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The World’s Largest Drill Bit?

posted by rajbot on April 27th, 2007  

The 42-inch water main that carries water from the reservoirs into downtown San Francisco runs underneath our house. SFPUC is replacing it with a new one that doesn’t go underneath our house, and they are drilling a tunnel through Bernal Hill for the new pipe. A couple months ago they started digging a giant hole at the top of the street, which now goes down three or four stories. They call this the tunnelhead.

Recently, this weird equipment appeared next to the giant hole:
IMG_3236.JPG

On the other side of this thing is an opening with a chair that you can sit in:
IMG_3238.JPG

Here is a close up of the knobby bits:

Does anyone know what this thing is? Is it the world’s largest drill bit???

There isn’t a lot of information about the “Bernal Heights Water Pipeline Tunneling Project” on sfwater.org, but there is this map of the reservoirs and pipelines.

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3 Responses to “The World’s Largest Drill Bit?”

  1. shag
    April 30th, 2007 | 10:26 pm

    http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=83

    another big honkin drill bit

  2. rajbot
    April 30th, 2007 | 11:06 pm

    Tom sends this:

    Sure looks like a boring machine to me, resembles well drill heads I’ve
    seen in Prudhoe.

    Here’s a bigger one, 14.4 meters diameter to be specific, that looks
    similar and is being used to drill a tunnel near Niagra Falls. This is
    almost twice the diameter of the machine used on the chunnel!
    http://www.opg.com/power/hydro/new_projects/ntp/images/tbm1.jpg

    More about this machine here:
    http://www.opg.com/power/hydro/new_projects/ntp/ntp_gal.asp

  3. sss
    May 20th, 2007 | 1:43 am

    the world´s biggest drills are Tizona and Dulcinea 15 m.Ø
    they have just finished work in Madrid, Spain.

    http://en.wikipedia.org/wiki/Tunnel_boring_machine

    http://www.tuv.es/es/es/noticias/news26.php

    http://www.madridiario.es/mdo/actual/canales/distritos/archivo/arganzuela/tizona-210206.php

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