19 ms·

Tunnel Boring Machines (2018)

313 points by luu 7y ago

spectramax 7y ago
There is a quality about TBMs which vaguely reminds me of the feeling of getting a new LEGO set and building stuff. Imagine if we had cheap ways to build tunnels, no more traffic, no more congestion, roads and parking lots would only exist underground and cities would have more space for gardens, parks, buildings, and walkways. We have these things - Subways but its very expensive to build that system. Elon has an itch to solve this problem and I want this dream to succeed! While that's going on, please someone make a game out of building tunnels, it would be super cool!
- djsumdog 7y ago
  The article clearly states we have the tunnel tech. That's not the issue. We already have the tech to connect a lot of American cities with decent trains again. It's about buy-in from the communities, the ability to put up stations (safely, faster, more efficiently) and Americans to stop screaming "our spaces are too far apart." They weren't less than 100 years ago. They will collapse back in once we start building transport again. As shown in the article, the current tech is really good. It just takes time and the biggest problem are the stations, track and power. These car tubes that Elon is proposing are terrible. We need a faster way to put up full metro systems.
  - sansnomme 7y ago
    Perhaps it has nothing to do with tech, but framing it as a tech problem lends credibility and allows for easier structural changes/violence. It is easy to say "here's how to improve transportation because xyz is a tech issue" than to say "we have a NIMBY and willpower problem, let's hire some political grads to draft a plan on lobbying politicans and researching the impact of solution abc", especially when your past achievements are all tech related. Also tech has the perception of being hard, inflexible. Just ask anyone who had to contact Google for customer support. Tech billionaires are not known to be easy to sue either, at least compared to a bunch of city-council bureaucrats. See the first paragraph of this article as an example of how tech CEOs are portrayed in the media versus city government bureaucrats: https://www.wired.com/2017/05/apple-park-new-silicon-valley-campus/ https://www.wired.com/2017/05/apple-park-new-silicon-valley-... Framing it as a people problem is simply asking for interference by third-party interests, which is one of the main factors currently preventing accumulation of sufficient political willpower to build metros. It may be a cheap, unethical hack in the sense that the state avoids having to exhaust political capital/use controversial powers like eminent domain in exchange for having private interests build poorly thought out transportation infrastructure. At the end of the day there is an unfulfilled need for transportation infrastructure. A poorly thought out one is still better than nothing.
- chrispeel 7y ago
  So, replace every major road in big cities with a park or green space over a tunnel? I like this vision :-)
- cwojno 7y ago
  Building more capacity usually induces demand: https://en.wikipedia.org/wiki/Induced_demand https://en.wikipedia.org/wiki/Induced_demand I know it's boring (derpa derpa), but adding congestion pricing, mass transit is likely a better option. https://ideas.repec.org/b/mtp/titles/0262012197.html https://ideas.repec.org/b/mtp/titles/0262012197.html Getting rid of cars should be the goal, not encouraging them: https://books.google.com/books?hl=en&lr=&id=pjatbiavDZYC&oi=fnd&pg=PR13&dq=automobile+traffic+reduction&ots=BbOToLpEzB&sig=A6266ARbk19JuRygzwjPkGuU2ic#v=onepage&q=automobile%20traffic%20reduction&f=false https://books.google.com/books?hl=en&lr=&id=pjatbiavDZYC&oi=... Or, skipping the commute altogether with remote work.
  - wongarsu 7y ago
    > Building more capacity usually induces demand Viewed from a different perspective: we have so little capacity that most journeys are never taken. I agree that in general mass transit is much better than cars. But tunnels do remove many of the arguments against cars: pollution (both CO2 and tire abrasion) can be easily filtered, noise is blocked by solid rock, tunnels can be crossed without knowing they are there, they don't interfere with pedestrians, don't reduce building density, don't create artificial barriers. Cars are still incredibly dangerous, but Elon's sledges would solve even that. Cars still take up a lot or room both in transit and when parked, but most other disadvantages are reduced or eliminated by putting them in tunnels.
