WTF?!? Under Seattle, a Big Object Blocks Bertha. What Is It?

[link to www.nytimes.com]

SEATTLE — A secret subterranean heart, tinged with mystery and myth, beats beneath the streets in many of the world’s great cities. Tourists seek out the catacombs of Rome, the sewers of Paris and the subway tunnels of New York. Some people believe a den of interstellar aliens lurks beneath Denver International Airport.

Bertha in May, before it was lowered underground to start digging.

Now Seattle, at least for now, has joined that exclusive club.

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, a high-tech, largely automated wonder called Bertha. At five stories high with a crew of 20, the cigar-shaped behemoth was grinding away underground on a two-mile-long, $3.1 billion highway tunnel under the city’s waterfront on Dec. 6 when it encountered something in its path that managers still simply refer to as “the object.”

The object’s composition and provenance remain unknown almost two weeks after first contact because in a state-of-the-art tunneling machine, as it turns out, you can’t exactly poke your head out the window and look.

“What we’re focusing on now is creating conditions that will allow us to enter the chamber behind the cutter head and see what the situation is,” Chris Dixon, the project manager at Seattle Tunnel Partners, the construction contractor, said in an interview this week. Mr. Dixon said he felt pretty confident that the blockage will turn out to be nothing more or less romantic than a giant boulder, perhaps left over from the Ice Age glaciers that scoured and crushed this corner of the continent 17,000 years ago.