That may be a lofty goal, but at least the message I got is that it is the one they want to reach.
Former tunnel boring engineer here.
There is a ton of room for innovation around tunnel boring machines built by the major manufacturers (primarily Herrenknecht and Robbins), around reliability, durability, ease of serviceability etc. I cannot emphasize enough how modern TBM's require an unbelievable amount of engineering attention, repair labor, spare parts infrastructure etc, similar to many super-early-stage fragile prototype technologies. Unfortunately TBM's are no longer early stage, but for some reason the technology is frozen at just-good-enough-to-barely-work."
However I don't know if the economics will work out to fix any of these. Here are a couple of the big problems:
* Most TBM's are semi- or fully-customized for a single job. This raises machine costs. It'd be better if there were only a small range of small-medium-large TBM's that work ~everywhere.
* Most TBM's are fully assembled in the factory, smoketested aka turned on to make sure they work, disassembled and shipped to the job, then reassembled and used. This is not efficient, surely we can figure out a better way.
* Most TBM's are entombed aka thrown away at the end of the job, because getting them out of the hole is expensive and difficult.
* Changing the cutterheads is labor intensive and dangerous and requires highly trained very expensive humans, and it's slow. While you change the cutterheads, your billion dollar toy is sitting there doing nothing.
* TBM architecture is highly dependent on geology. A slurry faced TBM that works in mixed soils is a totally different beast from a hard-rock TBM. It would be cool to have one machine that works in many geologies, perhaps with minimal or automated modifications.
* TBM's require lots of care and feeding from a small army of humans. This raises job costs.
* Topside support infrastructure such as slurry plants and ground freezing machinery comes from different vendors, often even from different countries. E.g. it's common to buy your topside slurry plant from the MS company, in France, while your ground freeze vendor might be Tachibana from Japan. Often each subsystem's engineers on site literally don't even speak a common language. Hilarity predictably ensues. Vertical integration would pay huge dividends here.
Ideally Elon can mass-produce TBM's that just work out of the box for most jobs, and that are easier to work on. Then we can laugh him out of town for his stupid "put cars in tunnels" ideas and use his miracle machines to build sensible train tunnels.
Here's Crossrail's video explaning how their TBMs work. This gives enough detail that you can get an understanding of what's going on.[1]
There's so much variation in geology. The Seikan tunnel to Hokkaido had huge variations in soil and the project went very slowly. Eurotunnel is mostly through chalk, and went well. The Gotthard Base Tunnel in Switzerland was a long grind through hard rock well above water level. That's a slow process, but was reasonably uniform. SF's BART tunnel, unusually, was built onshore in sections and lowered into a dredged trench. NYC's Water Tunnel #3 was in hard rock, and that project went very slowly.
Many things can go wrong. Hard rock may not be competent rock capable of supporting itself. The Tom Lantos tunnels south of San Francisco were through a small mountain of loose shale. One tunneling project in Japan hit an underground river.
The most advanced underground rail project today is probably the Tokyo-Osaka maglev line.[2] 43 kilometers of this is already operating, and most of the route is in tunnel. Tokyo to Nagoya is scheduled to open in 2027. The connection through to Osaka was scheduled for 2045, but the Government has decided to accelerate the program and get it done sooner. Here's what the ride looks like.[3] 500km/h. Working now.
[1] https://en.wikipedia.org/wiki/Ch%C5%AB%C5%8D_Shinkansen
They are often custom built (at least partly) and thus not mass produced. While we won't see that for rockets any time soon, it believe he managed to bring down the cost of building rockets and continues to do so (he uses his own money after all and does not have the support of every tax-paying citizen like NASA used to during the Apollo missions).
Sure the engineering challenges are probably different for the most part but the economics are the same. Rockets are more expensive then they should be. Boring is also more expensive then it needs to be.
> he uses his own money after all and does not have the support of every tax-paying citizen like NASA used to during the Apollo missions
This isn't really true. SpaceX, like pretty much all private Spaceflight providers, has received many development contracts from NASA. These are basically NASA giving the company a bucket of money to develop launch capabilities to certain requirements.
