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The Cowen Park Bridge seismic retrofits are complete!

We recently completed seismic retrofit construction on Cowen Park Bridge.

Infrastructure maintenance is critical for a healthy, vibrant, and connected city. Earthquakes could have a significant detrimental effect on Seattle’s infrastructure. That’s why in 2016 the City of Seattle established a bridge seismic retrofit program and selected 16 bridges for seismic retrofits, all funded and made possible by the voter approved Levy to Move Seattle.

Seattle, being the fastest growing large city of the previous decade, requires a significant level of infrastructure investment that’s only possible because of this critical Levy. 

The bridges chosen for the seismic retrofit program were some of the most seismically vulnerable structures throughout the city.

The West Seattle High-Rise Bridge was not added to the program because it was designed in the late 70s/early 80s when seismic design requirements were far more robust than those for bridges designed in the preceding decades. Additionally, there was no reason for us to think that the West Seattle High-Rise Bridge was in urgent need of repair until very, very recently when cracks suddenly began growing by as much as 4.5 feet in two weeks. 

A map showing the Cowen Park Bridge seismic retrofit.

Cowen Park Bridge is the first completed project of the bridge seismic retrofit program.

The bridge connects the Roosevelt and Ravenna neighborhoods with the University District via 15th Ave NE. It crosses a deep ravine in Cowen Park, which is just west of Ravenna Park. 

Cowen Park Bridge was built in 1936, prior to the modernization of the seismic design code.

Notable for its art deco style, the bridge is listed in the National Register of Historic Places and is a designated City landmark. The completed seismic improvements will strengthen Cowen Park Bridge’s resiliency to seismic events like earthquakes.

Underside of the Cowen Park Bridge showing installation of the carbon fiber wrapping on the arch support struts.
Underside of the Cowen Park Bridge showing installation of the carbon fiber wrapping on the arch support struts.

Construction began in November 2019, and over the last 6 months, we:

  • Strengthened the bridge’s crossbeams, columns, and arches, and arch support struts using carbon fiber wrapping
  • Installed concrete blocks and supportive shells for the bride’s columns and crossbeams
  • Strengthened the existing arch with a concrete infill wall
  • Repaired cracks in the bridge’s concrete
  • Replaced the expansion joints at either end of the bridge to stabilize movement
Crossing the Cowen Park Bridge facing north on 15th Ave NE
Crossing the Cowen Park Bridge facing north on 15th Ave NE

Safety improvements were also made for people walking, biking, or driving across the bridge.

In addition to structural repairs, we also repaved and made improvements to the bridge’s roadway, including adding protected bike lanes to separate bikes from vehicles. In a few months we’ll break ground on the 15th Ave NE Paving project which will extend bike lanes north and south of the bridge and add additional safety features including flashing lights at crosswalks and left turn pockets.

Cowen Park Bridge is one of the many bridge safety projects funded by a variety of sources, including the Levy to Move Seattle:

  • There are 16 bridge seismic retrofit projects funded by the Levy to Move Seattle, including the Cowen Park Bridge and the W Howe St Bridge in Magnolia