Project overview
After SR 99 in Seattle was aligned to run through the SR 99 tunnel, the Battery Street Tunnel was decommissioned and filled and the tunnel's northern approach built into a new arterial street (Seventh Avenue North) featuring bus lanes and reconnected intersections.
What to expect
Final construction for this project ended in fall 2021. The south portal of the old Battery Street Tunnel was handed over to the City of Seattle, which is responsible for decisions about the future use of that land.
The northern approach to the Battery Street Tunnel was a trench that prevented east-west connections on John, Thomas and Harrison Streets. Filling the Battery Street Tunnel allowed these streets to be reconnected.
When the Alaskan Way Viaduct closed, SR 99 no longer ran through the Battery Street Tunnel. As part of the Alaskan Way Viaduct Replacement Program, the Battery Street Tunnel was decommissioned and filled. Filling and sealing the tunnel also provided an opportunity to rebuild and reconnect three streets in South Lake Union – Thomas, John and Harrison – previously cut off by SR 99.
Like the viaduct, the Battery Street Tunnel was built in the 1950s and was seismically vulnerable. Any new or continued use of the tunnel would have required prohibitively expensive renovations. Crushed concrete produced from the viaduct’s demolition was used to fill much of the Battery Street Tunnel, which kept the material out of a landfill. The rest of the tunnel was filled with several types of concrete.
The old northern approach to the Battery Street Tunnel was rebuilt as Seventh Avenue North, an arterial with wider sidewalks, two travel lanes in each direction, transit lanes to help buses get to and from SR 99, and new signalized intersections at John and Thomas streets.