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Alaskan Way Viaduct

Recent developments

Planning continues on the bored-tunnel alternative to replace the Alaskan Way Viaduct. Under this alternative, State Route 99 would be moved into the tunnel and connected to surface streets at the ends of the tunnel, and the existing viaduct along the waterfront would be removed. The bored tunnel alternative was jointly recommended by Governor Christine Gregoire, King County Executive Ron Sims and Seattle Mayor Greg Nickels in January 2009, and approved by the Washington Legislature in May and by the Seattle City Council in October.

The Washington State Department of Transportation (WSDOT) is developing a Supplemental Draft Environmental Impact Statement for the central waterfront section of the viaduct project. This document analyzes the bored-tunnel alternative and builds upon the previous review of the other alternatives. It will be published for public review in 2010. You may submit comments via e-mail to; through the viaduct program Web site [external site]; through the program hotline (1-888-AWV-LINE), or by mail to Alaskan Way Viaduct and Seawall Replacement Program, 999 Third Ave., Suite 2424, Seattle, WA 98104.

King County and WSDOT have developed a three-pronged mitigation plan for the initial viaduct replacement construction projects. Known as “Moving Forward,” this plan will do the following:

  • Provide additional transit service to accommodate 1,212 new riders on five bus routes (21, 22, 54, 56, and 121) that serve areas where construction will have an impact.
  • Promote the use of alternative transportation in the corridor through such efforts as rideshare promotions, employer/residential outreach, and telecommuting incentives. Most programs will start in early 2010.
  • More closely monitor travel times of buses that serve areas affected by construction to assess the effectiveness of enhanced transit service and inform future proposals for additional service.

Funding for this enhanced transit service runs out in 2013. King County and the other viaduct partners are working with the Washington Legislature to find a new funding source for transit expansion.

Partnership process

The bored-tunnel alternative is the result of a combined effort by the State of Washington, King County, and the City of Seattle to find a comprehensive solution for the Alaskan Way Viaduct’s central section, between S King Street and the Battery Street Tunnel. Starting in 2007, the three agencies, with guidance from a Stakeholder Advisory Committee [external site], analyzed several replacement alternatives and evaluated them based on six guiding principles:

  • Improve public safety
  • Provide efficient movement of people and goods
  • Maintain or improve the economies of downtown Seattle, the port, the region, and the state
  • Enhance Seattle’s waterfront as a place for people
  • Create solutions that are fiscally responsible
  • Foster environmentally sound approaches

Along with the bored-tunnel alternative, the county and city envision other improvements as part of the viaduct replacement program. The city would build a new roadway (funded by the state) and new public open space along the waterfront once the viaduct is removed, improve other city streets, and replace the central waterfront seawall. The county would seek new funding sources to invest in expanded transit service. The city and county are responsible for managing these projects, including any necessary environmental review.