We Finally Found What's Blocking The World's Largest Tunneling Machine

Ever since the colossal machine tunneling under Seattle, nicknamed Bertha, was stopped in its tracks, there's been a frenzied speculation about what mysterious "object" could possibly block such a powerful machine. The answer is, at least partially, a steel pipe.

The pipe was the well casing for a 2002 groundwater study, preceding tunnel construction. While Bertha can easily chew through rock, it doesn't do so well with steel. Why the pipe was left in the ground and why officials didn't know it would be in Bertha's way is still its own mystery. Those speculating that some "piece of old Seattle" was blocking Bertha seem to be right, after all, even if the history is far more recent than they might have liked.

Update: Here's a photo of the pipe—all of 8 inches in diameter—protruding from the machine's cutterhead. Apparently, the crew had encountered pieces of metal in early December but continued tunneling until Bertha broke down. There's no plan yet for how to remove the pipe—or estimates for how long or costly the delay will be.

Sorry, steel pipe, but we might have liked you better as a mysterious object.


[Seattle Times]

Photo courtesy of WSDOT

Something Called "The Object" Stops World's Largest Tunneling Machine

Bertha, the world's largest tunneling machine, churning through the rock and mud beneath Seattle, has hit a mysterious roadblock—so mysterious, it is only known for now as "the object."

The New York Times reports that the machine—300 feet long and 5 stories tall—has ground to a halt. Built precisely not to be stopped by, well, just about anything, Bertha has apparently met her match. But what exactly is it? "Something unknown, engineers say—and all the more intriguing to many residents for being unknown—has blocked the progress of the biggest-diameter tunnel-boring machine in use on the planet," the NYT writes.

It is something the managers on site "still simply refer to as 'the object.'"

Some hypothesize a colossal ice age boulder or two, locked down in the sediments beneath the city. Others think it might be "buried train engines." Some think it might be Megatron—which would be fitting. After all, check out this incredible picture of Bertha under construction.


Some believe the city might even be interfering with itself, so to speak, unable to chew through its own past: "Some residents said they believe, or want to believe, that a piece of old Seattle, buried in the pell-mell rush of city-building in the 1800s, when a mucky waterfront wetland was filled in to make room for commerce, could be Bertha's big trouble."

What "a piece of old Seattle" really is is beyond me, as if a chunk of the metropolis had somehow collapsed into the ground below, like some strange, ingested tumor. But, whatever it is—fragments of architecture or just waste rock and rubble—Bertha has been trapped in its net.


Whether it's ice age super-rocks, buried trains, a lost city—or even a UFO—engineers might have to work "at atmospheric pressures similar to what a diver would experience," the New York Times adds, and even spend "time in a decompression chamber" on their way back up to the surface, to find out.

So what is it? What is "the object" blocking Bertha's path? Just look at the size of the tunnels it's been digging; whatever's in the way has got to be one tough mother. [New York Times]


Images courtesy of WSDOT.