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Airport Way S Viaduct Closed Monday for Year-long Construction


The Airport Way South Viaduct was built in 1928 to provide grade separation between Airport Way South and the Union Pacific, Northern Pacific and Seattle to Tacoma Interurban railroad tracks. The structure, which was built and financed by the railroad companies, was later transferred to the city. Airport Way South is a heavily traveled arterial, important to businesses, freight operations, the Port of Seattle, commuters, cyclist, and residents of Georgetown and the surrounding area. With over 13,000 vehicles traveling on Airport Way South daily, the viaduct has experienced increased stress over time.

With funding from the city’s Bridging the Gap program, SDOT will replace the north and south timber-framed approach structures with a mechanically stabilized earth (MSE) wall structure. Ground improvements will address poor soil conditions at the approaches. Rehabilitation and seismic improvements will be made to the main span of the viaduct. The main span of the bridge will get a new driving surface. Prior to the start of construction, improvements were made to the following surrounding Georgetown Streets: S Lucile Street, S Dawson Street, Denver Avenue S and Airport Way S.

View of old timber supports that will be replaced.

In addition to the construction, upon completion of the project, the structure will have new light poles, pedestrian railing, and a wall designed with the historical character of the neighborhood in mind.

The estimated total project cost of the project is $34 million. Completing this project is necessary to maintain a safe and reliable transportation corridor for vehicles, pedestrians, and bicycles.  Not only does it improve safety by creating a stronger, more durable structure to serve current and future traffic conditions, but it keeps freight moving with a stronger structure that improves the load-carrying capacity of this vital link. A more durable concrete deck and approaches will significantly reduce the frequency of major repairs and associated traffic disruptions. The project also serves to protect an important city asset by extending the structure’s useful life by decades.

During construction the viaduct will be closed for approximately 12 – 14 month and all vehicles and pedestrians will be detoured to Fourth Avenue S.   Bicycles will be detoured to First Avenue S.  Signage will be placed throughout the region to alert users of the viaduct closure and detour route.

Detour Details:

  • Southbound vehicles &, and pedestrians will be detoured at South Industrial Way to 4th Avenue South, returning to Airport Way South via South Lucile Street. Southbound cyclists should access 1st Avenue via Lander Street.
  • Northbound traffic will be detoured at South Lucile Street to 4th Avenue South, returning to Airport Way South via South Industrial Way.
  • Denver Avenue South and South Dawson Street between South Lucile Street and 4th Avenue South will be used primarily as a northbound truck detour route.
  • Signage will be placed throughout the region to alert users of the viaduct closure and detour routes.