It’s been a long journey from groundbreaking to nearly opening day! As we count down to Dec. 6, when the 1 Line will officially extend to Kent Des Moines, Star Lake, and Federal Way Downtown, we’re taking a look back at the years of progress that brought us here.
From the first columns and beams to the finishing touches on stations, these photos capture how much has changed — thanks to the dedication of crews, partners, and communities along the way.
It all started with a groundbreaking in July 2020. While a traditional in-person groundbreaking event could not take place under the COVID-19 health guidelines at the time, we invited everyone to join the virtual celebration:
Once open, the 1 Line will run from Federal Way to Northgate — with easy connections to the airport and downtown Seattle.
The extension adds nearly eight miles to our regional light rail system via mostly elevated tracks between SeaTac and Federal Way, as well as 3,200 parking spaces.
Construction began in 2020, and passed the 25 percent completion mark within one year.
There were challenges along the way. In July 2022, a small landslide in the area just south of the former Midway Landfill near South 259th Place revealed that soil conditions under this part of the new light rail path were more unstable than predicted.
This resulted in the engineering and building of Structure C: an innovative long-span bridge that's 28 feet tall and 1,100 long, consisting of two 300-foot-long spans and a 500-foot-long span between.
The year 2025 brought milestones and great news for the extension. A new bus loop opened and train testing began in March, and over the summer, we announced that the project would be able to open early!
Every beam, bridge, and station represents years of hard work by the people who built it. A huge thank-you to all the workers and contractors who poured their time, talent, and teamwork into making the 1 Line extension a reality.
You can meet some of these amazing organizations in person at the opening celebration for the new extension on Dec. 6! Stop by their booths, say hello, and learn more about the work they’re doing in our community. We’re grateful for their support in bringing this project to life and making this milestone possible.
On-Board Partners - Parsons, South County Transit Partners, a MottMac and AtkinsRealis joint venture.
Supporting Partners - HDR, RailPros, Axiom, David Evans and Associates
Platform Partners - Mass Electric, PRR, KBA