Sound Transit's tunnel-boring machine reaches daylight

SEATTLE – Sound Transit’s tunnel-boring machine “Brenda” punched through the north wall of the future Roosevelt Station on Tuesday — keeping the agency on track to open its Northgate light-rail extension by 2021, The Seattle Times reported.

The 21-foot, 6-inch diameter drill reached daylight around 4:30 p.m., after launching from the Maple Leaf Portal near Northgate in July. A joint venture of Jay Dee, Coluccio, and Michels is building the twin, 3.4-mile train tubes from Maple Leaf to Husky Stadium, plus the Roosevelt and University District stations, under a $462 million contract.

The breakthrough was supposed to happen before 9 a.m., but the machine slowed down while chewing through soil laced with concrete grout, to add stability near the station vault. Shortly after 11 a.m., Brenda took a break to cool off, before proceeding at no more than 5 millimeters per minute. For the full story, click here.