15th Ave NE Bridge Seismic Retrofit
Updated: February 18, 2025
What's happening now?
We’ve suspended work on retrofits to help the 15th Ave NE/NE 105th St Bridge better withstand earthquakes until March! One of the materials crews need to continue work is taking longer than expected to arrive, so construction will be paused until it arrives.
Construction is expected to last approximately 12 months. During this time, we’ll be shifting traffic on 15th Ave NE in phases and there may be times when parts or the entire bridge will be closed. We will carefully plan alternative routes for pedestrians, cyclists, and drivers to use while the closures are in effect. See the ‘What to expect during construction’ section below to learn more about how construction will impact neighbors.
We understand that the bridge closure will inconvenience those who regularly use it, and we will do our best to minimize the impact. In the next couple of months, we will reach out to individual property owners and neighbors to discuss any specific impacts to their properties and any permissions that may be needed for access during construction. We appreciate your patience throughout this process.
To receive project updates, sign up to join our project listserv.
Project overview
Earthquakes could have a detrimental effect on Seattle's infrastructure. To address seismic risks to city infrastructure, the City of Seattle established a bridge seismic retrofit program to assess the seismic vulnerability of the City's bridges and to prioritize limited funding to reduce this transportation infrastructure vulnerability.
As part of the Levy to Move Seattle, 16 bridges were selected for seismic retrofits, including the bridge at 15th Ave NE and NE 105th St. The 15th Ave NE Bridge is a 480 feet long concrete bridge designed by Homer Hadley and constructed in 1949 using innovative techniques, but prior to the modernization of the seismic design code. Spanning a forested ravine over Thornton Creek and connecting to Northgate Way area, it 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.
The planned seismic retrofits to the 15th Ave NE Bridge build on the previous strengthening and include several modifications to seismically strengthen existing bridge piers and reduce the bridge's vulnerability to earthquakes.
What to expect during construction
Construction began in January 2025 and is expected to last approximately 12 months. We will continue to share information on our webpage and through weekly email updates. You can sign up for our project listserv to receive email updates.
We understand our phases of lane closures and potential partial or full bridge closures impact everyone who uses the bridge regularly. We are actively working to ensure our traffic control plan runs smoothly and impacts community members traveling as little as possible.
You can expect the following construction impacts:
- Three phases of temporary one-lane, two-way operation on 15th Ave NE
- Phase One: The northbound side of 15th Ave NE will be closed between NE 103rd St and NE 104th St. Flaggers will be on-site to alternate traffic, as needed.
- Phase Two: The northbound side of 15th Ave NE will be closed between NE 104th St and NE 106th St. Flaggers will be on-site to alternate traffic, as needed.
- Phase Three: The southbound side of 15th Ave NE will be closed between NE 106th St and NE 104th St. Flaggers will be on-site to alternate traffic, as needed.
- Potential partial or full bridge closures. We will notify nearby homes at least two weeks in advance and again 72 hours before the closure
- Work in the public right-of-way near your home or business
- Noise, dust, vibrations, and construction equipment staged within the project area
- Typical weekday work hours of 7 AM – 5 PM, Monday through Friday
We will maintain access to residences at all times. If at any point we need to temporarily restrict driveway access for homes adjacent to the bridge, we will communicate directly with affected residents prior to any restriction.
Project Area
Schedule and Construction
| Planning | October 2018-April 2020 |
| Design | January 2021-December 2022 |
| Potholing Work | Late November - December 2024 |
| Construction Began | January 2025 |
Construction is scheduled to last approximately 12 months. 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
The 15th Ave NE Bridge, which provides access across N 105th St, was one of 16 bridges selected for seismic retrofits as part of the Levy to Move Seattle. The planned seismic retrofits to the bridge include several modifications to strengthen existing bridge components and reduce the bridge’s vulnerability to earthquakes. Construction began in January 2025.
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.