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 .