Thursday, June 21, 2018

The challenge to drivers before the SR 99 tunnel opens

Monday, Sept. 17
The three-week SR 99 closure is set to begin on Jan. 11, 2019. Learn more about the decision to stick with the previous timeline of an early 2019 tunnel opening on the Alaskan Way Viaduct Replacement Program website.
By Laura Newborn

The new SR 99 tunnel beneath downtown Seattle could open as soon as this fall, providing a direct route from CenturyLink and Safeco fields to the Space Needle. There's a lot of work that has to happen before we can give you an exact date for the tunnel opening, but one thing we can tell you is travelers will face big challenges immediately before the tunnel opens. We must close the viaduct before we can open the tunnel – there's no other way to connect SR 99 to the new tunnel. That means there will be three weeks of no SR 99 traffic through Seattle – no viaduct and no tunnel.

Why do you have to close the viaduct before the tunnel opens?
The current alignment of SR 99 near the stadiums is temporary. Today's configuration allows traffic to weave through an active construction zone. After the tunnel is complete, tested and all systems are 'go', we will have to realign SR 99 and connect the tunnel ramps.

This means we must close SR 99 from the West Seattle Bridge to the south end of the Battery Street Tunnel for approximately three weeks (if the weather cooperates). The pictures below explain why. The orange areas on the right show the areas where crews will have to work to build new ramps and road connections to open the tunnel to traffic. As you can see, these work areas sit right atop the present-day highway.
Left: Current SR 99 near the stadiums (looking south). Right: Work areas needed to open the tunnel

Left: Current tunnel portal near Seattle Center. Right: Work areas needed to open tunnel

Three weeks of a full SR 99 closure, plus additional time for ramp closures
The intensive amount of work required at the tunnel's south end near the stadiums means that key ramps will close sooner and open later than the rest of the highway. For drivers heading south, the current southbound exit to South Atlantic Street (for reaching the stadiums and interstates) will close approximately one week before the full SR 99 closure to create room for the realignment work. For your future planning, this exit will disappear entirely when the tunnel opens, replaced by a stadium/I-5/I-90 exit from the tunnel.

For drivers heading north toward downtown, the new SR 99 northbound exit ramp to Alaskan Way and downtown Seattle will open two weeks after the tunnel opens, as this ramp will take longer to complete.

If you're driving from the north during the closure, SR 99 will narrow to one lane in each direction near Mercer Street so crews can build a new section of highway connecting SR 99 to the tunnel (see picture above). The Battery Street Tunnel will remain open during the three-week closure, but drivers will have to exit and enter at the Western Avenue off and on ramps.

It's a little hard to follow. Our program website has additional graphics showing the closure step by step.

I don't use SR 99, why should I care?
We know from experience that closing SR 99 through Seattle has a region-wide impact. During past planned closures, commutes on I-5, I-405 and I-90 started earlier and lasted longer. Seattle city streets were also more crowded. Many drivers pitched in and changed their commute times, but there's no question that three weeks is a long time to ask drivers to sustain change. Add some rain to the equation and traffic could become even more challenging. We are working with our partner agencies to identify multiple ways to help keep people moving during the three-week shutdown of SR 99, but there's no doubt this will be a challenging time for everyone. We will share more information as we get closer to a starting point for the closure.

What can I do now?
We don't yet have a date for this three-week closure, but it could come as soon as this fall. We will be able to give about a month's warning. Still, thinking about potential alternatives now can help you later.
Using your tools (pdf 488 kb) and having a game plan will be vital during the closure. We will have much more information about alternative ways to keep people and goods moving as the closure approaches.