    - legulere 7y ago
      People will just start commuting to further away places like from barcelona to london: https://www.theguardian.com/cities/2015/aug/11/commuting-from-barcelona-a-london-worker-who-makes-it-pay https://www.theguardian.com/cities/2015/aug/11/commuting-fro... You can argue for an economical benefit, but it's very hard to argue that they are larger than the costs.
    - bluGill 7y ago
      Elon's tunnels don't solve anything. His cars are so large that the amount of people a tunnel can move is small. We can add more tunnels, but it isn't cheap, and geometry means we can't add enough - there is only so much space below us and you need to keep tunnels apart.
- bArray 7y ago
  > Imagine if we had cheap ways to build tunnels, no more > traffic, no more congestion, roads and parking lots would > only exist underground and cities would have more space > for gardens, parks, buildings, and walkways. Or, skip the tunnel building and just ban cars from major cities. Building more infrastructure to "reduce traffic" only makes using vehicles more attractive. The amount of congestion is approximately equal to the amount of congestion the average person using the infrastructure is willing to accept, so making it less congested just means more people use the infrastructure until the limit is reached again. The real answer to the problem is to simply ban all but buses and delivery vehicles - even then you can incentivize that they are electrically driven. Space increases and infrastructure maintenance costs are reduced, not increased. The real golden use for TBMs is for efficiency - i.e. Go around some mountain or go straight through it? Go around a city or go under it? I imagine buildings sharing a service elevator down to the tunnel where delivery vehicles can offload to and send goods up (rather than Musk's idea of trying to lift a several tonne vehicle in some personal elevator). Would likely make sense for all kinds of maintenance this way to, servicing water/gas pipes or electricity/internet lines for example could be as simple as removing a service panel from the side of a tunnel, rather than the terrible solution we have today involving digging up streets over and over.
  - rklaehn 7y ago
    Why have technical innovation at all, let's just outlaw stuff... I really don't get this desire to outlaw cars. I like walkable cities, but I also like the comfort and privacy of car transport. I live in a place (Germany) with good public transport. I used to live in cities with very good public transport. I still don't enjoy being squeezed in with thousands of other people. Does that mean that people like me have to be reeducated and/or forced to see the error of their ways?
    - giomasce 7y ago
      I don't think that outlawing car is a solution, but disincentivizing them maybe is: higher taxes with which pay a better public transport network, less and more expensive parking, more lanes dedicated to public or unmotorized transport, traffic lights more favourable to public or unmotorized transport, stronger presumption of fault on the side of the motorized vehicle after accidents. All of these improve the value of less impacting transport. After all, cars, especially when moving just one person, heavily overuse shared and scarce resources like space and environment. It's all too fair that they pay a higher share to public resources. Maybe you will still use your car, accepting to pay a higher price for it, but other people will switch, making the world a better place also for you.
- jtolmar 7y ago
  You could replace highways with a magical teleporter and you'd still have traffic and congestion. Most traffic happens at the interface between the highway and the rest of the road network, as cars can only join the flow of traffic at whatever rate its capacity frees up - and cars entering the city compete for that capacity with cars leaving parking spots. Cities are already crammed full of street capacity, so the only way to increase capacity is to increase the number of people per car. And that solution, taken to its logical conclusion, is a train. Subways face similar problems to highway interchanges - passengers have to rejoin the flow of (foot) traffic. This is easier than with cars, since people are smaller and most of them can use stairs, but the cost of stations ends up being the larger portion of cost, not the cost of tunnels (which can be built more cheaply using cut & cover than they can with boring machines anyway). I'd like to see Musk throw his resources behind cheaper ways to make stations, instead of a problem that's better solved by digging a ditch.
