Seattle Tunnel Gains Stripes, Moves Closer to Likely Fall Opening

As August nears a close, the stripes in the new State Route 99 tunnel in Seattle signify the near-completion of the multi-year construction project.

The Washington State Dept. of Transportation will make an announcement one month before WDOT closes the Alaskan Way Viaduct to traffic. Crews will then spend three weeks realigning State Route 99 into the new tunnel. The closure announcement may come soon as tunnel systems remain in testing and crews under the direction of tunnel contractor Seattle Tunnel Partners stripe the roadway markings inside the tunnel.

The striping in the tunnel between Seattle’s stadium district and the Space Needle, a roughly 2-mile-long tunnel with a 1.7-mile bored section, dug by Bertha, is wrapping up, creating 11-ft lanes and an 8-ft shoulder on the left side with a 2-ft buffer on the right on each of the tunnel’s two roadway decks.

At the same time, crews used stencils to paint “running man” symbols on walls in both directions of the tunnel. The green icons were spaced about 50 ft apart on the west walls of the southbound (upper) and northbound (lower) roadways. The stencils direct people to the nearest exits, complete with distances to those exits.

As Seattle Tunnel Partners places the finishing cosmetic touches on the interior of the tunnel, crews continue to test the operating systems within the tunnel, the final major project before Seattle Tunnel Partners can turn over the project to commissioning. There is no exact timetable on the completion of testing, although Seattle Tunnel Partners has previously said the tunnel should be ready to go by fall.

Crews working for Kiewit Infrastructure West Co. have already started on the project to realign SR99 with installation of traffic signals, striping and roadway signage that will switch traffic on Alaskan Way from beneath the viaduct to just west of the viaduct. Alaskan Way’s travel lanes were detoured beneath the viaduct years ago to accommodate construction of the seawall project and the tunnel. Crews will work to restore street traffic to the west side of the viaduct, also providing space under and around the structure for the removal work once the tunnel opens to traffic.

Follow Tim Newcomb on Twitter at @tdnewcomb.