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 October 12, 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 4,212 feet 45%
Southbound west walls (lower half) 6,713 feet 72%
Southbound roadway 7,834 feet 85%
Northbound walls 8,695 feet 94%
Corbels 9,270 feet 100%
Northbound roadway N/A N/A
Launch pit 96% 96%
Disassembly pit 5% 5%
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 October 19, 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 October 19, 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 and hangers for hanging the lights and signs.

  Key MEP components* Distance completed (of 9,270 total feet) Percent completed
Hangers (NB) 6,819 feet 74%
Hangers (SB) 1,121 feet 12%
Lighting (NB) 5,532 feet 60%
Lighting (SB) 240 feet 3%
Mesh and fire proofing (NB) 6,332 feet 68%
Fire suppression (NB) 3,896 feet 42%
Mesh and fire proofing (SB) 1,121 feet 12%
Fire suppression (SB) 240 feet 3%
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.