A 4.3-mile extension of Sound Transit's light rail network in Seattle opens Oct. 2, pushing the service farther north with the help of two underground stations and 3.5 miles of tunneling.
As Sound Transit continues its ambitious extension of light rail throughout the Puget Sound, continually pushing north, south and east, the opening of the Northgate Link Extension wraps up roughly nine years of construction on the $1.9 billion project that included twin bored tunnels under the University of Washington campus and three new stations, two underground.
The prime contractors on the project included JCM Northlink, a joint venture of Jay Dee Contractors, Frank Collucio Construction Company and Michaels Corporation, along with Hoffman Construction building the new underground U District and Roosevelt stations, Absher Construction handling the above-ground Northgate Station, Stacy and Witbeck tackling trackwork and Mass. Electric Construction Company installing systems.
Construction started in 2012, and the two-year tunneling project—from 2014 into 2016—opened up 3.5 miles of track and allowed for the new U District station located in the University District's main shopping area just north of the University of Washington campus and Roosevelt Station.
The guideway construction finished in 2018 and rail installation wrapped up in 2019. All three new stations were substantially complete at the beginning of 2021 and testing and system work has been ongoing since January.
With the opening days away, Sound Transit has run simulated services. "The sight of trains running at regular intervals is a reminder of just how close we are to the opening of the Northgate Link extension," says Peter Rogoff, Sound Transit CEO.
With the 4,784-ft-long twin tunnels running under major portions of the University of Washington campus from between 70 to 140 ft in depth, track technology includes floating slabs to help protect the school's buildings—and sensitive research work—from the vibrations of the trains. The floating concrete slabs feature natural rubber-based support pads.
The two tunnels include 23 cross passages mined by hand.
The opening of Northgate Link marks the start of major expansion for light rail over the next three years. The light rail system will go from 22 miles to 62 by 2024 as Sound Transit opens an extension to the east through Bellevue and Overlake in 2023 and south to Federal Way and north to Lynnwood in 2024. Over the next two decades, Sound Transit plans to extend the system 116 miles.
"We are building a more connected city," says Jenny Durkan, Seattle mayor.
The next project slated for opening is the Hilltop Tacoma Link Extension in 2022, which will more than double the length of Tacoma Link with an additional 2.4 miles and bringing light rail to the Stadium and Hilltop neighborhoods via six new stations.
In 2023, a new 14-mile East Link Extension opens with 10 new stations reaching Mercer Island, Bellevue and Microsoft headquarters. The following year will include extensions to the Marymoor Park area and downtown Redmond.
Southern extensions to Kent, Des Moines and Federal Way will open in 2024 with three new stations servicing 7.8 miles of fresh track.
And Northgate isn't the final stop on Sound Transit's route to the north, with a Lynnwood Link Extension pushing Sound Transit farther north when it adds 8.4 miles and four new stations in 2024.
Along with the new track on Oct. 2, Sound Transit also debuts major changes in line names. Starting in October, Link light rail becomes the 1 Line and Tacoma Link becomes the T Line. The commuter rail lines of Sounder South and Sounder North become the S and N lines. When East Link light rail opens in 2023, it will operate as a new 2 Line.