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How does a TBM navigate then?

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Registered: 01-08-2007

How does a TBM navigate then?

Tunnel Boring Machines... like those used for digging out the chunnel and various underground lines in London.
How do they navigate from one end to the other with such precision? - Not only would you need a very precise map of everything else down there, you'd also need some way of navigating / referencing your previous waypoints down there and GPS isn't exactly reliable on the surface on a bad day.
So how do they do it down below the surface?
(I'm not asking how they make curved tunnels - i know they have difference shaped pieces for that, i'm asking how they adjust the course and hit the other end with such precision).
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Registered: 06-11-2014

Re: How does a TBM navigate then?

Gyroscopes, mathematics and clever people, that's how... Grin
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Re: How does a TBM navigate then?

For the big ones they use rams (not baa baa) to adjust the angle of cut of the cutting plate. For the HDD (horizontal directional drilling) they have eccentric drill heads or even a bent spade head which is angled in the desired direction then pushed forward rather than rotated.
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Re: How does a TBM navigate then?

Quote
An in-built laser guidance system enabled the tunnelling teams to ensure the machine remains on course, ending up to within a millimetre of where it needs to be.

http://www.crossrail.co.uk/construction/tunnelling/meet-our-giant-tunnelling-machines/#
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