VIADUCT/TUNNEL TRANSITION: What you need to know about other new ramps and intersections that ARE now open

We can’t say this enough: When the Highway 99 tunnel opens – hours from now – there will be a transitional week or so during which the exit to NB 99 from the EB West Seattle Bridge is a “tunnel only” exit, because the offramp to downtown, before the tunnel, isn’t done yet. Separate from that, some new ramps/intersections HAVE just opened on both ends of the tunnel, including the one that you will use to get to SB 99 just south of the tunnel. WSDOT has just published this update that we’re reposting in its entirety:

The Feb. 4 opening of the SR 99 tunnel brings big changes to several important intersections at the tunnel’s north and south ends. New intersections can be confusing, so use the renderings below to help familiarize yourself with what you will encounter on the road. You can also preview the intersections via narrated videos.

North end of the tunnel: Harrison Street and Aurora Ave North

What’s changing:

New northbound SR 99 on-ramp
New southbound SR 99 off-ramp
Harrison Street open east-west across Aurora Avenue North
The new tunnel dives underground at Harrison Street, several blocks north of where the now-closed Battery Street Tunnel begins. The new intersection of Harrison Street and Aurora Avenue North is where the northbound on-ramp begins, and the southbound off-ramp ends. Harrison Street is now also open east-west across Aurora Avenue North.

Note: Construction begins this month on the inside lanes of Aurora Avenue North between Denny Way and Harrison Street (yellow zone at bottom). Learn more about how the North Surface Streets project is rebuilding Aurora Avenue North.

North end of the tunnel: Republican Street and Dexter Avenue North

What’s changing

New northbound SR 99 off-ramp
The intersection of Republican Street and Dexter Avenue North is where the northbound SR 99 off-ramp ends. New signals will control traffic coming off the highway. From the off-ramp drivers will be able to turn left toward Mercer Street, head straight toward South Lake Union, or turn right to head toward Denny Way. Stay alert for people using the Dexter Avenue bike lanes on both sides of the street.

South end of the tunnel: Alaskan Way, South Dearborn Street, and First Avenue South

What’s changing:

New southbound SR 99 on-ramp
New northbound SR 99 off-ramp [NOT YET OPEN]
New east-west street, South Dearborn Street
New primary path between First Avenue South and Alaskan Way
Alaskan Way extended farther south
One of the biggest changes to surface streets is at the tunnel’s south end, just west of CenturyLink field. Alaskan Way no longer ends with a jog under the viaduct onto Railroad Way South. Instead, it continues straight to a new intersection with a new road, South Dearborn Street.

South Dearborn Street is the new east-west connection between Alaskan Way and First Avenue South. This intersection connects SR 99, Alaskan Way and First Avenue. Alaskan Way continues south from this intersection toward East Marginal Way South. Railroad Way South is currently closed from First Avenue South, and when it reopens it will be a local-access-only road.

IMPORTANT NOTE: The northbound SR 99 off-ramp bridge is still under construction and will open one to two weeks after the tunnel opens.

Note: The rendering above does not show the now-closed Alaskan Way Viaduct, which sits in the yellow-highlighted work zone and will be removed section by section over the next six months.

South end of the tunnel: South Royal Brougham Way and First Avenue South

What’s changing:

New northbound SR 99 on-ramp
New southbound SR 99 off-ramp
Colorado Avenue South with two-way traffic to South Atlantic Street
Drivers who previously joined SR 99 northbound from Royal Brougham Way will find striking changes to that intersection. Where once there was a ramp to the viaduct, now there are two ramps to the tunnel. This is where southbound drivers in the tunnel will exit to reach SODO, the stadiums, and I-90 and I-5. This is also where drivers coming from I-90 or the stadiums will enter the tunnel for northbound SR 99.

Note: A shared-use path along Colorado Avenue South will be built in a future phase of the project.

South end of the tunnel: South Atlantic Street and Colorado Avenue South

What’s changing:

New surface-street connection to Alaskan Way South
Colorado Avenue South with two-way traffic to Royal Brougham Way South
The changes around South Atlantic Street are less drastic but still worth knowing. The Atlantic Street overpass over SR 99 is now a complete connection to Alaskan Way (to the north) and East Marginal Way South (to the south). You can now reach both via South Atlantic Street by taking the ramp labeled below.

