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>>> you can scale by buying more TBNs putting them in a line and having each meet up to the next What I'm picturing from your statement is two TBM drilling tow
by jonwachob91 7y ago
>>> you can scale by buying more TBNs putting them in a line and having each meet up to the next
What I'm picturing from your statement is two TBM drilling towards each other like ---> <----.
Which would require the digging of a third hole where the TBM "drill heads" meet. After every TBM dig, the drill heads are left at the end of the tunnel b/c they are bigger than the new tunnel (as the head digs the tunnel, workers install support structure to prevent a collapse, so the just drilled tunnel is smaller than the being drilled tunnel). A 3rd dig would be required where the two TBM drill heads meet to retrieve them and connect the tunnels. That's a lot of $$$ :/
- bluGill 7y agoI was thinking same direction ---->---->. Though as the other poster pointed out, often you are going under something and so you can't do that - the English channel did what you propose and there are thus tunneling boring machines under the channel.
- Swannie 7y ago> Which would require the digging of a third hole where the TBM "drill heads" meet. In most projects it's called a station. http://www.crossrail.co.uk/construction/tunnelling/meet-our-giant-tunnelling-machines/ http://www.crossrail.co.uk/construction/tunnelling/meet-our-... Occasionally you'll have dive sites that are not at/near stations, but not that often. https://www.sydneymetro.info/station/blues-point-temporary-retrieval-site https://www.sydneymetro.info/station/blues-point-temporary-r... https://www.sydneymetro.info/tunnelling https://www.sydneymetro.info/tunnelling