TBM

An equipment has been brought from Germany. I went to see it work yesterday. It is called a Tunnel Boring Machine (TBM). It is quite similar to the one used in laying tracks underground in Metro Railway projects like East West Metro. See http://principalsecretarysblog.blogspot.in/2012/01/tunnel-boring-machines-arrive.html

The TBM enables pipes to be laid underground without cutting the road surface. The pipe is six feet wide, made of thick steel and encased in concrete. A water jet cuts the earth around the pipe and slurry is pumped out while a huge pressure - 53 bars yesterday while we were there - is exerted to drive in the pipe. It is laser guided to keep it straight. The concrete jacket helps resist the pressure. Later, people will go inside the pipe to weld the joints to prevent water leakage.
This is part of the project for bringing in water from Hoogly to New Town and elsewhere. A picture on my mobile:

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A clipping :