15th Ave NE & NE 105th St Bridge Seismic Retrofit

Updated: February, 2026

What's happening now?

Ongoing One-Lane Closures through Early March

• As crews work on retrofits to the bridge’s crossbeams and footing, they are closing lanes as needed to make space for construction equipment and materials.
• We expect that these ongoing closures will last through early March, with occasional one-lane closures and full bridge closures scheduled afterward as necessary.
• If we need to fully close the bridge, we’ll let you know ahead of time.

Here’s what you can expect in 2026: 

• Crossbeam retrofits: Crews have approximately 3 crossbeams left to retrofit. They’ll continue to place reinforcing bars, create concrete forms, and pour concrete crossbeams between the bridge columns during full closures as they make progress on these retrofits. This work will continue through spring 2026.
• Footing retrofit: Now that preliminary testing is complete, crews are installing permanent piles as part of retrofits to the bridge footing. They’ll be installing these piles through early 2026.
• Landscaping: Once crews complete retrofits to the bridge’s crossbeams and footing, they’ll landscape the area under the bridge. We expect this work will happen in spring 2026. 

Progress Update 

• Crossbeam retrofits: Work on retrofits to the bridge crossbeams continues with crews placing reinforcing bars, creating concrete forms, and pouring concrete crossbeams between the bridge columns.
  • Crossbeams are horizontal supports that connect to the vertical parts of the bridge, adding stability and strength.
  • We expect that this work will be complete as soon as spring 2026. 
• Footing retrofits: Crews are making progress on piling, which involves installing long, slender columns called piles into the ground at the base of the bridge.  
  • These retrofits to the bridge footing, which will be complete as soon as summer 2026, will enhance stability and the bridge's ability to withstand seismic events.

We expect the project to be finished in summer 2026. 

If you have questions about this project, please contact us at BridgeSeismicRetrofit@seattle.gov or (206) 775-8734. To receive project updates, sign up to join our project listserv. 

About the Project 

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, 16 bridges were selected for seismic reinforcements, including the 15th Ave NE and NE 105th St bridge. This bridge is a 480-foot-long concrete bridge designed by Homer Hadley and constructed in 1949, prior to the modernization of the seismic design code. 

Spanning a forested ravine over Thornton Creek and connecting to Northgate Way area, the 15th Ave NE and NE 105th St bridge carries both vehicular and pedestrian traffic and is supported by five concrete piers. SDOT strengthened the original concrete box girders, added new abutments, and made other improvements to the bridge in 2011. 

Here’s what we’ll do to make the bridge stronger and less vulnerable in the event of an earthquake:

• Foundation Work: We will make the base of the bridge stronger by adding extra support under the ground. We will reinforce the concrete footings and install micropile foundations, which are small, strong columns placed deep in the ground. These changes will help the bridge stay steady and safe during earthquakes.
• Column Upgrades: We will reinforce the columns at two locations to increase strength and resiliency against earthquake loads.
• Crossbeams Reinforcement: The crossbeams are the horizontal pieces that connect the columns. We will add extra support to these concrete beams to improve the stability of the bridge as a whole.

Additionally, this project includes: 

• Water Main Upgrades: 
  • We will be working on an existing water pipe that is 30 inches wide.
  • We are also adding a butterfly valve, which is a round valve that helps control or stop the flow of water through the pipe.
     

  Project Area

Schedule and Construction

Construction schedules are also subject to change and depend on factors such as weather and availability of crews and materials.  

Funding

The total project estimate is $6 million and is currently funded through the Levy to Move Seattle. Approved by voters in 2015, the 9-year, $930 million Levy to Move Seattle provides funding to improve safety for all travelers, maintain our streets and bridges, and invest in reliable, affordable travel options for a growing city.

Translation and interpretation

• If you need this information translated, please call (206) 775-8734.
• 如果您需要此信息翻譯成中文 請致電 (206) 775-8734.
• Kung kailangan mo ang impormasyon na ito na nakasalin sa Tagalog mangyari lamang na tumawag sa (206) 775-8734.
• Si necesita traducir esta información al español, llame al (206) 775-8734.
• Odeeffannoon kun akka siif (206) 775-8734.
• Nếu quý vị cần thông tin này chuyển ngữ sang tiếng Việt xin gọi (206) 775-8734.
• የዚህን መረጃ ትርጉም ከፈለጉ፣ በዚህ ስልክ ቁጥር ይደውሉ፡ (206) 775-8734.
• ናይዚ ሓበሬታ ትርጉም እንተደሊኹም፣ በዚ ቁጽሪ ስልኪ ይድውሉ፡ (206) 775-8734.
• 당신이 번역이 정보를 필요로하는 경우에, (206) 775-8734? 전화 해주십시오.