DEP Invoice or Financial Record, September 30, 2001

NYC 9/11 Public Portal Document

all sides, and then this tunnel “box” was covered over with earth, some utility lines, sidewalks and streets. But each arch acts something like . an independent structure, and there are so many of them tliat tunnels remain intact even if many arches are destroyed. John Ferrelii, the chief of infra­ structure for the subways, said he saw the destruction from the deadly derailment of a No. 4 train at Union Square station in 1991, which knocked out supports from 28 arches

T>-94a. but caused the ceiling to sag hardly at all. Mr. Ferrelli, who walked through the damaged stations and tunnels on the 1 and 9 line last Friday, said so much of the line collapsed because ' the top of the 2 World Trade tower fell more to the side than the other tower. The debris crashed directly above the tunnel that ran along the northeast corner of the building, crushing a section about 375 feet long. “We basically had dozen,s of floors of a huge building falling from 600 feet right on top of our roof,” Mr. Ferrelli said. “It wa.s like a pile driver.” Inside the Cortlandt Street 1 and 9 station, he said, even where the plat­ form areas remain standing, inch­ thick I-beams fitted with inch-thick support plates are now wavy instead of straight. “To have the column buckle and the plate to twist like a Pringles chip, that takes a tremendous amount of force,” he said. He described walk­ ing toward the south end of the Cort­ landt Street station and noticing that the ceiling sloped closer to his head as he walked. “It wa.s a strange feeling," he said. The other area of total collapse is a stretch of about 200 feet north of the Cortlandt Street station, where the tunnel ran alongside the eastern side of 7 World Trade Center, the 48-story building that fell after the two trade center towers did. This is the portion that will have to be stuffed with concrete to secure the street above until debris is cleared and subway work can begin. The subway engineers, who have never confronted a job even a small fraction as complicated as the one that lies ahead, said they had no idea when they would be able to dig down and assess the full extent, of the dam­ age in the collapsed sections. They have even less of an idea when the reconstruction work can begin. The thing they do know, they said, is that the subway in that area could have survived the catastrophe only if decisions had been made 90 years ago to build it very deep below the city, the way that much of the Lon­ don Underground was built. Mr. Nagaraja, the chief engineer, said, “I don't think we could ever design the subway to withstand something like this."

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