4 ms·

Has the Boring Company even said anything about how they plan on so dramatically cutting the cost per mile of tunnel building?

bryanlarsen 8y ago
They're not making it dramatically cheaper, they are using sewer tunnel boring machines at a cost similar to that of boring a sewer tunnel. The innovation is the assertion that such small tunnels are sufficient and safe for mass transit.
Arnt 8y ago
Yes. Boringco's final cost per person and km isn't known yet, but it's not obviously a major win compared to good current practice, such as what you can read about here: https://tunnelbuilder.com/metrosur/edition2pdf/page2.pdf https://tunnelbuilder.com/metrosur/edition2pdf/page2.pdf
larkost 8y ago
Yes, there is a pretty good video of an interview with Musk and the chief engineer on the project: https://www.youtube.com/watch?v=AwX9G38vdCE https://www.youtube.com/watch?v=AwX9G38vdCE From memory, the important points: 1. They want to have the drill work continuously. Apparently current technology winds up drilling less than half the time, partially because the drills stop when putting in the wall sections that make up the tunnel. 2. Switch the drill and the waste train (that takes the dirt from the drill) to electric using batteries that the train brings in. This reduces the construction of pipes and infrastructure in the tunnel during construction. 3. Work to speed up the drill head by using the materials scientists from SpaceX. 4. Make bricks out of the waster material on-site. Right now disposing of the waste material is a big headache/cost.
- gamblor956 8y ago
  The thing that Elon and his "chief engineer" did not bother to learn before making that video is that boring machines are already electric. They are merely suggesting replacing the electrical wires with batteries. The consequences of this is that the drill still only drills half the time, because you have to stop to swap out batteries. And unless Elon has access to superbatteries that he hasn't revealed yet, they'll be swapping batteries once or twice an hour for any boring machine large enough to construct subway-sized tunnels. Also, the reason the drill stops to put in walls sections every X feet is because in soft-soil like LA, the tunnel will collapse without walls. Unlike the Elontunnel, the walls built by the machine during this stage are the final walls, which is why they take so long--they're subject to the full construction process (measuring, building, remeasuring, inspections, sign-offs, etc.) before the tunnel digs a new section. When you're digging under other people's property, it's better to go slowly and do things right the first time. It's more expensive to fix something like a tunnel after the fact, and that's something BoringCo is about to learn. As for number 3: different materials require different drill heads and speeds. For example--with soft soil drilling to fast can "liquefy" the soil. Material science won't change that--it's physics that the boring industry has decades of research in.

bryanlarsen 8y ago

They're not making it dramatically cheaper, they are using sewer tunnel boring machines at a cost similar to that of boring a sewer tunnel. The innovation is the assertion that such small tunnels are sufficient and safe for mass transit.

Arnt 8y ago

Yes. Boringco's final cost per person and km isn't known yet, but it's not obviously a major win compared to good current practice, such as what you can read about here: https://tunnelbuilder.com/metrosur/edition2pdf/page2.pdf https://tunnelbuilder.com/metrosur/edition2pdf/page2.pdf

larkost 8y ago

Yes, there is a pretty good video of an interview with Musk and the chief engineer on the project: https://www.youtube.com/watch?v=AwX9G38vdCE https://www.youtube.com/watch?v=AwX9G38vdCE From memory, the important points: 1. They want to have the drill work continuously. Apparently current technology winds up drilling less than half the time, partially because the drills stop when putting in the wall sections that make up the tunnel. 2. Switch the drill and the waste train (that takes the dirt from the drill) to electric using batteries that the train brings in. This reduces the construction of pipes and infrastructure in the tunnel during construction. 3. Work to speed up the drill head by using the materials scientists from SpaceX. 4. Make bricks out of the waster material on-site. Right now disposing of the waste material is a big headache/cost.

gamblor956 8y ago
The thing that Elon and his "chief engineer" did not bother to learn before making that video is that boring machines are already electric. They are merely suggesting replacing the electrical wires with batteries. The consequences of this is that the drill still only drills half the time, because you have to stop to swap out batteries. And unless Elon has access to superbatteries that he hasn't revealed yet, they'll be swapping batteries once or twice an hour for any boring machine large enough to construct subway-sized tunnels. Also, the reason the drill stops to put in walls sections every X feet is because in soft-soil like LA, the tunnel will collapse without walls. Unlike the Elontunnel, the walls built by the machine during this stage are the final walls, which is why they take so long--they're subject to the full construction process (measuring, building, remeasuring, inspections, sign-offs, etc.) before the tunnel digs a new section. When you're digging under other people's property, it's better to go slowly and do things right the first time. It's more expensive to fix something like a tunnel after the fact, and that's something BoringCo is about to learn. As for number 3: different materials require different drill heads and speeds. For example--with soft soil drilling to fast can "liquefy" the soil. Material science won't change that--it's physics that the boring industry has decades of research in.