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In a Cavern Below Second Ave., Exploding & Moving the Earth

For all the complaints about the Second Avenue subway, from the delays to the construction commotion, there's no denying that what the 475 laborers are doing beneath Manhattan is impressive and even a little mindboggling. The massive tunnel-boring, rock-eating mechanical worms may do the heavy lifting, but there is still no way to mine a tunnel without sending men into it. The Times recently went underground with these men, capturing their work on film and in photos. Testing the stability of the ground is crucial, and under 92nd Street, the crew encountered soil and crumbling rock, which, if they simply settled the ground and dug right through, it would collapse the buildings above. Instead, they had to freeze the earth by pumping a constant stream of minus-13 degrees calcium-chloride brine into the ground for 10 weeks. Only then could they cut the tunnel.

A brief history of the Second Avenue Subway, which began more than 80 years ago, when the line was first proposed:

It would run from 125th Street south to Houston and cost $86 million. Then came the Great Depression. Then World War II. Then existing subways needed repairs. In the early '70s, short sections of the Second Avenue tunnel were burrowed at the foot of the Manhattan Bridge, between 99th Street and 105th and between 110th and 120th, before the city's looming bankruptcy in 1975 halted all digging. The dream of a Second Avenue subway lay dormant until April 12, 2007, when contractors for the MTA again broke ground?to extend the Q line from 63rd and Lexington over to Second Avenue and up to 96th Street. That alone costs $4.5 billion. Eventually they will lengthen the Q to 125th and dig a new line, the T, from the Financial District straight up Second Avenue to 125th Street.But what's even more interesting than the stop-starting of SAS, is this bit about the first prototype subway station built in 1870: "When Alfred Ely Beach, the publisher of Scientific American, built a blocklong prototype subway in 1870, he dragged chandeliers and a grand piano down to distract riders from fears about hell-demons or vermin."
· Tunneling Below Second Avenue [NYT]
· Second Avenue subway coverage [Curbed]