Viaduct — the interchange connecting Interstate 5 and State Route 16 in Tacoma — have been 11 long years for travelers in the area. But the construction will soon wrap up as contractor Skanska plans to open new connected high-occupancy vehicle (HOV) lanes between the two highways for owner Washington State Dept. of Transportation. 

The mid-November opening marks the completion of the third and final project as part of the $1.6 billion, 11-year project to remake the entire interchange. 

“We are thrilled to have HOV lanes on this vital interchange open to travelers,” said John Wynands, WSDOT regional administrator, in a statement. “They are a key transportation component that keeps people moving and improves trip reliability for those who choose to share the ride. At the end of the day, that is what this project is all about.” 

The Nalley Valley Viaduct originally opened in 1971 with 40,000 daily users. By 2019 that number more than tripled to an average daily use of 133,000 vehicles. To bring additional capacity to the viaduct, first crews completed a SR 16 westbound improvement project in 2011 and then a SR eastbound project in 2014. The I-5 and SR 16 realignment and HOV connection project is the third piece to the viaduct’s increased capacity. 

With the Nalley Valley Viaduct portion wrapping up, all eyes turn to the final piece of the Tacoma and Pierce County HOV system, the I-5 Portland Avenue to Port of Tacoma Road Southbound HOV project that will build a new southbound I-5 bridge over the Puyallup River and allow connections for HOV lanes, once complete, between Tacoma and Fife. 

The $324 million contract underway to design and build a wider I-5 between the Tacoma Dome and Puyallup river requires a new bridge over the river to carry the southbound lanes of the interstate. Guy F. Atkinson Construction is handling the project.

When the new Nalley Valley Viaduct HOV connections open, travelers who use the northbound I-5 HOV lane will temporarily merge into mainline traffic near the Yakima Avenue overpass, a configuration that will remain in place until the southbound I-5 Puyallup River Bridge project completes sometimes in 2021. When that happens, the entire HOV system will be open, with HOV lanes extending from Gig Harbor on SR 16 west of Tacoma onto I-5 through Tacoma and Fife and continuing north through King County. 

Follow Tim Newcomb on Twitter at @tdnewcomb