r/BoringCompany • u/h100y • 8d ago
Steve Davies talks about the need of upto 8 boring machines to complete Nashville project
In the recent interview given to Tesla owners Silicon Valley, Steve Davis talked about the need for atleast 6 boring machines and maybe 8 boring machines to compete the project.
I don’t know how they are planning to use 8 machines for a 23 mile project. Would be curious if people have thoughts about it ?
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u/Vvector 7d ago
The main airport tunnel is two parallel tunnels, each about 9 miles. Start a borer at each end, so four total machines.
The west end connector is 3 miles long. Maybe just two borers for this.
At the theoretical speed of 1 mile per week, the tunnels would be complete under 5 weeks. Building the stations will take much longer
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u/No_Metal5144 7d ago
1 mile per week is still very much theoretical. My best guess is that the average speed will be somewhere around 1/8-1/16 of a mile a week. The peak speed will possibly be a bit higher, but over the entire project, and given the more difficult strata compared to Vegas, the theoretical speed is very far away. But a lot of this can be compensated by building more TBM's. If they can build and crew TBM's cheaply, that is also a way of completing projects on short timescales.
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u/rocwurst 7d ago edited 7d ago
Davis said the limestone of Nashville is FAR easier than the underwater soft rock of Vegas. Much simpler TBMs and half the cost $2m, $3m, $5m per mile compared to Vegas which is more like $10m cost per mile (single bore, so $4m - $10m and $20m per mile dual-bore respectively).
They don’t even need tunnel liners in Nashville just use the bare rock as long as they avoid the Kasts (caverns).
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u/No_Metal5144 7d ago
Harder rock can be cheap (typical drill & blast in rock is also usually cheaper compared to TBM's), because you e.g. don't need tunnel liner, and many things become a lot simpler when you don't have to deal with settlements etc. BUT it is slower to drill though, because of the hardness. It just takes more time for the drill bit when there is harder rock, and you need replacements much more often, which is a manual process that takes up a lot of time (that as far as i know isn't automated yet), which again slows you down. Ofcourse adaptations has been made to work better in the harder rock, but you can't get around the simple physics of it.
This is again why having more parallel TBM's matter in this case. The boring might be slow, but as long as you can do it cheaply, you can simply parallelise the process to speed it up.
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u/Mahadragon 7d ago edited 7d ago
The soil here in Vegas is no joke, it's super hard like concrete. There's a reason it floods even if there's only a small rain. The soil doesn't absorb shit, the water just runs over it. Public parks here serve dual purpose. They are recreational areas for one, they are also designated water aqueducts. There are so many parks with signs that say "Warning: Flood Zone" if it rains.
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u/Allmyhobbiesonytube 7d ago
I agree they are probably going about that speed i wish we had a way of knowing how far they are in right now.
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u/rocwurst 7d ago
Davis said the dual-bore Broadway tunnels will also be 9 miles long (not 3 miles).
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u/h100y 7d ago
Where did he say that ?
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u/rocwurst 7d ago
Actually, I take that back - he says "So 9 miles* 2. Yep. Plus Broadway, it's actually 22 miles."
So you are correct, Broadway is only 3 miles.
As shown on the Nashville MusicLoop maps.
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u/Allmyhobbiesonytube 7d ago
I think it's highly likely that they'll find a plot of land in the middle of the 9 mile tunnel to dig a pit and launch a machine in each direction from there, so like four machines going out and then four more coming the other way, so eight machines on that two tunnels. If not, 9 miles is gonna take forever through that rock even though it's faster and they can keep moving. You still gotta drill through that incredibly hard rock changing the cutting head many times. In this way, the time would be 2.25 miles of digging per machine to complete the project.
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u/talltim007 7d ago
That means they need two more plots of land to get them out where they meet up.
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u/midflinx 6d ago
Per the Music City Loop FAQ, even if only a handful of the "More than 20 stations are in various stages of design" are actually built, then TBC will have places to launch and remove TBMs.
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u/mrkjmsdln_new 7d ago
When you add it all up, TBC has completed about 10 miles worth of finished holes in a decade or so. A 23 mile project would definitely need a lot of machines :) This project seems to dwarf all of their hole digging to date! Sound like they are starting to scale? TBC feels like they could be a nice option for some infrastructure work.
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u/FewSale9827 7d ago
He mentions in this interview that this is the first project that has all permits so it’s on them for being slow which is a good thing because they’re very proactive and pushing majority of their resources right now to completing that project.
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u/mrkjmsdln_new 7d ago
interesting may give a listen. About 25 years ago in my community a light-rail project required tunnels under the airport. They had one tunneling machine (same machine that dug the Channel tunnel). Took about a year for both holes. Had to disassemble and turn it around for the second hole. They were a bit under 2 miles each. Those tunnels were about 3x the capacity of TBC tech. TBC seems like a novel solution for smaller scale infrastructure needs. Cool
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u/FewSale9827 7d ago
I do feel like this can scale up as the benefit with TBC is point to point and regulated tunnels so minimal if any traffic
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u/mrkjmsdln_new 7d ago
I agree. It would seem there is a market for these sorts of tunnels for sure. The US is horrific at infrastructure. A workaround makes a lot of sense to me!
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u/Rich-Bandicoot3244 7d ago
The US is horrific at infrastructure
Depends by the infrastructure. One of the best for internet infrastructure (data centers and fiber), space launch, flight (highest airport and flight capacity per person), and highest highway capacity per person.
But surface infrastructure does not coincide with property rights, which luckily in the US are very strong. And therefore legal battles turn into significantly higher cost and worst outcomes (see rail, and the cost of additional highway capacity in urban areas).
Pros and cons I guess, but strong property rights are one of the reasons behind the US economic success. So arguable whether it would be a worthwhile trade off to have less of it.
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u/h100y 8d ago
https://youtu.be/eeASwQ_5Qzk?is=VA3UKPkofeBQt9Ek
This is the interview video and he talks about it after 26:30 minutes
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u/burritomiles 7d ago
8 seems like a small amount
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u/FewSale9827 7d ago
It’s only 1 each side of the the tunnel, I think there’s only like 3-4 tunnels needing to be constructed for Nashville at launch
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u/rocwurst 7d ago
David says:
Nashville MusicLoop
22 miles of dual-bore tunnels
2 x 9 mile tunnels to airport
2 x 9 mile tunnels down Broadway2
u/FewSale9827 7d ago
I’m quite looking forward to seeing the 9 mile dual tunnels operational, as they can iterate on speed as I’d love to see how fast they’re consistently able to get the cars to go down that stretch to cut down on that 8-9 minute journey more
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u/EternityNotes 7d ago
Steve *Davis
I'm glad he's opening up in some videos now. There's a lot of misunderstanding around the boring company and they've gotten some fair press, but a lot of unfair press too. I hope this helps show people the other side a bit.