Alaskan Way Viaduct demolition

Overview of purpose and need

The Alaskan Way Viaduct was a double-deck concrete highway running along Seattle’s central waterfront. Built in the 1950s, the viaduct was damaged in the 2001 Nisqually Earthquake.

While the viaduct was strengthened and safe for daily use, the structure remained seismically vulnerable. The viaduct’s role in moving people into and through downtown Seattle was replaced by the new SR 99 tunnel and a new Alaskan Way surface street built by the City of Seattle's Waterfront Seattle Program.

How you benefit

In addition to the safety benefits of replacing an aging and seismically vulnerable structure with a modern tunnel, removing the viaduct helped transform Seattle’s central waterfront.


  • Fall 2011: Crews demolished the viaduct's southern mile south of the Seattle waterfront (Holgate to King).
  • January 11, 2019: Crews demolished a small section of the remaining structure as part of the final construction needed to open the new SR 99 tunnel.
  • February 4, 2019: The new SR 99 tunnel opened to vehicles.
  • February 12, 2019: Demolition began on the remaining viaduct structure between South Dearborn Street and Battery Street.
  • November 21, 2019: The final segment of viaduct was cut and removed.


Demolishing the Alaskan Way Viaduct is part of the Alaskan Way Viaduct Replacement Program. The contract that included this work, which also includes the Battery Street Decommissioning and North Surface Streets and funds associated with rebuilding Alaskan Way along Seattle’s waterfront, was $366.2 million dollars. Funding comes from state, federal and local sources.

Photos and videos



Map of downtown Seattle showing viaduct running along waterfront between the stadiums and the Belltown neighborhood