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The Boring Company FAQ

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Re: The Boring Company FAQ

#61

Post by Animats »

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 assembly simultaneously. Some TBMs already do that. Those exist; they're called double-shielded TBMs.

Issues glossed over:

- 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.

- The back end. TBMs are long machines. The front end does cutting and ring assembly. The back end, which can be several hundred feet long, is mostly material handling. There's usually a two-track narrow gauge railroad behind the TBM, carrying ring segments forward and dirt backwards. It's constantly being extended with new track sections. That's part of the TBM's job.

Here's a good overview of TBMs design, from Machine Design.[2]

[1] http://www.therobbinscompany.com/wp-content/uploads/2014/08/... [2] http://www.machinedesign.com/archive/art-digging-hole

Re: The Boring Company FAQ

#63

Post by iamacynic »

Fricken wrote: post #55

So in the concept video it shows passengers loading on to a sled at surface level that can hold maybe a dozen people, and then it descends on an elevator 50 metres to the tube and goes down the line. This sounds cost effective compared to a full on underground subway station, which really aren't cheap to build even if you 10x the cost of tunneling, but it isn't good for much unless all those passengers intend to also…

> that can hold maybe a dozen passengers

there's no reason this system couldn't carry a bus.

musk markets to the elites first, then uses that to subsidize the mass market solutions.

Re: The Boring Company FAQ

#64

Post by gosheroo »

avn2109 wrote: post #42
gosheroo wrote: post #30

If speed is key, what about developing nuclear-powered TBMs?

Many TBM's are already nuclear powered, in that the grid power they consume was generated in a reactor somewhere. There is no reason to bring the reactor closer to the dig site. Also, see e.g. https://en.wikipedia.org/wiki/The_Core for prior art /s

Using the grid there must be a lot of transformers and cabling involved. Plus with massive amounts of power in situ one might be able to process the waste rock differently (e.g. if it's looser material with fissures, compress it against the sides of the tunnel or perhaps even melt it rather than removing it. Admittedly I'm rather ignorant of soil and rock physics.)

Re: The Boring Company FAQ

#65

Post by econnors »

Fricken wrote: post #55

So in the concept video it shows passengers loading on to a sled at surface level that can hold maybe a dozen people, and then it descends on an elevator 50 metres to the tube and goes down the line. This sounds cost effective compared to a full on underground subway station, which really aren't cheap to build even if you 10x the cost of tunneling, but it isn't good for much unless all those passengers intend to also…

I think you're right that stops will be longer, but it's my understanding they'll also be less frequent and they'll cover greater distances than a regular subway track (in say, NY). So you'll end up getting there faster and not have the stress of driving in traffic.

Re: The Boring Company FAQ

#66

Post by mrout »

discodave wrote: post #48

The old strategy of hiding your outlandish claim in an assertion in the first sentence! "To solve the problem of soul-destroying traffic, roads must go 3D" The word "must" is a very strong one here, there are other options: * Reduce the amount of travel that people need to do (remote work, online shopping). * Reduce the density of cities (enabled by remote work or longer commutes with better internet access). * Incre…

>Reduce the density of cities (enabled by remote work or longer commutes with better internet access).

I hope you mean increase the density of cities. Low density is what creates bad traffic. Sprawling cities like LA and Auckland in NZ have awful, awful traffic while dense cities have much more manageable traffic, as public transport is viable.

Re: The Boring Company FAQ

#67

Post by jp_sc »

URSpider94 wrote: post #37
shpx wrote: post #9

Doesn't a tunnel under a building significantly increase the chances of the building falling down? What about flooding?

No, it doesn't. If it did, buildings in NYC would be falling down left and right. Heck, I hear they even put them under entire bodies of water! Yes, tunnels can flood, if they are below the water table. Good pumps can fix that problem. Again, the Chunnel being Exhibit A - it hasn't flooded, yet.

Isn't most of Manhattan ground solid rock? There are many other places where the ground it's just compressed dirt

Re: The Boring Company FAQ

#68

Post by mrout »

theprop wrote: post #21

This is FANTASTIC! It's important to understand how massive the Earth is (even though it's a pinprick when compared to the sun). You can EASILY go 3-D or deep. The deepest mines in the world are around 12,000 feet deep. This is about 6x the height of the tallest building in the world (2000 feet tall). Imagine, thus, putting in a tunnel at what would be every 5th floor of a skyscraper and that you could fit 6 skyscrap…

It's literally hundreds of times more expensive to dig underground than build up. Underground is a public space, it should be reserved for public transport.

Re: The Boring Company FAQ

#69

Post by josephpmay »

so33 wrote: post #45
CodeWriter23 wrote: post #32

Earlier quoted context omitted.

This IS public transit. Public transit without the last mile (or in LA, the last 5 miles) problem. This freedom-supporting tech also thwarts the tyranny inherent in public transit (schedules, robbing your life with all the waiting, limited load carrying capacity, forced interactions with antisocial individuals, etc.)

But there is still a last mile problem, you have to enter and exit out of the tunnels. That's the last mile. Or do you suggest that tunnel building will become so viable from an economic and engineering standpoint that everyone will have an entry point in their garage? > This freedom-supporting tech also thwarts the tyranny inherent in public transit (schedules, robbing your life with all the waiting, limited load ca…

No last mile problem, as in your autonomous vehicle will drive the last mile

Re: The Boring Company FAQ

#70

Post by JonRB »

flashman wrote: post #59
discodave wrote: post #48

The old strategy of hiding your outlandish claim in an assertion in the first sentence! "To solve the problem of soul-destroying traffic, roads must go 3D" The word "must" is a very strong one here, there are other options: * Reduce the amount of travel that people need to do (remote work, online shopping). * Reduce the density of cities (enabled by remote work or longer commutes with better internet access). * Incre…

The "problem of soul-destroying traffic" will exist for as long as driving remains the best all-round option. It's induced demand: build more roads > capacity increases > driving becomes easier > traffic increases until driving is as hard as it was. Add a congestion charge or tolls, and a proper public transport network. The solution is not more roads, it's fewer cars.

This worked really well in London, imo. Lots of really good transport infrastructure + city tolls make for a relatively nice driving experience.
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