SR 99 Connections

SR 99 Connections

One of the final pieces of work involved in opening the new SR 99 tunnel to drivers is connecting the tunnel to SR 99 at both ends. The SR 99 Connections Project encompasses this work. 

Street closures and night work

For the latest construction notifications, visit the Notices and detours page.

Timeline: February 2018 - early 2019 (estimated)
Contractor: Scarsella Brothers, Inc.
24-hour noise hotline: 206-510-1428
Stay informed: Email viaduct@wsdot.wa.gov to be added to the construction email list

Project overview

The contractor Scarsella Bros. constructed the ramp and road connections between the new tunnel and SR 99. Crews are currently completing the northbound off-ramp to downtown and Alaskan Way near the tunnel's south portal.

North portal work

Near the tunnel’s north end, crews conducted final work to connect SR 99/Aurora Avenue North to the tunnel. Most of this work happened during the three-week closure of SR 99 before the tunnel opened to drivers on Feb. 4, 2019. Crews also paved a block of Sixth Avenue North that was part of the tunnel construction zone, and installed traffic signals at the intersection of Aurora Avenue North and Harrison Street.

Work sequence at the tunnel's north portal (click for PDF)

Traffic routes at north portal when work is complete

South portal work

Scarsella Bros. crews built the road connections between SR 99, surface streets, and the new tunnel. The graphics below show how most of the work took place. This included creating a new stretch of South Dearborn Street.

The contractor completed the ramps to the new tunnel, working in space that was occupied by the SR 99 temporary bypass. This work was one reason why the viaduct closed for approximately three weeks before the tunnel opened to traffic on Feb. 4, 2019.

Work sequence at the tunnel's south portal (click for PDF)

Tunnel south portal showing final traffic routes