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The Boring Company FAQ

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Re: The Boring Company FAQ

#401

Post by euyyn »

sethrin wrote: post #328
prostoalex wrote: post #242

Earlier quoted context omitted.

> If America had better trains and subways, it could move massive amounts of people. Train automation is a solved problem, and currently implemented in cities around the world. In most European cities, if you get off at train station, you're in the midst of (or very close to) the city center, office locations, touristy walking sites and plenty of choices for retail or food. In the US once you get off at the train sta…

> NYC and SF are likely to be the only exception Portland should probably join that list.

And the Boston metro area.

Re: The Boring Company FAQ

#402

Post by Animats »

tpurves wrote: post #398
Animats wrote: post #61

So, the key ideas are: - Smaller diameter tunnels. 14' is suggested. This is slightly larger than the deep London Tube lines. - Electrically powered TBMs. Those exist. However, often the business end of the machine is hydraulically powered. Musk is probably thinking of going all electric, at least for the cutter head. After all, he has lots of experience with high-torque electric motors. - Do cutting and tunnel ring…

"- Soil variability. Very different techniques are required for different soils. Sometimes the soil has to be "conditioned", adding something to make it solid enough it can be drilled through.[1] This is the biggest practical problem in tunneling. Too much water is the usual problem." Too much water won't be a problem on Mars... where I think the end-game here is for Musk on why he's learning how to build tunneling m…

Fine, dry sand is also a problem. It leads to "over-excavating"; you keep digging and removing material as more slides down. You either get a big unwanted cavern that has to be supported, or break through to the surface.

Re: The Boring Company FAQ

#403

Post by sreya »

rsync wrote: post #388
hwillis wrote: post #218

Earlier quoted context omitted.

Air isn't really a problem. A person breathes about .5 cubic meters of air per hour, so 100 people trapped for 6 hours will go through 300 cubic meters of air. The diameter of the tunnel being 14', that air supply would take up 68' of tunnel lengthwise. And that's one breath, the air can be breathed many times before the co2 level becomes too high. The air inside the volume of a coffin can last you a few hours. Unles…

"The air inside the volume of a coffin can last you a few hours. Unless you are literally shoulder to shoulder with no other air, your oxygen will last as long as you need." ... unless there is a fire: "Most drivers rolled up their windows and waited for rescue. The ventilation system in the tunnel drove toxic smoke back down the tunnel faster than anyone could run to safety. These fumes quickly filled the tunnel and…

As niche as it might be, sounds like another point in favor of EVs no?

Re: The Boring Company FAQ

#404

Post by [deleted] »

rsync wrote: post #388
hwillis wrote: post #218

Earlier quoted context omitted.

Air isn't really a problem. A person breathes about .5 cubic meters of air per hour, so 100 people trapped for 6 hours will go through 300 cubic meters of air. The diameter of the tunnel being 14', that air supply would take up 68' of tunnel lengthwise. And that's one breath, the air can be breathed many times before the co2 level becomes too high. The air inside the volume of a coffin can last you a few hours. Unles…

"The air inside the volume of a coffin can last you a few hours. Unless you are literally shoulder to shoulder with no other air, your oxygen will last as long as you need." ... unless there is a fire: "Most drivers rolled up their windows and waited for rescue. The ventilation system in the tunnel drove toxic smoke back down the tunnel faster than anyone could run to safety. These fumes quickly filled the tunnel and…

[deleted]

Re: The Boring Company FAQ

#405

Post by crush-n-spread »

mangodrunk wrote: post #396
nmeofthestate wrote: post #376

I'm no starry-eyed admirer of The Boring Company, but it's funny how many peoples' argument here seem to be: "The Boring Company's plan to alleviate traffic congestion is flawed and non-optimal. It would make more sense to replace American cities with high-density ones and build mass transit instead".

Why is that funny? I see a proposal that requires cars as something that at best maintains status quo. A walkable/bikeable city seems far better to me than one that is made for cars. Roads are for cars instead of people. All that parking is for cars.

Yeah but people don't want that! No one is going to invest in getting rid of roads or giving away bicycles. That serves no one but the poor. People will invest in an underground transport network that solidifies Tesla's advantage.

Think about what will actually work, what is actionable. Getting rid of cars is completely unactionable. Tunnels are. So Elon does tunnels.

Re: The Boring Company FAQ

#406

Post by pjscott »

praptak wrote: post #240

"To solve the problem of soul-destroying traffic, roads must go 3D" This is not very convincing. Solving congestion by building more roads isn't exactly a new idea. Its track record isn't that glorious either: https://en.wikipedia.org/wiki/Induced_demand Not to sound too negative but how about some evidence on why it will work this time?

The induced demand argument applies to marginal increases in capacity on already-congested roads. If you make enough extra capacity, eventually you run into limits in how much demand can be created. For example, if you check out the city streets at 3 AM, you'll typically find that there's a lot more capacity than people are using.

These guys are quite ambitious in the scale of the tunneling they want to do.

