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Filling and sealing the Battery Street Tunnel in Seattle


The SR 99 tunnel in Seattle opened to drivers on 04.02.2019. The tunnel and a new Alaskan Way street are designed to work together to replace the functionality of the viaduct. The tunnel provides a direct route from Seattle's stadiums to the Space Needle. The contractor Scarsella Bros. constructed the ramp and road connections between the new tunnel and SR 99. It is the largest double-deck highway tunnel of its kind in the country and features modern safety and operations systems.

With the Alaskan Way Viaduct closed, SR 99 no longer runs through the 960 m 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 also allows WSDOT to rebuild the three-block stretch of Aurora Avenue at the tunnel’s north end, improving east-west mobility in that neighbourhood.

Work began on 12.2.2019 and will be completed in late 2020. 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 tunnel will be filled in two phases, with material brought into the tunnel both from its south entrance and through grates along Battery Street above. For further information please visit http://www.wsdot.wa.gov. Also for archive information go to https://tunnelbuilder.com/News/Final-piece-of-the-TBM-Bertha-removed-from-tunnel.aspx and https://tunnelbuilder.com/Archive/Projects.aspx?&projectcode=us%2f6914/19.