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Project Profiles

Alaskan Way Viaduct & Seawall Replacement


Seattle, Washington

Project Sponsor / Borrower

Washington State Department of Transportation (WSDOT)
King County
City of Seattle

Port of Seattle

Program Areas

Project DeliveryP3Revenue - Road Pricing Revenue


State Highway


The Alaskan Way Viaduct is an elevated section of State Highway SR 99, one of two major North-South corridors in the City of Seattle. The viaduct runs above Alaskan Way along the Elliott Bay waterfront, from the Belltown Battery Tunnel in the north to South Nevada Street in the south. In 2001, the viaduct was damaged by the Nisqually Earthquake, and although immediate repairs were made to reopen the facility, it became apparent that the viaduct was nearing the end of its useful life and needed to be replaced.

In January 2009, WSDOT, King County and the City of Seattle announced the Alaskan Way Viaduct and Seawall Replacement Program, which comprises two major projects and other related improvements.

  • First is the South end viaduct replacement, where a side-by-side roadway that will have wider lanes and meet seismic safety requirements will replace the existing viaduct section between South Holgate and South King Streets.
  • Second is the replacement of the Central Waterfront viaduct section, which runs between South King Street and the Belltown Battery Tunnel. This section will be replaced with a bored tunnel underneath downtown Seattle connecting the new SR 99 roadway south of downtown and Aurora Avenue in the north.
  • Other related improvements include repairs and enhancements of infrastructure components along the existing viaduct, specifically strengthening of viaduct columns in Pioneer Square; relocating of electric lines along the south end; decommissioning of the Battery Street Tunnel; a new Alaskan Way surface street along the Central Waterfront; and addition of traffic technology to SR 99.


Total: $3.137 billion

  • South end viaduct replacement: $351.0 million
  • Central waterfront viaduct replacement (bored tunnel) including north and south access and new north surface street connections: $2,053.2 million
  • Central waterfront viaduct removal, new Alaskan Way surface street, and decommissioning of the Battery Street Tunnel: $291.7 million
  • Environmental review, design, and ROW: $163.7 million
  • Other projects and construction mitigation: $202.9 million
  • Program management: $75.0 million

Funding Sources

Federal funds: $787.2 million

State funds: $2.054.1 billion

  • 2005 Gas Tax (Transportation Partnership Program) - $1,523.0 million
  • 2003 Gas Tax (Nickel Funding) - $326.3 million
  • Other State Funds - $4.8 million
  • Tolls - $200.0 million

Local Funds: $28.4 million

Port of Seattle: $267.7 million

Project Delivery / Contract Method


Private Partner


  • Seattle Tunnel Partners - A joint venture of Dragados USA and Tutor Perini Corp. The team also includes Frank Coluccio Construction, Mowat Construction, and HNTB Corp.

Project Advisors / Consultants

Not available



Duration / Status

  • South end viaduct replacement - Construction was completed in stages between 2009 and 2014.
  • SR 99 tunnel - Initial construction activities began in fall 2011. The tunnel boring machine began operation in July 2013 and stopped while undergoing repairs from December 2013 - December 2015. It is expected to complete operation in February 2017. Related south and north tunnel portal access projects are underway and anticipated to be complete in 2017. Project completion is scheduled for third quarter 2018.

Financial Status



  • The Alaskan Way Viaduct is a critical project included among "at risk structures" emphasized in the State Legislature's Transportation Partnership Program (2005), supported by a second increase in the state's gas tax over a period of two years.
  • The project will use $200 million in toll revenue, which will capture the synergy from other recent tolling projects in Washington State.

Related Links / Articles

WSDOT Project Webpage


Laura Newborn
Media Relations, Alaskan Way Viaduct Replacement Program
Tel: (206) 805-2871

Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000
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