Re: The Boring Company FAQ

#407

Post by Animats »

johnlbevan2 wrote: post #291
Animats wrote: post #61

So, the key ideas are: - Smaller diameter tunnels. 14' is suggested. This is slightly larger than the deep London Tube lines. - Electrically powered TBMs. Those exist. However, often the business end of the machine is hydraulically powered. Musk is probably thinking of going all electric, at least for the cutter head. After all, he has lots of experience with high-torque electric motors. - Do cutting and tunnel ring…

For the soil variability, is that hit when the TBM gets to a bad patch, is some kind of geophys carried out beforehand, or are there probe TBMs? I suspect having mini TBMs which go ahead of the main machine, boring small tubes would be an effective way to give feedback on what's coming up; avoiding nasty surprises / helping to prepare ahead of a change of soil type.

Soil testing by drilling small vertical test holes with well-drilling equipment is routine. This would be essential in Los Angeles, which is a mountain range covered by sedimentary basin fill. Here and there the mountain range peeks above ground, which is why you see some rock outcroppings in mostly flat LA. The mountain range is still there, underground.

It is well-mapped. LA used to have an oil industry, with oil wells all over the city. So the underground has been explored and studied by the oil industry. UCLA has been studying Los Angeles area geology since the 1920s.

Exploring horizontally has been done for a few projects that lack vertical access. Eurotunnel drilled the service tunnel first. Some mountain tunnel projects in Japan did horizontal test bores. You can't do this directly ahead of the main TBM without interfering with the main dig.

Re: The Boring Company FAQ

#408

Post by thaumaturgy »

maxerickson wrote: post #393
josephg wrote: post #148

Earlier quoted context omitted.

> But then we should ask why don't we do that anyway? Sure. Why didn't we have electric cars before tesla? Why didn't Boeing or Lockheed Martin make reusable rockets? Alan Kay said something[1] recently that has been bouncing around my head for the past few days. He said that many people think darwinian processes (like the economy) optimize. "One my degrees is in molecular biology, and I can tell you, any biologist w…

Why didn't we have electric cars before tesla? Mostly because batteries sucked. Small electronics drove most of the research to improve them. I guess Tesla vehicles are market leading in several ways, but they aren't a generation ahead of what anyone else can do or anything like that.

We should eliminate the things other agencies can do from discussions like this one. It's not about what other companies can do, it's about what they are doing. Sure, any major car manufacturer could produce a strong competitor to the Tesla, but they aren't.

Re: The Boring Company FAQ

#409

Post by jaclaz »

johnlbevan2 wrote: post #291
Animats wrote: post #61

So, the key ideas are: - Smaller diameter tunnels. 14' is suggested. This is slightly larger than the deep London Tube lines. - Electrically powered TBMs. Those exist. However, often the business end of the machine is hydraulically powered. Musk is probably thinking of going all electric, at least for the cutter head. After all, he has lots of experience with high-torque electric motors. - Do cutting and tunnel ring…

For the soil variability, is that hit when the TBM gets to a bad patch, is some kind of geophys carried out beforehand, or are there probe TBMs? I suspect having mini TBMs which go ahead of the main machine, boring small tubes would be an effective way to give feedback on what's coming up; avoiding nasty surprises / helping to prepare ahead of a change of soil type.

JFYT, that is a technique widely used, but normally not on tunnels that are (final diameter) TBM excavated, only or those that are excavaed through more traditional means (explosives/excavators). Basically if you want to excavate a tunnel (say) 12 m in diameter, you first bore a tunnel with a much more small TBM, typically 3.6 m in diameter.

This pre-bore provides three great advantages:

1) Ventilation of the tunnel during the enlargement is greatly simplified

2) You have a very sensible saving on explosives (if explosives are used) or however faster excavating times (because a large part of the amount of explosive is needed to "start" the demolition of the rock, i.e. pull the center "core" out)

3) From the pre-bore you can (when you encounter problematic terrain) drill radial holes for consolidation of the surrounding terrain (though cement injection or other similar techniques)

If the final diameter is TBM excavated as well, #1 advantage above is only partial, #2 is almost non-existing while of course #3 remains, BUT, you cannot make the pre-bore much smaller than the 3/3.6 m diameter as otherwise it would be only useful as a geo prospection mean, as it wouldn't be practical to use it for anything else, and there would surely be issues (for smaller diameters) with ventilation.

AND the other bad news are that - more or less and as a first approximation - a TBM has an operative tunnelling speed of roughly 400 m/month that is almost independent from the diameter (while a traditionally excavated tunnel is more around 100 m/month without pre-bore and 120/130 m/month with the pre-bore), so while it may make sense (of course a lot of factors are involved), if you have a 4 Km tunnel to make a pre-bore that will add roughly 12 month to your 50-60 months project excavation time (traditional), it won't make much sense unless for other very particular considerations to add those same 12 months to the 12 months a full face TBM would take.

What is often done on full face excavated tunnels with TBM is prospection holes (horizontal, drilled from the face of the TBM) in the 30-50 m range, to explore what lies ahead in the immediate future.

Re: The Boring Company FAQ

#410

Post by kerbalspacepro »

nmeofthestate wrote: post #376

I'm no starry-eyed admirer of The Boring Company, but it's funny how many peoples' argument here seem to be: "The Boring Company's plan to alleviate traffic congestion is flawed and non-optimal. It would make more sense to replace American cities with high-density ones and build mass transit instead".

I have to assume that the same set of people complaining about high rent prices because of NIMBYism are not the same people dismissing this solution, which has the subtext of being NIMBY-proof. But they're probably the same.
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