Bertha, the huge machine currently boring a two-mile tunnel 200 feet beneath Seattle, returned to work this week after surveyors discovered that it was "several inches" off course. But that's not completely unusual, apparently, and it sounds pretty tiny compared to the scale of the project. Just look at this thing, thanks to the Washington State Department of Transportation's new 3D camera, via GeekWire:
The five-minute, 1.5-mile ride along with the massive machine also goes inside the control room, which "few people ever get to see," says our guide, Joe Hedges, a project administrator with the Alaskan Way Viaduct Replacement Program. Positioned 40 feet behind Bertha's cutter head, we watch as one of the tunnel's 18-ton ring segments is installed to form its outer wall.
Named after Seattle's only female mayor, Bertha began in the summer of 2013 (compare that with the timeline of New York's Second Avenue Subway) and is now just two blocks from the "receiving pit," where it's expected to emerge in May. When it opens, sometime in 2019, the $2.1 billion tunnel will replace the elevated Alaskan Way Viaduct highway, which experts have warned for decades is vulnerable to severe damage from earthquakes. In a 2017 "infrastructure report card" published today by the American Society of Civil Engineers, the nation's overall infrastructure gets a grade of D+.
[Screenshot via WSDOT] AP