How were the NYC subways built?

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ELI%: I know they were built around 1900, and that the city was not as populated, nor had as many buildings as today. I also know that train tunnels were built with dynamite to get through mountains. But Manhattan is an island. How did they create what is a massive rabbit warren under it? An elderly friend remembers the city taking down the elevated lines in WWII for metal recycling and she swears that the city had a lot more stops as well. Research keeps sending me to three articles, but none of them go into detail. Help please?

In: Engineering

2 Answers

Anonymous 0 Comments

The Sandhogs, the miners union for NYC, has been features in many interesting [documentaries](https://www.youtube.com/watch?v=gnwA0-9z9ho ). It’s a seriously dangerous profession, using explosives underground.

Anonymous 0 Comments

The majority of the system was built using the cut and cover method. Essentially, you dig an open pit down to the depth you want to subway tunnels and stations to be, and then build a ceiling on top that’s strong enough to support the weight of whatever is above it. Many lines run under streets, so they would excavate the area, build strong concrete and steel supports on top, and then pave the street right over that. Other parts were built using tunnel boring machines. A tunnel boring machine works kind of like an earthworm digging a tunnel. It’s a giant cylindrical machine that cuts up whatever rock is in front of it and pushed it out the back, leaving a circular tunnel as it moves forward.