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Comment by chx | Hacker News Reader

What the article mentions in passing was called "threading the needle" where an earth pressure balance tunnel-boring machine mined the section of tunnel directly above the operational Northern line platform tunnels at Tottenham Court Road, directly below the London Underground station structures, with less than 800mm clearance to each. Read more at https://www.theengineer.co.uk/content/in-depth/your-question...

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Wait what? There are three tunnels under London separated by a two feet of earth?!

I doubt we even need a Bond villain to break through that !

I am not sure I trust engineering that much?

They posted an engineer (and a film crew[1]) to stand on the relevant platform at Tottenham Court Road while the TBM was boring through, to watch for anything going wrong. That's trust :)

1. For this documentary. The title hasn't aged well... : https://www.bbc.co.uk/programmes/b08ry6fy

I wonder if the Bond villain is responsible for the late opening of the eponymous Station?

It's more, is that going to hold for a hundred years? I mean it's just ... clay under London.

Then again what do I know. I look up at Jumbo Jets flying past and think, "no way can that stay up there"

If we turn out to live in the Matrix and heavier than air flight is done with a continuous loop in a Perl script, I will not be surprised.

make the project engineers who signed the plans stand there.

Not quite sure what your problem is, the tunneling was dicey but once it's done, it essentially becomes a concrete pipe.

It’s not as impressive if you know that we can use ultrasound to know how far away we are from the tunnels in the first place

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