Project Title & Location

SR 99 - Alaskan Way Viaduct and Seawall Replacement Project

Project Description
The existing seismically vulnerable Alaskan Way Viaduct and Seawall are both at the end of their useful life and at risk of sudden and catastrophic failure in an earthquake. The cost to replace in-kind this seismically vulnerable structure is between $2.0 and $2.4 billion. (This figure does not include the cost of replacing the seawall or work north of Battery Street tunnel. Necessary to protect public safety and maintain the transportation corridor.

Contractor/Consultant
Parsons Brinckerhoff Quade & Douglas is the prime design consultant. Hatch Mott MacDonald is the Program Management Assistant Consultant

Recent Progress
The waterfront tunnel TS&L studies were completed to the 90% level.  No further work will continue in the central section until the WSDOT and City of Seattle come to an agreement on the design.  Utilities mapping along Western Avenue to support electrical relocation work has been completed.   Work continues on the Construction Traffic Management Plan. 

Design Construction Impacts

Utilities construction is currently scheduled to begin Summer-2008, which will impact traffic on local city streets. Roadway construction is planned to begin Winter-2009. Ramp and lane closures on SR 99 are likely to begin mid to late 2010.

Environmental Impacts / Compliance

Permits were obtained for the BST electrical upgrade work. The cultural resources research design was sent out to SHPO and the tribes moving the Section 106 compliance forward. Work has begun on developing a mitigation strategy for the final EIS.

Impacts to Traffic

The team continues to analyze the trade offs between construction duration, cost, and maintenance of traffic, and impact to the community.

Planned vs. Actual Expenditures
(Total Project Cost)

Nickel funds included in above costs

2005 Transportation Partnership Account