Project update: Northgate Link Extension

TBM Pamela inches into the start of the future southbound light rail tunnel at the Roosevelt Station site. Meanwhile, a crew loaded into a specialized tunnel vehicle heads to work in TBM Brenda.

Tunneling update

Sound Transit’s contractor has successfully relaunched tunnel boring machine Pamela from the Roosevelt Station site to the U District Station site. Crews expect to hole-through in the U District by the end of the year.

Tunnel boring machine, Brenda, after a brief stop to repair the cutter head, is again making progress toward a fall arrival at the U District Station.

Tunneling support work picks up in Roosevelt

With two TBMs working southward, crews at the Roosevelt Station are busy providing tunneling support. Crews are currently working day and night to deliver tunnel liner segments, grout, water and other supplies from the Roosevelt site to the TBMs. Meanwhile, a conveyer system takes the muck all the way back the Maple Leaf portal site where it’s hauled away by truck.

Road work along tunnel alignment

Several other smaller construction sites have also sprung up along the tunnel alignment. These ½ block sites are spaced along city streets between the Roosevelt and U District stations. These sites are needed to stabilize the soil above where tunneling crews will eventually excavate emergency exits called cross-passages from one tunnel to the other. The cross passes will provide an evacuation route or shelter in case of a tunnel emergency.

Excavation complete at U District Station

With visits expected from two tunnel boring machines, crews at the U District Station site recently completed excavation and are pouring the station box’s concrete floor. They are also building the concrete pads that will help re-launch the two machines to the University of Washington Station.