Sound Transit announces second TBM launch

27 November 2014

USA - The TBM mining light rail tunnels from the Northgate neighborhood in Seattle to the University of Washington launched on November 20.

"Northgate Link is expected to be one of the busiest new light rail lines in the nation," said Sound Transit Board Chair and King County Executive Dow Constantine. "The action we're taking today will help us meet the increasing demand on one of the most popular corridors in the central Puget Sound region."

The Northgate extension is expected to add more than 60,000 riders a day to the light rail system by 2030 and be a key component of a region-wide light rail system that will carry an estimated 280,000 riders a day by 2030.

Sound Transit contractors are using two TBMs to mine the twin Northgate Link tunnels. The first TBM launched in July and has mined about 3,200 feet so far.

The machines will mine approximately 3.6 miles from the tunnel portal just south of the Northgate Transit Center to UW where the tunnels will connect with the University Link line into downtown Seattle. That section between downtown and the UW is scheduled to open in early 2016.

The $2.1 billion Northgate extension includes underground stations in the U District and Roosevelt neighborhoods and an elevated station at Northgate. The line will add major new capacity to the region's transportation system, offering fast, frequent and congestion-free service 20 hours a day. A trip from Northgate to downtown will take 14 minutes. Northgate to UW Station will take eight minutes.

The tunnels are being constructed by the same contractors, Jay Dee Contractors of Livonia, Mich., Frank Coluccio Construction Company of Seattle, and Michaels Corporation of Brownsville, Wis., that successfully completed two one-mile tunnels for the University Link light rail project. The University Link light rail project is currently scheduled to open in the first quarter of 2016, six to nine months early, and is estimated to be completed approximately USD 150M under budget.