Colorado Avenue South (previously called East Frontage Road) is now a two-way street, providing a north and south route between South Atlantic Street and SR 99 on- and off-ramps. A common path from SR 99 southbound to reach I-90 will be to take Colorado Avenue south, then take a left turn onto South Atlantic Street.

Note: At tunnel opening South Atlantic Street does not pass beneath the SR 99 overpass to Alaskan Way South. That connection will open later in winter/spring 2019.

Again, no specific time yet for the actual tunnel opening – but WSDOT has said it’ll be in time for the earliest edge of tomorrow’s morning commute (4 am-ish). We’ll have a separate update when it’s announced, and we also still have one more report in the works from Saturday’s tunnel dedication.

17 Replies to "VIADUCT/TUNNEL TRANSITION: What you need to know about other new ramps and intersections that ARE now open"

  • shipwrecked_and_comatose February 3, 2019 (3:41 pm)

    Did they hint at a timeline for turning the bus-only lane eastbound on the bridge to the 4th ave S exit back into a normal lane?  The loss of this lane is crippling car traffic eastbound on the bridge during the am commute. Our nightmare in West Seattle won’t end until this lane opens back up (along with the exit to 99 N from the eastbound bridge, of course.)

    • WSB February 3, 2019 (3:46 pm)

      Yes, we’ve reported that a couple times. When the new NB 99 exit opens in a week or so.

  • ScottAmick February 3, 2019 (4:57 pm)

    I can see the new traffic signals are working at the Dearborn/Alaskan Way intersection at the “Tunnel Connections South” webcam here:

  • Scott February 3, 2019 (5:02 pm)

    Good God!  The more you report and hand hold drivers the more moronic you make this sound.  We get it.  There will be new things to look out for.

    • ACG February 3, 2019 (5:52 pm)

      Chillax, Scott!  If you’ve got your bearings for navigating things, good for you and carry on. You didn’t need to waste your time reading the article or responding to it.  

  • Diane February 3, 2019 (5:56 pm)

    THANK YOU for all the details and maps; very helpful

    • WGA February 3, 2019 (6:16 pm)

      I second that!! Thanks!!

  • SSD February 3, 2019 (6:46 pm)

    Thanks for the updates!

  • JTK February 3, 2019 (8:53 pm)

    This is some of the most confusing information I have ever seen or read.  It’s like trying to find your way around all the streets under the WS bridge.   A bus ride or two will hopefully give me the time to look around and understand. Good luck out there everyone. The last three weeks have actually been decent to drive in.  I went from west Seattle to harborview area 3 times last week and I left late and got there faster even with more traffic.   

    • prayforrain February 4, 2019 (10:01 am)

      Glad it’s not just me.  That info is pretty confusing.  I’m just going to figure it out the first time I have to drive it.  

  • Dave Feinberg February 3, 2019 (9:52 pm)

    The renderings you passed along are great; providing a good visual of what to expect in coming weeks.  Thanks.

  • Raphael C McBain February 3, 2019 (10:53 pm)

    Instead of reporting the myriad details of off ramps and on ramps, just tell us West Seattle drivers when we will first be able to navigate the West Seattle bridge east bound and take the 99 exit to navigate on 99 northbound to north Seattle ( past downtown toward Fremont and more).

  • Jim Clark February 3, 2019 (11:21 pm)

    How is someone going to get to Ballard now?

    • WSB February 3, 2019 (11:41 pm)

      Probably a few options but if I had to do it tomorrow, I’d take 99 to the Green Lake exit and head west on 46th to Market. When we had to go to Ballard a few times a week for a while a few years back, I found that easier (seemed like fewer lights) than getting off the Viaduct at Western and heading for Elliott.

      • EJ February 4, 2019 (8:07 am)

        I used to live in Ballard, and had to do a bunch of trips back and forth when moving to WS. The route WSB gave is a good one (hits market st), as well as the fremont exit to 39th (hits leary ave).

    • Diane February 4, 2019 (12:12 am)

      yes, or take 99 to Queen Anne exit at Canlis, up and over, down to 15th, which will be my route to Magnolia until ramps open

    • LarryB February 4, 2019 (7:56 am)

      If I wanted to get to Ballard now, I would take 99 and get off at the first exit when you cross the Aurora bridge. Then turn left and continue along Fremont Way and Northeast 39th into Leary Way where you make a right and just follow that around until you get to Market Street. That’s the flattest route I can think of.

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