Spokane Street Viaduct Widening Project: Project History

SDOT conceptually designed the South Spokane Street Viaduct Widening Project in 1995 and has been implementing it in phases due to funding availability:

Seismic Retrofit (1998-1999)

Addressing safety issues first, 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

Median Barrier Installation (1999)

Continuing to address safety issues, SDOT next installed 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

Lower Roadway Utility Relocations (2003)

In 2003, SDOT relocated utilities at the street level to make room for the viaduct widening itself. The project included drainage, water and sewer lines, Seattle City Light electrical utilities, and improvements to the City's traffic signal system.

Upper roadway widening, lower roadway improvements and ramp construction (2009 - 2012)

Working for SDOT, Mid Mountain Construction built the new off-ramp from the eastbound Spokane Street Viaduct to 4th Avenue South, and made improvements to the lower eastbound Spokane Street roadway.

Working for SDOT, PCL Construction Services, Inc., is rebuilding the westbound lower Spokane Street roadway, widening the Viaduct, and building a new on- and off- ramp from westbound Spokane Street Viaduct to 1st Avenue South.