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Monday – Friday, 8:30 am – 4:00 pm.

In-person assistance hours

Monday – Thursday, 8:30 am – 4:00 pm.

Public Works Address

6300 Southcenter Blvd. Suite 200
Tukwila, WA 98188

CONTACT US

✉️ PublicWorks@TukwilaWA.gov

☏ (206) 433-0179

Fax (206) 431-3665

42nd Ave Bridge S Replacement Project

Project Overview

Built in 1949, the 300-foot-long 42nd Avenue S Bridge in Tukwila, Washington spans the Duwamish River and serves as a critical link for both local residents and commerce across the region. Despite its vital role, the bridge no longer meets modern safety and design standards and has exceeded its intended lifespan. 

In late 2021, the bridge was struck by an over-height truck, damaging key structural elements. To protect public safety, the bridge was repaired and, based on an engineering study, temporarily restricted to one-way southbound traffic. This configuration will remain in place until the new bridge is constructed. Replacing the bridge is the most reliable way to ensure safe access for residents, businesses, and emergency services. The replacement project will: 

  • Restore a safe, reliable crossing over the Duwamish/Green River
  • Improve access for residents, businesses, freight, and emergency services 
  • Enhance environmental conditions for salmon and river habitat 
  • Honor the historic and cultural significance of the river and the existing bridge 

Large bridge projects that involve in-water work, salmon habitat, historic structures, and tribal treaty rights require extensive design, permitting, and consultation. Multiple state and federal agencies must review and approve the project before it can advance to construction.  

Targeted project completion: by the end of 2029 

The City will continue to update this project webpage as major milestones are reached. For general project questions, please contact PWTransportation@TukwilaWA.gov 

 

Project Schedule

Where we are now 

The project design is nearing completion. Although the City had initially planned to select a contractor for construction in 2026, the permitting process and final design submittal have been delayed due to ongoing tribal consultation and required environmental mitigations. Tribal concurrence is required before the City can secure necessary permits and move forward with construction. 

 

Permitting and agency review 

Once final design is complete, the project can then be formally reviewed and approved by multiple state and federal agencies, including a required decision under the National Environmental Policy Act (NEPA). Completing NEPA is required before certain federal funds can be used and before key permits can be issued. 

NEPA is a federal environmental review process that covers: 

  • Historic and cultural resource preservation 
  • Endangered species and critical habitat protection 
  • Water quality and aquatic resources 
  • Impacts to navigable waters and public access 

Under normal circumstances, this level of coordination and review from all agencies can take several years. Recent federal staffing reductions and evolving policies have created capacity constraints and backlogs at many agencies, which is slowing review timelines and is expected to delay approvals for this project.  

 

Anticipated completion 

The project is currently targeting completion by the end of 2029, but the specific date when the bridge will open to traffic is to be determined. Construction timing depends on the limited times of year when work is allowed in the water to protect fish, as well as the contractor’s construction approach. 

As these details become clearer, the City will provide updated schedule information. 

Project Funding

Grant Funding 

The project relies on a combination of federal, state, and local funds. The Governor’s proposed supplemental budget includes $5 million in 2026 and $12 million in the 2027-2029 Budget. The City is requesting that the full amount be available in the next biennium (2027-2029) when construction is anticipated to begin. The City is also working with Washington State Department of Transportation (WSDOT) to increase the federal Local Bridge Program grant from $12 million to $25 million. 

City staff are coordinating with the City’s state and federal lobbyists to monitor funding availability as we get closer to construction.  

 

Funding Summary  

Project Cost  Dollars (in millions) 
Design (PE) Phase  $3.80 
Construction (CN) Phase  $42.0 
Total   $45.8  

 

Funding Source  Dollars (in millions) 
Local Sources  $0.90 
State Sources  $17.0 
Federal Sources  $26.5 
Remaining Gap  $1.4 
Total  $45.8 

Overall funding strategy 

Even with state and federal support, the City continues to: 

  • Pursue additional grant opportunities to close remaining funding gap 
  • Coordinate with regional partners such as WSDOT and Puget Sound Regional Council 
  • Align funding timelines with the updated design, permitting, and construction schedule 

Project Library