- TeMPOraL 7y ago
  > While that's going on, please someone make a game out of building tunnels, it would be super cool! In a way, Minecraft is that game. At least when I played it couple years ago, I spent most of my time building metro tunnels.
baddox 7y ago
These animations are great, but for some puzzling reason they only advance while I am scrolling the page. To watch an animation I have to hold my thumb on the screen and subtly scroll up and down. This is on an iPhone X.
- dingo_bat 7y ago
  Works perfectly on Firefox, Android 10, Galaxy S10.
asdff 7y ago
Is there a reason why cut and cover isn't used very much these days, apart from mild disruption to car traffic?
- jcims 7y ago
  Utilities?
- bskap 7y ago
  Most of these tunnels are being built in heavily populated areas where surface space is at a premium. You'd have to tear down thousands of apartments and offices to make any meaningful progress on a cut and cover tunnel inside a city unless the tunnel is exactly following existing roads. That would be both very expensive and far more disruptive than just a little traffic
  - afterburner 7y ago
    > unless the tunnel is exactly following existing roads I mean, a lot of subway projects are specifically planned to follow a main road simply because cut and cover is cheaper.
- ant6n 7y ago
  There seems to be a low tolerance to the construction disruption, especially to adjacent businesses and residents. Cut and cover also had high cost of moving infrastructure. I also wonder whether there's some relationship with the speed of construction - in NYC, ripping up the whole street to build a Subway was perhaps more acceptable if it's done in a year or so. One note: new cut and cover projects tend to actually use cover and cut: first the walls are built underground (often piledriven), then the top is covered with a concrete plate, then the Earth dug away from below. This minimizes the surface disruption.
- KaiserPro 7y ago
  it is ridiculously labour intensive. First, all utilities have to be mapped out, then any basements shored up. Then once the cut and cover is in progress, all utilities have to be re-routed, during, then replaced after the tunnel is cut. Then, the disruption of having major transit ways shut for n weeks. Lastly, there isnt a machine to do it. The TBM is pretty efficient labour wise.
spullara 7y ago
Or you could just move the surface streets a couple of stories up like they did in the early 20th century in Chicago. Trucks (for deliveries, etc) are not allowed on the surface, only below.
- djsumdog 7y ago
  A lot of early cities jacked up their buildings. Chattanooga did due to flooding. I somehow doubt such things could happen today considering the superstructure foundations under a lot of our modern buildings.
  - spullara 7y ago
    Definitely easier to keep the buildings at their current level and just make a new entrance on the second (or higher) floor.
    - deleted 7y ago
      [deleted]
    - lmm 7y ago
      You can't bootstrap having a nice walking environment at above-ground level that way. Who's going to open the first cafe where there's no foot traffic? Why will anyone spend a lot of money on entrances that no-one's going to walk to? What pedestrian is going to want to keep walking up and down stairs while the network is partially complete. The City of London tried to do what you're suggesting and it was a total failure, because while it might have worked if it could have magically all been done in one go, there's no way to get to there from here.
  - cududa 7y ago
    The only time cities have jacked themselves up is after fire or natural disaster. No way “underground deliveries” is scalable.
dlgeek 7y ago
Side note: Missed opportunity for the title "Interesting Boring Machines"
- ant6n 7y ago
  Actual title of article: "Far From Boring: Meet the Most Interesting Tunnel Boring Machines"
sytelus 7y ago
Here's interesting tidbit: Vast majority of underground railway network in Moscow was built in 1950s. Cost of building a mile of interstate highway in US is about $5M. Interestingly this cost hasn't changed since 1956 in inflation adjusted dollars when new 41,000 miles of interstate highway in US was laid out. It seems major cost is not tech but quite possibly regulation and/or government inefficiency/corruption.
- wongarsu 7y ago
  We have also use highways a lot more and accordingly require better construction. I'm not saying nothing interesting is going on, but construction+maintenance over 20 years, adjusted for vehicle miles traveled (or rather semi-truck-miles traveled) would be a much better indicator.
pugworthy 7y ago
I'm not out to analyze the clearly knowledgeable content of this article, but I'd not be surprised if someone wrote something just like it when he (Musk) started the whole illogical "make a rocket come back and land" stuff. It's not logical, but I'm giving him the benefit of the doubt. Let him do his thing. Who knows?
