khorum
Murder Apologist
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Yeah the deeper the tunnel the safer it is.
I used to work for the world's foremost tunnel builders, we ran project management for the UK's channel tunnel and nowadays they're the prime contractor for the largest urban infrastructure in the world, the Riyadh Metro Subway. For the Channel Tunnel, we designed the Siemens TBM that would simultaneously build the tunnel wall, lay new rail and drill a dozen feet of tunnel per hour---that's the "innovation" Musk's proposed TBM is supposed to do and it's been around since the early 90's.
There's really not much you can do to make tunneling cheaper that hasn't already been done. Generally you could make several narrower tunnels instead of one wide one, that would halve the costs since increasing the width of the tunnel raises the costs per kilometer exponentially. In fact, when trying to save the SSC project in Texas, we proposed shrinking the size of the primary ring by a third, which would've dropped the cost of the entire supercollider project by half. Eventually the LHC would have a smaller primary ring for the same reason.
Anyways, Musk would need to keep the tunnels as small as possible to cut costs to where this is something that would overcome the value proposition of just building more surface infrastructure. Making the tunnel smaller makes the TBM a lot faster too since it would need to assemble fewer prefab walls per meter and there would a fuckton less spoil to excavate behind it. Normally the spoil is conveyed out the back of the TBM by rail and waiting for the spoil reservoir to be emptied so it can start drilling again could take hours that it could otherwise be drilling (which is why most TBMs end up drilling only like 20 feet per hour max).
I used to work for the world's foremost tunnel builders, we ran project management for the UK's channel tunnel and nowadays they're the prime contractor for the largest urban infrastructure in the world, the Riyadh Metro Subway. For the Channel Tunnel, we designed the Siemens TBM that would simultaneously build the tunnel wall, lay new rail and drill a dozen feet of tunnel per hour---that's the "innovation" Musk's proposed TBM is supposed to do and it's been around since the early 90's.
There's really not much you can do to make tunneling cheaper that hasn't already been done. Generally you could make several narrower tunnels instead of one wide one, that would halve the costs since increasing the width of the tunnel raises the costs per kilometer exponentially. In fact, when trying to save the SSC project in Texas, we proposed shrinking the size of the primary ring by a third, which would've dropped the cost of the entire supercollider project by half. Eventually the LHC would have a smaller primary ring for the same reason.
Anyways, Musk would need to keep the tunnels as small as possible to cut costs to where this is something that would overcome the value proposition of just building more surface infrastructure. Making the tunnel smaller makes the TBM a lot faster too since it would need to assemble fewer prefab walls per meter and there would a fuckton less spoil to excavate behind it. Normally the spoil is conveyed out the back of the TBM by rail and waiting for the spoil reservoir to be emptied so it can start drilling again could take hours that it could otherwise be drilling (which is why most TBMs end up drilling only like 20 feet per hour max).
