SR 99 - NB Duwamish River Bridge - Select Grid Deck Replacement - Complete September 2020


During summer 2020, we replaced 14 steel panels, each one about 6 feet by 26 feet, on the roadway deck of the northbound SR 99 Duwamish River Bridge, commonly known as the 1st Avenue South bridge. This work keeps the bridge in a state of good repair. This highway is a critical route between cities like Burien, Normandy Park and SeaTac, and Sea-Tac Airport to Seattle, carrying about 62,000 vehicles each day.

How you benefit

Safety: This work increases traction on the bridge and provide a smoother, safer ride for travelers.

Preservation: Replacing the grid deck panels helps preserve the bridge structure. Regular maintenance is a key part of keeping highways open and available for personal and commercial traffic.

Economic: This work reduces the need for costly emergency repairs.


This $1.3 million project was paid for by pre-existing state funding sources.


Northwest Region Communications
15700 Dayton Avenue North
Seattle, WA 98133

A small map showing the location of the SR 99 Duwamish River Bridge select grid deck replacement project.