- greglindahl 7y ago
  One odd thing is the claim that it's just as cheap to bore a much larger tunnel. Yet no one is bidding a much larger tunnel boring price anywhere close for either the short Las Vegas tunnel or the much longer Chicago one.
  - newyankee 7y ago
    It is not odd i think it is a thinly disguised lie. If it was serious it would've done a point by point rebuttal of Elon's proposals and why he think he can reduce the cost more than 10x for same capacity (capacity is the operative word). At the very least it could've shown cost calculations for these tunnels. If they are as attractive as portrayed we would've had many more of them.
    - Gibbon1 7y ago
      Calculate the diameter of two small tunnels that can carry a lane of traffic vs one that can carry two lanes. Single lane, 12 feet wide, 12 feet tall. Requires a tube 17 feet in diameter. Or 54.3 feet circumference. Two of those is then 108.6 feet. A tube that can carry two lanes, 12X2 = 24 feet. Diameter is 26.8 feet or 84.3 ft circumference.
      - superice 7y ago
        Except that in tunnel boring the circumference is not that relevant, it's the surface area of the cross section of your tunnel. In the first instance that's 113.1 square feet, in the second it's 452.4. Every time the radius doubles, the surface area quadruples. The perfect tunnel transports people horizontally in a very narrow tube.
tiku 7y ago
Why can't we just vaporise stone with lasers..
- Animats 7y ago
  It's been proposed. By Disney. 1958. [1] https://youtu.be/TwA7c_rNbJE?t=137 https://youtu.be/TwA7c_rNbJE?t=137
  - dr_dshiv 7y ago
    My favourite video of all time.
  - dredmorbius 7y ago
    The success rate of those predictions is ... low. At 60+ years, only a couple are commonplace or in effect, mostly the inducement of sprawl. Virtually all the rest assume vast amounts of free power which never materialised. The automation examples are only now, and with great difficulty and challenges, appearing. Litho-annealing / vitrification remains a fantasy. Lasers serve as alignment aids, not boring mecganisms. Any idea who commissioned/ contributed to this?
- wongarsu 7y ago
  The boiling point of limestone is around 825°C or 1515°F. Heating up a tube of multiple meters diameter and multiple kilometer length to that temperature would require insane amounts of energy. A laser makes it possible to efficiently heat a small spot to that temperature which helps reduce waste heat, but you still have to heat every spot at some point.
  - polemic 7y ago
    I wonder what you do with a jet of vapourized rock too, once you've got it to that temperature!
    - lstodd 7y ago
      Well I guess one can suck the plasma into a condenser unit and then on to a conveyor belt for extraction. Now what you do when those lasers hit a high-water-content sediment and cause a vapor explosion, loss of integrity of surrounding rock and flooding?
