3 Line (Sound Transit)
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The 3 Line (colored magenta) is a future light rail line in the Seattle metropolitan area in the U.S. state of Washington, to be part of Sound Transit's Link light rail system. It is planned to connect Everett and Snohomish County to Downtown Seattle and West Seattle. The 3 Line would share tracks with the 2 Line from southern Everett to International District/Chinatown station along the 1 Line corridor.
The line is planned to reuse existing tracks that are part of the 1 Line and its future expansions; the 1 Line will then be rerouted through a new Downtown Seattle tunnel to be built for the Ballard Link Extension. The 16.3-mile (26.2 km) Everett Link Extension to the north of Lynnwood will have six stations and is scheduled to open between 2037 and 2041. The 4.7-mile-long (7.6 km) West Seattle Link Extension will include three new stations southwest of SODO station and is scheduled to open in 2032. The 3 Line was created as part of the Sound Transit 3 program, approved by voters in 2016, which included both projects.
The West Seattle Link Extension would include a high bridge crossing the Duwamish River adjacent to the existing West Seattle Bridge. In 2024, Sound Transit and HNTB proposed a cable-stayed bridge design that would be 1,690 feet (520 m) long and have two towers that are 374 feet (114 m) tall. The western end of the line would be tunneled between Alaska Junction and Avalon stations, where trains would begin to use an elevated guideway. The Federal Transit Administration issued their preliminary approval for the project via a record of decision in April 2025. The project is expected to cost $6.7 to $7.1 billion to construct and carry 26,000 daily passengers.
The Everett Link Extension includes a new operations and maintenance facility that is scheduled to open in 2034 at one of three sites near Paine Field and the Boeing Everett Factory. The project is estimated to cost between $5.05 billion and $6.9 billion and open either as a single phase in 2037 with its funding shortfall addressed or in two phases from 2037 to 2041.
Stations
Names and locations for future stations are provisional.
| Station | City | Location | Planned opening | Type | Connections and notes |
|---|---|---|---|---|---|
| Everett Link Extension (Everett Station to Lynnwood City Center) | |||||
| Everett Station | Everett | 3201 Smith Avenue | 2041 | Elevated | Transfer to Sounder commuter rail, Amtrak, Swift Bus Rapid Transit |
| SR 526/Evergreen | Everett | State Route 526 at Evergreen Way | 2041 | Elevated | |
| SW Everett Industrial Center | Everett | State Route 526 at Airport Road | 2037 | Elevated | |
| SR 99/Airport Road | Everett | Airport Road at State Route 99 | TBD | Elevated | Provisional station |
| Mariner | Everett | 4th Avenue West at 128th Street Southeast | 2037 | Elevated | 2 Line terminus |
| Ash Way | Lynnwood | Interstate 5 at 164th Street Southwest | 2037 | Elevated | |
| West Alderwood | Lynnwood | Vicinity of Alderwood Mall | 2037 | Elevated | |
| West Seattle Link Extension (SODO to Alaska Junction) | |||||
| Delridge | Seattle | Delridge Way Southwest near Southwest Genesee Street | 2032 | Elevated | |
| Avalon | Seattle | Southwest Avalon Way near 35th Avenue Southwest | 2032 | Retained cut | |
| Alaska Junction | Seattle | Southwest Alaska Street near California Avenue Southwest | 2032 | Underground |