The Crossrail tunnelling machines

FB

Not my cup of cake
Valued Member
Always thought it was a bit sad that the machines that built the channel tunnel were simply driven into the earth at the sides of the tunnels they had dug.
 

Brogan

🦶 Leg end
Staff Member
Probably the most economical solution as getting them out would have meant carving them up into small pieces and somehow transporting them back to one of the sink holes and lifting them out.

Once the tunnel lining is in place, the machine is actually larger than the tunnel.
 
Probably the most economical solution as getting them out would have meant carving them up into small pieces and somehow transporting them back to one of the sink holes and lifting them out.

Once the tunnel lining is in place, the machine is actually larger than the tunnel.

The world (and space come to that) is littered with truly phenomenal machines that deserve to be in museums being marvelled at for all eternity by hordes of schoolkids. The cost of recovery into a reusable condition is, however, simply unrealistic, even to recover, say, a TMB costing, say, $10m or mor - it's far cheaper to buy a new one
In the end the TBMs were diverted to one side of the tunnel they'd just dug, switched off, and walled in. Archaeologists will have a field day in a couple of thousand years time !


Talking of Canary Wharf, London is particular and it's frankly a miracle it has a tube system at all. It's because it's built on London Clay which is fairly easy to dig through but damp and bloody hard to keep stable when disturbed, unlike Manhattan which is based on basically granite which is tough to bore out but dry and stable.
There was a tunnelling job in, I think, Singapore, (somewhere like that anyhow) where the tunnellers had to drive their TBM through a gap between the foundations of two skyscrapers with only millimetres of margin of error. In the gap was a swimming pool, and they had to avoid the building foundations either side and avoid cracking the pool above their heads. You could almost hear the sphincters tightening!
 

Brogan

🦶 Leg end
Staff Member
The cost of recovery into a reusable condition is, however, simply unrealistic, even to recover, say, a TMB costing, say, $10m or mor - it's far cheaper to buy a new
And yet, from that link...

Once their work is finished, the machines will be sold back to their German manufacturer Herrenknecht and refurbished for further use.


Speaking of tunnels, I was friends with a guy who was working on the Denmark-Sweden tunnel about 10 years ago.
There were three pumps to keep the water out: one in service, one being overhauled, and a spare.
After a few months all three pumps were operating at full capacity all the time...
Needless to say I didn't use the tunnel :D
 

FB

Not my cup of cake
Valued Member
I presume the Cross Rail machine will come out at the other end of the tunnel but the Channel Tunnel met in the middle so getting the machines out from Cross Rail might be a bit easier.
 
And yet, from that link...




Speaking of tunnels, I was friends with a guy who was working on the Denmark-Sweden tunnel about 10 years ago.
There were three pumps to keep the water out: one in service, one being overhauled, and a spare.
After a few months all three pumps were operating at full capacity all the time...
Needless to say I didn't use the tunnel :D

Reuse - or even recoverability in the first place - does depend on so many factors of which a viable exit route can be impossible in economic or practical terms but, yes, doesn't have to be in all cases.

And if I ever find myself doing the Denmark Sweden crossing I might take the ferry too. As long as it isn't called the Costa Anything !
 
In these days of laser precision and sat nav and all the other electronic crap that we can't do without, let's not forget Joseph Bazalgette who had sewage/drainage tunnels built under London in the 1860s with only spirit levels and measuring staffs (staves?) and still managed to get two opposing tunnelling teams to meet in the middle with only 1" or 2" difference between the bores when they knocked through.
Now that, in those days, IMO, is truly ****ing incredible!
 
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