Share this story...
seattle tunnel toll, SR 99
Latest News

SR 99 tunnel is built. Why can’t we use it yet?

A graphic depicting the north end of the tunnel once completed. (WSDOT)

Primary construction for the SR 99 tunnel has finally finished, with the project reaching what the Washington Department of Transportation calls “substantial completion.”

The substantial completion phase is an important distinction for the project, marking the point at which Seattle Tunnel Partners (STP) can officially hand the facility over to the Washington State Department of Transportation. The lanes are built, ventilation is working, and crews have even practiced responding to emergency scenarios inside the tunnel. WSDOT noted in a press release that “the tunnel could be technically operated as designed.”

So, what’s the hold up, and why can’t we start using the tunnel now?

There are a pair of additional milestones WSDOT much reach before the new SR 99 tunnel is officially ready. In short, crews have to build the roads that actually go into the tunnel. While the tunnel works, there’s currently no pathway for cars to drive into it. Or as WSDOT puts it:

What comes next is a variety of wrap-up work elements that, once completed, will result in the tunnel reaching the second milestone, known as ‘physical completion.’ Meanwhile, as STP works toward physical completion, WSDOT will continue to train maintenance and operations staff to ensure the tunnel and those responsible for its operation are ready to go in early 2019.

If you thought substantial and physical completion was exciting, just wait. Because after all that comes “final completion.” That’s achieved when the last bit of paperwork and documentation is finished and submitted — so perhaps not as exciting.

That said, the tunnel will actually open before final completion.

The tunnel will officially open in early 2019. Before that happens, there will be a three-week closure of SR 99 through downtown Seattle to realign the highway. Both the viaduct and the tunnel will be closed during this period. Additional ramp closures could mean up to six weeks of traffic disruption.

RELATED: How traffic will work after Seattle’s SR 99 tunnel opens

Most Popular