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Spokane Street Viaduct Widening Project
Revised November 8, 2006
Click here to view a larger version of the Project Overview (PDF)
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Project Update
Contract 4, in addition to the original scope, a new eastbound 4th Avenue South loop ramp that will touch down on 4th Avenue south of Spokane Street has been added to the project. It is anticipated that the design of the widened structure and ramp will be completed by the end of the 2007. The current plan calls for construction to begin in 2008, but due to funding uncertainties, construction is likely to occur in two or three phases.
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Background:
The Seattle Department of Transportation (SDOT) began the design for widening of the South Spokane Street Viaduct in 1994. The goal is to improve traffic safety and upgrade the structural and seismic performance of the 60-year-old viaduct that connects I-5 to the West Seattle High Level Bridge. The project facilitates the movement of freight and goods in the corridor by widening the existing traffic lanes, creating a weave lane to assist westbound merging vehicular movements, and improving the surface streets adjacent to the project.
Aerial view of existing Spokane Street Viaduct
 
Existing viaduct from the surface
The basic design for the widening project was completed in 1995. Due to funding limitations, SDOT decided to implement the project in phases identified under separate contracts.
Contract 1, Siesmic Retrofit (1998-1999)
Contract 2, Median Barrier Installation (1999)
Contract 3, Lower Roadway Utility Relocations (2001-2003)
Contract 4, Viaduct Widening and Ramp Construction
(2007 - 2010)
Contract 1, Seismic Retrofit (1998-1999)
Under Contract 1 the viaduct was seismically retrofitted to improve the viaduct's ability to withstand an earthquake.
 
Photos taken after the retrofit, showing reinforced column bases and steel jackets
Contract 2, Median Barrier Installation (1999)
Still addressing safety issues first, SDOT next implemented Contract 2, installing a median barrier down the center of the viaduct. The barrier divides the two directions of traffic and all but eliminates the possibility of head-on collisions.
Median barrier
Contract 3, Lower Roadway Utility Relocations (2003)
In July, 2003, SDOT completed Contract 3, which involved the relocation of utilities at the street level to make room for the viaduct widening in Contract 4. The project included drainage, water and sewer lines, Seattle City Light electrical utilities, and improvements to the City's traffic signal system. This contract is being followed by City Light work to remove the existing utility poles and relocate electrical services underground into duct work installed under contract 3.
More information to come:
As the project progresses, more details will be made available. For questions or comments you may call Stuart Goldsmith, Project Manager, at 206-615-0860, or by e-mail.
E-mail Notification List
Spokane Viaduct Widening
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