15th Ave NE Bridge Seismic Retrofit

Updated: April 29, 2024

What's happening now?

Pre-Construction project timeline graphic

We have completed the seismic retrofit design work and expect construction to begin in the Fall of 2024.

Construction is expected to take around 9 months to complete. During this time, 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. These alternate routes will be finalized closer to the start of construction, once we have selected a contractor.

We understand that the bridge closure will inconvenience those who regularly use it, and we will do our best to minimize the impact. Once we have our contractor on board, we will provide more details about the project schedule and how it will affect the area.

Here are some of the impacts we anticipate:

  • Construction work will take place in the public right-of-way near your home or business
  • There will be times when the entire bridge will be closed, and we will provide detours to safely guide pedestrians, cyclists, and drivers around the construction zone
  • There may be cccasional traffic or lane restrictions, including closures on side streets
  • Temporary parking restrictions will be enforced, and signs will be posted 72 hours in advance to notify residents not to park in the areas
  • You can expect typical construction activities such as noise, dust, parked equipment, materials, and workers in the work area
  • Construction work will generally occur weekdays between 7 AM and 5 PM, from Monday to Friday

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.

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. 

Graphic showing cross section of bridge structure and where our proposed work is located.


Project area

Project map showing project area on 15th Ave NE Bridge between NE 106th St and NE 104th St.

Schedule and construction

Planning: October 2018 - April 2020

Design: January 2021 - December 2022

Construction: Fall 2023


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.



Greg Spotts, Director
Address: 700 5th Ave, Suite 3800, Seattle, WA, 98104
Mailing Address: PO Box 34996, Seattle, WA, 98124-4996
Phone: (206) 684-7623

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The Seattle Department of Transportation (SDOT) is on a mission to deliver a transportation system that provides safe and affordable access to places and opportunities for everyone as we work to achieve our vision of Seattle as a thriving, equitable community powered by dependable transportation.