SpaceX has _absolutely_ been supported by the US taxpayer, and likely will continue to be. It definitely has been _much_ cheaper for the taxpayer than Apollo, but we haven't gotten a free lunch on this one.
They had to prove that they could do it before they saw a dime. The NASA has a project and gets funded without having at least a prove of concept (e.g. A single rocket that can do the job) as long as congress likes it. I'm not saying that this is bad, but this way he earned the money.
Furthermore, unlike the Apollo missions, sending satellites into orbit served a practical purpose. Sure the apollo missions were really cool and have helped science a lot but their practicality was a lot less.
I know Cincinnati's subway failed because of some bad tunnelling that caused foundations to sink .. well that and the great depression. If they had started earlier or designed it better, Cincinnati could have a Chicago like transit system today. Unfortunately it took them years to get a tram and there are people still trying to shut that down instead of expand it! Unbelievable.
I know in Seattle, many of the tunnels (like to Northgate/UDistrict) have actually been fully bored. The new stations are still not due to open for a few years, mostly because the majority of time isn't spend on the tunnels, but installing track, electrics and building the underground rail stations.
If Elon could make tunnelling 10x faster, requires much less Human labour and reusable, this will dramatically cut down the cost of building SubWay, or other underground Networks. I am not sure if such tech could be used to build like a underground Shopping Mall in Cities. But if we could build a Walk way under every Car Road would be great for urban cities.
I have a naïve question about subterrean _housing_.
With the real estate skyrocketing in some cities, and scarcity of terrain, I wonder why there is not much more underground liveable habitations (for example, near an expensive city center with no space left).
I think this is really just Elon's goal, and the talk and fluffy marketing video are just that. Fluffy marketing and PR for his companies.
Actually in some ways it bears a resemblance to the spaceflight industry (expensive, custom-made, few players). Coincidence?
Sending rockets to another solar system would be cheaper than the tunnels depicted in this video. I'm not even kidding.
Where is all that material going to go? There's so many tunnels there you could build a small mountain with it. Maybe he can team up with some sea-steading outfit and build a small continent off the shore of San Francisco.
You'd need three or four orders of magnitude reduction in tunnelling costs to make that anywhere near affordable, and even then you'd still have unbelievably complicated logistical issues. How much concrete do you need for those tunnels? What about ventilation? Safety procedures? Flood control? A single one of those could cost upwards of a billion dollars and I'm not sure there's a lot of cost savings by doing more of them, the complexities don't scale that way.
The more you dig, the more you're likely to hit something expensive you're going to have to pay to fix.
Musk's a sales technique to promise the moon (Mars really) and then use the cash to build a revolutionary but realistic company.
SpaceX isn't going to colonize mars, but its putting satellites in orbit.
As absolutely insane as his goals are, betting against him overall tends to be a losing bet. I'd be careful about what you think SpaceX "isn't" going to do. If it is technologically possible, they will do it. Period.
And X.Com didn't become Paypal. Paypal became Paypal. Paypal was already developed before the merger and it was not Musk's idea.
Next up: Elon's Space Elevator! Elon's Fusion Reactor! Elon's Teleporter!
(I'm kidding)
No, it's a hellacious mess of rocks of different types, of muck of all kinds, of brittle, water-filled pockets of who knows what, and every inch you dig you find out there's another problem up ahead.
In the case of Seattle they planned, they surveyed, they did test drilling, and they plotted a course that should have avoided everything, yet they still managed to slam into a steel pole that shouldn't have been there. It set their project back months, the machine was trashed and had to be dug up and fixed.
Plus, these tunnels are only part of the package. You need those surface access lifts, and those may well be the most logistically complicated of the whole system. To make this accessible you'll need hundreds of them, potentially thousands, and each one is a mega-project unto itself if you've sunk the tunnel down deep enough to avoid all those hazards you're now digging straight through.
The deeper you go, the more those lift stations cost. The shallower you go the more you'll come into conflict with infrastructure. There's no easy win here.
I'm pretty sure Elon Musk doesn't enter a market unless he intends to do just that.
