Sound Transit prepares to launch first Northgate Link tunnel boring machine

Written by Jenifer Nunez, assistant editor
image description
Sound Transit

Sound Transit crews are preparing to move the first Northgate Link light-rail tunnel boring machine (TBM) into launch position.


“This project will cut through some of the worst traffic in the state, creating the capacity to move up to 800 riders in each direction every few minutes with zero congestion,” said Sound Transit Board Chair and King County Executive Dow Constantine. “It will immeasurably improve the lives of its riders. It will also prove critical to the functioning of I-5 as the region’s population grows approximately 30 percent in the next two decades.”

The machine, which between 2011 and 2012 successfully completed two one-mile tunnels for the University Link light-rail project, is one of three TBMs that will help extend light rail 4.3 miles further north. The University Link light- rail project is currently scheduled to open in the first quarter of 2016, six to nine months early and is more than $100 million under budget. The $2.1-billion Northgate Link Extension, which will open in 2021, will run mostly underground through one of the most congested travel corridors in the region and includes underground stations serving the U District and Roosevelt 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 tunneling contractor is now finalizing the TBM assembly before moving it into launch position to complete final safety and operational checklists. The TBM weighs more than 1 million pounds and stretches more than 300 feet long, including the conveyor systems that remove the spoils.

The joint venture of Jay Dee Contractors, Frank Coluccio Construction Company and Michaels Corporation won the contract for the Northgate Link tunneling work with a proposal that was 25 percent below the engineer’s estimate.

Categories: OFF Track Maintenance, Rapid Transit/Light Rail