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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 DeliveryRevenue - 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; maintenance and repair to Battery Street Tunnel; and addition of traffic technology to SR 99.


Total: $3.144 billion

  • South end viaduct replacement: $377 million
  • Central waterfront viaduct replacement (bored tunnel): $2,034 million
  • Central waterfront viaduct removal: $290 million
  • Environmental review, design, and ROW: $164 million
  • Other projects and construction mitigation: $204 million
  • Program management: $75 million

Funding Sources

Federal funds: $702.4 million

State funds: $2.103 billion

  • 2005 Gas Tax (Transportation Partnership Program) - $1,505.7 million
  • 2003 Gas Tax (Nickel Funding) - $224.1 million
  • Other State Funds - $174 million
  • Tolling - $200 million

Local Funds: $57.2 million

Port of Seattle: $300 million

Project Delivery / Contract Method


Private Partner


Project Advisors / Consultants


  • 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.



Duration / Status

  • South end viaduct replacement - Construction began in 2010 and is scheduled for completion in 2013.
  • Central waterfront - Initial construction activities began in fall 2011. The tunnel boring machine is scheduled to begin boring in summer 2013. The tunnel will open to traffic in late 2015.

Financial Status

Federal, state, and local funding of $2.84 billion is committed. Port of Seattle's contribution of $300 million has also been secured. A tolling study commissioned by the legislature was prepared by WSDOT examining five toll scenarios and their ability to contribute up to $400 million in remaining funding and, at the same time, encourage through trips to use the tunnel, especially during peak travel times. The toll contribution was reduced to $200 million during the 2012 legislative session with federal funds making up the difference.


  • 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


KaDeena Yerkan
Manager, Communications and Public Involvement
Tel: (206) 805-2846

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