Bridge Seismic Program

Updated: April 17, 2025

What is the Bridge Seismic program? 

Seattle is located in an earthquake-prone region, and earthquakes can seriously impact our bridges. To address this risk, the City of Seattle created the Bridge Seismic Program to evaluate which bridges are vulnerable and reinforce them to better withstand seismic events.

As part of the Levy to Move Seattle, we’ve committed to reinforcing 16 identified vulnerable bridges.    

What is a Bridge Seismic Retrofit? 

A bridge seismic retrofit strengthens bridges to make them safer during earthquakes. The Seattle Department of Transportation (SDOT) conducts modifications to reduce the impact of earthquakes on bridges while keeping bridges operational as they are.

Common retrofit improvements include:

1. Fixing cracks and damaged concrete.
2. Installing concrete blocks and support shells around columns and crossbeams.
3. Reinforcing arches with concrete infill walls.
4. Wrapping key parts of the bridge (like columns and beams) with carbon fiber for added strength.
5. Replacing expansion joints at both ends of the bridge.  

The illustration above shows Common retrofit improvements.

Why is Seismic Retrofitting Important?  

Seattle is in an earthquake-prone region, so ensuring our bridges are resilient is crucial. Retrofitting bridges improves public safety and protects critical infrastructure in the event of an earthquake.

Where Are Seismic Retrofits Happening?

Active projects

Here are bridges currently undergoing or planned for retrofitting. Click on each to learn more about specific projects on their dedicated pages:

• 15th Ave W/NW & Ballard Bridge Paving & Safety Project
• Admiral Way North & South Bridges
• McGilvra Blvd E Bridge
• 15th Ave NE/NE 105th St Bridge

Completed Seismic Retrofit Projects

Here are bridges that have already been retrofitted:

• 13th Ave NW/Holman Rd NW Pedestrian Bridge
• N 41st St Pedestrian Bridge  
• Delridge Pedestrian Bridge  
• N 102nd St/Aurora Ave N Pedestrian Bridge  
• 8th Ave NW/NW 133rd St Bridge
• Cowen Park Bridge
• SW Andover St Pedestrian and Bicycle Bridge
• W Howe St Bridge 
• Lower Spokane St Swing Bridge Silt Removal  
• NE 45th St Pedestrian Bridge
• McGraw St Bridge

Materials

Fact Sheet (December 2023) 

Funding 

From 2016 to 2024, the Bridge Seismic Program has been funded by:

• $67 million from the Levy to Move Seattle
• $14 million in additional funding sources

Translations

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