NEW YORK » Rome has the catacombs; Paris has its sewers. Now New York will have its own subterranean wonder: a 200-ton mechanical serpent’s head.

It is a gargantuan drill that has been hollowing out tunnels for a train station under Grand Central Terminal. As tall as four men and with the weight of two whales, the cutter head — the spinning, sharp-edged business end of a tunnel boring machine — is usually extracted, dismantled and sold for scrap when the work is done.

But the Spanish contractor overseeing the project is taking a different approach. It believes it can save time and money by simply leaving it behind, dormant and decayed, within the rocky depths of Midtown Manhattan. The drill’s final resting place: 14 stories beneath the well-tended sidewalks of Park Avenue.

There is little precedent for such a Brobdingnagian burial. No one at the Metropolitan Transportation Authority, which plans to officially entomb the machine sometime this week, can recall such an interment. "It’s like a Jules Verne story," Michael Horodniceanu, the authority’s chief of construction, said.

A recent visit to the cutter’s future crypt revealed a machine that evokes an alien life form that crashed to earth millennia ago. Its steel gears, bolts and pistons, already oxidizing, appeared lifeless and fatigued. A wormlike fan, its exhaust pipe disappearing into the cutter’s maw, was still spinning, its drone not unlike a slumbering creature’s breath.

"If you came and visited this 100 years from today, this is what you’d see," said Horodniceanu, balancing on a catwalk that overlooks the enormous contraption. "People would not know what it’s all about."

The cutter head, known as Seli after its Italian manufacturer, has been eating its way through several miles of Manhattan schist since 2007. Its flat face is equipped with 45 rotating discs, each carrying a layer of tungsten carbide, an exceptionally strong alloy that can easily break through the city’s bedrock. (Rumors that the machine used diamonds for this purpose were "an urban legend," according to a transportation authority spokesman.)

Starting in 2016, the 22-foot-diameter tunnels created by the cutter will carry thousands of Long Islanders into a station beneath Grand Central Terminal. Today, the passages are craggy and unfinished, suggesting the ominous, organic look of a monster’s cave.

Seli cost $6 million to $8 million, but Dragados, the project’s chief contractor and operator of the machine, decided this year that a scrap sale would not be economical. It can take months to dismantle a cutter, and the parts would have to be hauled from Midtown to the tunnel’s other end in Queens. The removal would delay further construction, potentially costing millions of dollars in additional wages.

"It costs, in effect, $100,000 a day just to be there — to say, ‘Hello!"’ Horodniceanu said. "A machine like this, they want to spend $9 million pulling it out? You must be kidding me. It’s not happening."

Burial is more common for cutters in international tunneling projects. But the approach has rarely been tried in New York, whose crowded underground does not often have room.

The new Second Avenue subway line ends at the 63rd Street F train station, not an ideal cemetery plot. On the No. 7 line, which is being extended to the far west side, the burial would have to take place beneath the Port Authority Bus Terminal, "and you can’t bury it in the Port Authority, very simply put," Horodniceanu said.

But the grassy Park Avenue median, between 37th and 38th streets, did not pose a problem. And extracting the cutter from that location was out of the question. "There would had to have been a 40-foot-diameter shaft right in Park Avenue, in front of the Union League Club, to pull it out," said Mark Rhodes, an engineer on the project.

In an official ceremony this week, the cutter will be sealed off by a concrete wall; the chamber will then be filled with concrete, encasing the cutter in a solid cast, Han Solo-style, so that it can serve as a support structure for the tunnel. A plaque will commemorate the site. A spokesman said the pouring of the concrete was expected to take place on Wednesday.

© 2011 The New York Times Company