Edit: I got downvoted a bit but it is his MO. He takes things that are expensive and makes them cheaper. For what it's worth though, I do think the tunnels in that video are ridiculous.
> And concrete production? And underground hazard detection? And coordination with city infrastructure? And...
to...
> And battery production, and driving hazard detection, and coordinating with the FAA and NASA, and rockets, and...
It's not guaranteed success (not even remotely) but if I had to bet on anyone...
You act like Musk does all the work himself. If he wanted to he could hire the best and brightest in each of those areas and they can work in parallel.
I don't even know if the guy is a good engineer. But I'm pretty sure to have the success he has had he knows how to inspire them.
But he might succeed at something somewhere in between the tunnel he is boring in his parking lot and the video.
Context: I lived in Boston during much of the Big Dig. Large tunnel projects scare the heck out of me as a tax payer.
If he retreats from this and builds some kind of pneumatic tube system to transport goods, people, or whatever, he still might have a chance of a win. Those systems have been proposed, and in some cases actually built, and in many cases they've been great ideas.
If he stubbornly insists on pursuing this batshit insane system of tubes he will fail, and he'll fail hard. There is not enough concrete in the world to make that many tunnels.
A rocket can go to the moon and come back safely, that takes an abundance of caution and significant attention to detail, but it's a fixed-length trip. Civil infrastructure has to exist for decades, or in the case of many American undertakings, well over a century. That requires extreme caution.
If you invented a concrete alternative today it'd take at least twenty years for it to be considered a viable alternative to concrete because long-term studies of the mechanical characteristics of it under a wide variety of conditions will have to be taken out.
Concrete is an extremely complicated material, I know people that have gotten a Ph.D. in aspects of it, and it's very well understood. This hypothetical alternative you're talking about has a lot to measure up to.
That's true. But techniques like compressed stabilized earth blocks can reduce the required percentage of concrete from ~30% to 4%.[1] For example, recently a 4% concrete and 8% ash CSEB was shown to be as strong as class 30 concrete.[2] Fly ash can also be used. Obviously considerations like longevity and manufacturability need to be validated, but the strength is there.
Essentially you're mechanically squeezing all the air out of the concrete, thus reducing the cement requirement. Since TBM tunnels are made from precast formed concrete currently, it seems like a natural cost (and CO2) saving improvement.
[1] https://www.researchgate.net/publication/267637559_Effect_Of...
And battery production? And crash test safety? And coordination with NHTSA?
He's cut component costs on the Tesla by maybe 70%. On the SpaceX project it's more like 80% compared to the highest cost competitor. Both of these are huge achievements.
The problem with tunnels is they're not cars, not rockets, not anything like he's ever done before. If he had a functioning Hyperloop system, if he'd proven he can build out infrastructure on a geographic scale and not just product from a factory I'd be more likely to agree with you.
This is a bad idea, a bad project, and a total waste of time.
If, by some stroke of genius and fluke of luck, this thing does get built it will go down in history as the most absurd thing ever constructed.
Then perhaps a hundred years after it goes bankrupt someone will be drilling down there and hit a tunnel that nobody knew existed and re-discover its brief and absurd history just like Chicago has done with their own boring company: https://en.wikipedia.org/wiki/Chicago_Tunnel_Company
Your phrasing is interesting given that SpaceX announced sending two people around the moon next year.
http://www.spacex.com/news/2017/02/27/spacex-send-privately-...
So I suppose my above was wrong. I'd guess the more reliable enablers are only sufficient density, coupled with good geology and a cooperating regulatory / permitting structure.
Not sure what the geology of San Francisco / California tends to be like, but I believe most of the Manhattan skyscrapers are anchored down to the bedrock. Which I'd expect would require cutting and reinforcing vs just "drill on through".
(which were during construction, but happened in "finished" sections, I believe. NATM applies a single pass of shotcrete to the cut rock surface)
He's going to involve the government? :|
I wonder if anyone has tried that yet?
And, hell, the fact that many cities aren't built on rock (e.g., London, Berlin, Moscow), so even if you can bore through solid rock you're probably not actually that well off: can you also bore through clay and gravel?
Good luck, Elon. It'll be another moonshot company if you can pull it off.