3. The 485-Ton Tunnel Diggers
Constructing subways are herculean mega projects that involve digging through miles of city bedrock while keeping the foundations of the building above intact. In order to accomplish this the MTA (and construction companies around the world) have been utilizing state-of-the-art tunnel boring machines (TBM) that can dig through bedrock at a remarkable pace while causing minimal disturbances on the grounds surrounding the tunnel.
During the past years, a fleet of seven behemoth TBMs have been excavating tunnels for both the new Second Avenue line, East Side Access, and other transit projects. These gargantuan machines excavate tunnels using the sharp, tungsten carbide shears of the cutting head. The excavated material from the tunnels is then sent back via a belt conveyor. Next, the TBM pushes forward and segments of concrete are placed on the walls of the newly excavated tunnel. The equipment for the machine extends the length of a few city blocks in the back.
The machines also have their own distinct names that have interesting origins. Adi, named after the granddaughter of Michael Horodniceanu, the agency’s president of capital construction, was refurbished and shipped to Indianapolis after it finished work on the Second Avenue line in September of 2011. Weighing 485 tons with a 200-ton cutting head, Adi is the machine that mined almost 15,000 feet of the new line, from 92nd Street to 63rd Street, at a rate of 50 feet per day.
The tons of muddy crushed rock that is created by digging, known as muck, has been put to good use. The muck has been used as foundations for new college dorms in Jersey City, stables soil under a golf course, and a fill that created parts of Brooklyn Bridge Park!