Construction of the Terminal 5 Quiet Zone has begun. SDOT’s project page has a list of what to expect during construction:

• Maintained access to businesses
• Temporary lane closures on West Marginal Way SW 
• Detours in place for people walking, biking, riding foot scooters, and driving to travel safely around work zones
• Temporary on-street parking restrictions, with "no park" signs placed 72 hours in advance
• Flaggers directing people driving, walking, and bicycling through detours around the work
• Typical construction equipment, materials, noise, workers, dust, vibrations and activity in the area during work hours
• Typical weekday work hours are 7 AM - 5 PM, Monday through Friday
• Weekend and night work as needed

Construction is anticipated to continue through Summer 2024.

This is a long-awaited development.  In my first year as a Councilmember, in 2016, I sent a letter to the Port advocating for a quiet zone. The letter said “I want to encourage your efforts to look into applying a quiet zone. Many constituents have written about the noise that is emitted from trains entering and leaving T5 at the Chelan Café intersection and have suggested making the area a quiet zone.”

This led to the development of a Statement of Legislative Intent (SLI) in 2016, SLI 66-1-A-1, in 2016, requested SDOT work with the Port of Seattle, the Federal Railway Administration, and the railway companies doing business at T-5, to extend the quiet zone along W Marginal Way between Delridge Way SW and 17th Ave SW.  In addition, the obligation to install a quiet zone was included in the Seattle Department of Construction and Inspection’s permitting requirements for the Terminal 5 expansion.

In 2021 the Council approved Council Bill 120138, authorizing the Seattle Department of Transportation (SDOT) to acquire property needed to construct the necessary improvements for a quiet zone.

See here for more about quiet zones. You can sign up for updates at SDOT’s Terminal 5 Quiet Zone page.