Comment by loufe
9 years ago
The costs of tunneling are like FAR more expensive than most think. Breaking, excavating, and supporting rock is slow, time and cost heavy, and precarious work. While this is an interesting concept, unless there are serious advances in rock boring techniques (personal opinion: there are none coming) this will never approach fruition. I would suggest anyone interested in further research look into the "Big Dig" of Boston and the staggering costs and challenges it faced.
Good luck, Elon. It'll be another moonshot company if you can pull it off.
That's the entire point of The Boring Company. It's way more expensive than anyone expects. That's the problem they are trying to solve. The entire goal is "serious advances in rock boring techniques".
That may be a lofty goal, but at least the message I got is that it is the one they want to reach.
>> "(personal opinion: there are none coming)"
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.
Now that's a useful comment.
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
[2] https://www.youtube.com/watch?v=z38JIqGDZVU
[3] https://www.youtube.com/watch?v=ltqp4McM2wY
So they are somewhat similar to the problems Elon tries to solve with rockets. Rockets are not normally reused, which makes them expensive to use.
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.
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I really wish this was a top-level comment so it could be voted up to the very top. More informed than 99% of this entire comments section. Thank you!
That's a lot of good insight into tunnel boring. Thanks for that.
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.
Precisely this. Most people are focusing on the wrong issues, whether it should be tunnelling cars and not Subway trains etc. That is like arguing SpaceX is putting humans on Rocket and not Satellite.
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.
Fantastic post, thanks.
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).
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Very interesting. Your comment should seriously be at the top.
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.
It seems to me that there may be room for disruption. Currently every TBM (tunnel boring machine) is completely bespoke and is used for exactly one project and is then dismantled/recycled. They cost hundreds of millions of dollars each. I imagine there are relatively few manufacturers out there building TBMs.
Actually in some ways it bears a resemblance to the spaceflight industry (expensive, custom-made, few players). Coincidence?
Seattle's Bigger Dig is also worth studying: https://en.wikipedia.org/wiki/Alaskan_Way_Viaduct_replacemen...
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.
Somehow I think Elon Musk has made it through the middlebrow dismissal phase of this if the concept has made it this far(to include actual digging in SpaceX's parking lot even).
Musk could also be bullshitting to help get funding to create a boring machine that is just twice as good as what we have now. That would be a very profitable company and would reduce subway costs, etc.
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.
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Somehow I think Elon, who's a pretty smart guy, has run out of challenges and is now resorting to trying crazier and crazier things.
Next up: Elon's Space Elevator! Elon's Fusion Reactor! Elon's Teleporter!
Make an underground concrete factory in the tunnel system and use the tunnel material to make concrete to make the tunnels.
(I'm kidding)
Loose dirt off of the coast of SF? That doesn't work so well in an earthquake. Lookup "liquefaction".
If you start the tunnel down far enough, you could be below anything that could be hit. Would that make it less expensive?
You make it sound like all that's down there is uniform layers of perfectly intact rock just waiting to be bored.
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.
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> unless there are serious advances in rock boring techniques
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...
You could change...
> 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.
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Honestly though these same sentences came up around Teslas too.
And battery production? And crash test safety? And coordination with NHTSA?
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> It'll be another moonshot company if you can pull it off.
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-...
Anyone know what it's costing Tokyo Mwtro to keep digging tunnels at very large depths? They have great coverage yet they're still digging new lines.
The issue with Tokyo is that the density supports metro expansions.
Per distance costs should be theoretically comparable? (Regulation costs and labor coming to mind as drivers of cost differences)
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Not only the drilling, but the shoring up and walling of the tunnel. Also, people tend to be opposed to "move fast and break things" if they're likely to get buried under them.
Until you remove the "they" by fully automating the system.
People also tend to object to "move fast and break things" when they, and their very expensive buildings, are on top of said things and get broken as a result.
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Ultimately you want to put passengers in the tunnel, yes?
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Elon has stated that he believes it is possible to reduce tunnel creation speeds by 5 to 10 times, and that this is what they will work on doing:
https://youtu.be/FPzpugrbwBE?t=120
possible to reduce tunnel creation speeds by 5 to 10 times
He's going to involve the government? :|
Maybe one day we could connect the individual pods, and even gasp route these "coupled cars" on rails above ground.
I wonder if anyone has tried that yet?
That would be amazing! I wonder if car manufacturers wouldn't oppose it through some sneaky moves though...
Above ground rail isn't practical in urban areas. The video had silly car tunnels, but in practice, I'm sure the bulk of their business will be subway tunnels.
What? The Chicago L and NYC subways (both of which carry hundreds of millions of riders per year) have many, many miles of either at-grade or above-grade track.
"unless there are serious advances" ...which is precisely what Musk is researching (bottleneck of boring machines): “We’re trying to dramatically increase the tunneling speed,” Musk says. “We want to know what it would take to get to a mile a week? Could it be possible?” See https://www.bloomberg.com/news/features/2017-02-16/elon-musk...
AFAIK, in many major cities, a major part of the cost of tunnelling is the fact we simply don't know where hundred-year old utilities are.
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?
The whole process can be fully robotized, and the energy comes from cheap solar. It's not even a moonshot, it will happen. We will do even crazier things than this. In the future we will bore tunnels out of boredom.