Tracking Progress

Latest tunnel progress

Tunneling is complete, but much work remains before the SR 99 tunnel is ready for traffic. Click through the graph below for the progress of various elements of tunnel work. This information is updated monthly; progress reporting lags behind completed work.

Last updated on August 15, 2017

The interior structures are the walls and roadway decks that make up the double-deck highway within the tunnel. Also tracked here is the work to build the highway in Bertha's launch pit and disassembly pit.

    Distance completed
(of 9,270 total feet)
Percent completed
Southbound west walls (upper half) + east walls 2,271 feet 24%
Southbound west walls (lower half) 5,741 feet 62%
Southbound roadway 7,000 feet 76%
Northbound walls 7,952 feet 86%
Corbels 8,559 feet 92%
Northbound roadway N/A N/A
Launch pit 20% 20%
Disassembly pit N/A N/A
Cross section diagram of tunnel's interior structures
Map of tunnel route through downtown Seattle

Select a radio button from above to see specific component progress.

Last updated on August 10, 2017

The SR 99 tunnel will have 16 electrical rooms spaced along the tunnel alignment. These rooms contain and route the systems for powering the tunnel's lights, traffic control, cameras, and other safety and operational systems.

Installing the rooms involves pouring the concrete for the ceiling and walls, installing equipment and conduit, and connecting the rooms to each other and the tunnel's operations buildings.

Tunnel rendering cross-section showing the location of an electrical room
Map of tunnel alignment showing location and status of electrical rooms

Last updated on August 10, 2017

As the roadway decks are built, crews can install the tunnel’s mechanical, electrical, and lighting systems. These include fire protection and tunnel lighting, and the wire mesh hangers for hanging the lights and signs.

  Key MEP components* Distance completed (of 9,270 total feet) Percent completed
Hangers (NB) 5,927 feet 64%
Hangers (SB) Not yet started N/A
Lighting (NB) 4,903 feet 53%
Lighting (SB) Not yet started N/A
Mesh and fire proofing (NB) 5,589 feet 60%
Fire suppression (NB) 3,096 feet 33%
Mesh and fire proofing (SB) Not yet started N/A
Fire suppression (SB) Not yet started N/A
Cross section of tunnel showing parts of interior structures and utilidors

*This list is not exhaustive

Map showing tunnel alignment through downtown Seattle

Select a radio button from above to see specific component progress.