Battery Street Tunnel

Filling and sealing the Battery Street Tunnel

Why close the Battery Street Tunnel

With the Alaskan Way Viaduct closed, SR 99 no longer runs through the Battery Street Tunnel. Like the viaduct, the tunnel was built in the 1950s and is seismically vulnerable. Any new or continued use of the tunnel would require prohibitively expensive renovations. Closing the Battery Street Tunnel allows WSDOT to rebuild the three-block stretch of Seventh Avenue North at the tunnel’s north end, improving east-west mobility in that neighborhood.

View inside the Battery Street Tunnel showing the tunnel half filled to the ceiling with crushed rock

Above: The view inside the tunnel in July 2019 showing the crushed concrete fill material in place.

Scope of work

Work began on Feb. 12, 2019 and is scheduled to be complete in late 2020 or early 2021. The major elements of this work are:

  • Decommissioning and removing the tunnel’s utility and mechanical systems.
  • Removing hazardous materials from the tunnel.
  • Filling the tunnel and sealing its entrances.
  • Street restoration along Battery Street, including sidewalk improvements, new curb ramps, street lighting and other pedestrian improvements.

The blue-highlighted zone in the map below shows the work area for the project:

Map of Battery Street with blue highlighted area stretching from First Avenue to Borealis Avenue

Filling the tunnel (updated December 2019)

In May 2019, the contractor Kiewit began filling the lower half of the Battery Street Tunnel. The fill material is crushed concrete salvaged from the demolition of the viaduct. Trucks poured the crushed concrete through hoppers placed atop grates in Battery Street. Inside the tunnel, vibratory rollers spread and compacted the material in layers. 

Read more about this process:
The tunnel was filled to about seven feet from its ceiling with the crushed concrete fill. The top seven feet will be filled with a low-density cellular concrete pumped into the tunnel from the surface in 2020. See the diagram below:

Diagram showing how the lower half of the tunnel will be filled differently than the top

Effects of construction

Construction will occur both inside the Battery Street Tunnel and on the surface street above. During construction, neighbors and travelers should expect:

  • Traffic lane closures along Battery Street, with a limited number of night and weekend full closures.
  • Construction equipment staged at the south end of the tunnel on the west side of First Avenue.
  • Temporary building and parking access restrictions according to previously negotiated Temporary Construction Easements.
  • Increased truck activity on Battery Street and near the north and south portals.
  • Vibration from tunnel filling activities, plus other typical construction effects such as increased dust and noise.
  • Local sidewalk access maintained with possible short pedestrian detours.
  • Most construction during the daytime, with occasional night work.
  • Water misting to reduce dust.
  • Occasional temporary closures of cross-street traffic.
  • Temporary parking restrictions on Battery Street and side streets for equipment staging.

How to stay informed

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