Project of the Week: Smashing the SR 16/I-5 bottleneck

By guest blogger Joe Irwin

Traffic that once ground to a standstill as 131,000 vehicles drove through Pierce County will run freely Sunday, June 26, when the SR 16/I-5 Westbound Nalley Valley Viaduct opens to motorists in Tacoma. For those driving anywhere from I-5 to anywhere from Gig Harbor and Gorst to Poulsbo and Port Townsend this is welcome news.

The new viaduct improves flows – removing a bottleneck and weave from the interchange completely – and reduces the potential for collisions for drivers. Between 2005 and 2009, an average of 26 collisions occurred at the weave annually. This number is projected to decline considerably as a result of the new construction.

This is a great thing, especially for those who not-so-fondly remember heading north on I-5 to the Bremerton exit, running into to a ridiculous wedge that attempted to cram three lanes of traffic down to a single lane, and then immediately upon entering westbound SR 16 had these same drivers trying to weave into oncoming traffic also headed westbound on SR 16 from southbound I-5. As motorists attempted to either get on mainline 16 or take the Sprague Avenue exit, what followed was a poorly choreographed ballet that featured frantic cut-offs, brake lights and applause in the form of honking horns. A mess really.

That’s all coming to an end, though. And this was definitely reason for WSDOT to honk its own horn.

About 50 people, including federal, state and city representative gathered on Sprague off-ramp Wednesday, June 22 to mark the occasion.

The $139 million viaduct was $14 million under budget and completed several months ahead of schedule. Crews built 10 new bridges – including a segmental overpass connecting northbound I-5 to westbound SR 16 – since Guy F. Atkinson Construction started the $120 million, nickel-funded project in January 2009. The bridges, constructed from new approaches on 77 piers, span more than 7 acres.
It was a massive project, but it is just the beginning in terms of coming improvements for Tacoma traffic.

The work supports construction of the Eastbound Nalley Valley Project, which begins this fall and in 2013 will move eastbound SR 16 traffic onto a new viaduct structure, and open a new ramp between S. Sprague Avenue and eastbound SR 16. In 2020-2022, WSDOT returns to SR 16/I-5 to add HOV lanes, completing the overall project and helping the agency move Washington even more safely, quickly and efficiently.

It might seem like a ways off, and it is, but for anyone who has ever witnessed the SR 16/I-5 ballet in full swing, it’ll be worth the wait.