Sound Transit contractors JCM Northlink LLC, a joint venture of Jay Dee Contractors, Frank Coluccio Construction Company, and Michels Corporation, have completed mining the last tunnel segment for the Northgate Link Extension twin tunnels. The $1.9 billion Northgate Link project will extend light rail 4.3 miles north from the University of Washington to a station next to Northgate Mall.
Their tunnel boring machine holed through the wall of a retrieval shaft at the University of Washington Station, completing the last of six tunnel segments mined by JCM Northlink LLC. Since the work began in 2014, two tunnel boring machines weighing 600 tons each excavated more than 500,000 cubic yards of soil and installed 7,352 concrete tunnel liner rings.
JCM is now digging 23 cross passages between tunnels that will serve as emergency evacuation routes and contain controls for electrical and mechanical systems, with the work expected to be complete in 2018. Future work within the tunnel will include installation of track beds, rails and communications systems.
“In just a few years, light rail riders will be enjoying fast, frequent, congestion-free service to the U-District, Roosevelt and Northgate,” said Sound Transit Board Chair and King County Executive Dow Constantine.
“By this time next month, we’ll have opened the Angle Lake station in SeaTac, our third new station in six months. These are just two examples of Sound Transit’s steady progress as we work to expand light rail throughout the Central Puget Sound region,” he added.
Construction of the three stations for Northgate Link will begin soon, with work on the Northgate Station starting this fall. Construction of underground stations in the Roosevelt and U District neighborhoods will start next year.
In 2021, when light rail service on the Northgate Link extension begins, trains will enter and exit the tunnels through the Maple Leaf Portal at First Avenue Northeast and Northeast 95th.