Animats 7y ago
Musk could help with the back end of the problem. The TBM up front gets all the attention. Behind the TBM is usually a temporary two-track narrow gauge railway line, with muck cars carrying dirt and rock out, segment cars carrying tunnel wall segments forward, plus tool cars and worker cars now and then.[1] Hanging off the back of the TBM is all the machinery to move all those heavy items around.[2] Including the machinery for laying more railroad track behind the TBM. Self-driving electric muck cars, segment cars, etc, might replace that temporary rail infrastructure. That's something Musk's company could address. The back end of the process seems to get less attention than the front end. Most of the length of the TBM is devoted to material handling, though, as is the rest of the tunnel all the way back to the entry. A big fraction of the cost is in moving all that stuff around. [1] http://www.zslocomotive.com/products http://www.zslocomotive.com/products [2] https://youtu.be/SY3Q9GqUYro?t=115 https://youtu.be/SY3Q9GqUYro?t=115
newnewpdro 7y ago
The vertical shaft sinking machine process is basically just an automated form of the old-school manual method of digging a well with men and shovels. Laborers excavate at the bottom while new bricks are laid incrementally forming the casing at the top. The whole column of bricks slides down as a cylinder whenever progress is made at the bottom. I've long wanted to dig a well that way, it's gotta be surreal to be at the bottom digging away with a little shovel and seeing a towering column of bricks move as one to fill in the progress. It can't be terribly safe :)
- jaclaz 7y ago
  >The vertical shaft sinking machine process is basically just an automated form of the old-school manual method of digging a well with men and shovels. Yes, and the whole staff seems a lot more theorical than the rest, the approach can only work in a subset of terrains and for relatively short shafts (if you exceed certain lengths or in many terrains the attrition between the shaft walls and terrain will stop the sinking). Usually in tunneling projects ventilation shafts are dug "traditionally" (if rather short) or by "raise boring" (if longish). Some related videos: https://www.youtube.com/watch?v=V2oWTk4khvg https://www.youtube.com/watch?v=V2oWTk4khvg https://www.youtube.com/watch?v=6QueB4GCQww https://www.youtube.com/watch?v=6QueB4GCQww
- KaiserPro 7y ago
  the "vanilla" TBM is an automated version of this: https://en.wikipedia.org/wiki/Tunnelling_shield#/media/File:Thames_tunnel_shield.png https://en.wikipedia.org/wiki/Tunnelling_shield#/media/File:... just with prepoured concrete blocks instead of bricks.
- lstodd 7y ago
  Here's an absolutely insane guy's channel https://www.youtube.com/channel/UCti7FZiCHC5fhvgN_Ns_5ew https://www.youtube.com/channel/UCti7FZiCHC5fhvgN_Ns_5ew He digs wells by hand. Very scary videos.
  - goatsi 7y ago
    There we go: https://youtu.be/5-j-EHXhBh8?t=465 https://youtu.be/5-j-EHXhBh8?t=465
lazysheepherd 7y ago
Article does not seem to understand what Booring Company trying to achieve. It does not even seem try to understand. We all know it's very popular to love Elon Musk. But it's generally more attractive to one-up those who do and hate Elon and his "fans". As a disclaimer: I am in the wagon of "please leave this guy alone so he can do his thing, whatever it might turn out to be". And I do not see any value in this article. Booring Co. is about creating rich network of very small tunnels _to solve urban traffic,_ whereas article only talks about creating huge tunnels for longer distance transportation. Article seem to be making a comparison while things it compares aren't in the same category nor does they try to solve the same problem to begin with. Incoherent and poorly thought-out", if not straight clickbait.
- projektfu 7y ago
  The article only briefly mentions the Boring company and Elon Musk, because it's mainly about how cool these large tunnel are and how the machines are large enough to allow multimodal transportation in a tunnel. The comparison to Musk is that his company is making a bet the rest of the industry has rejected. They are all building large, versatile tunnels. Musk is betting that small tunnels will be the future. Who knows? What I got out of the article was definitely not an "anti-Musk" vibe. Not even super critical of the Boring company approach. It was more of a "modern marvels" type of article.
k_sze 7y ago
Is Elon Musk a Samuel Beckett fan? I can totally picture a city council asking what's taking a tunnel project so long to complete, and Musk answering, with a straight face, "Oh, we're just waiting for Godot."
rmason 7y ago
I'm not sure that I agree with the author on Elon Musk's tunneling ambitions. Far more people are betting against him on Tesla and SpaceX without much success. One thing lost in the debate is if the costs are lowered it will also increase the number of cities where a subway is possible financially. I see cities spending huge money on dedicated bus lanes. The bus companies adore it but I'm pretty certain that the return on investment is abysmal. They tried to implement it locally and the grass roots groups put up such a huge fight the politicians withdrew support for it. As far as the cost of the stations I wonder if anyone has given thought to using 3D concrete printing? Admittedly it would be easier if you excavated from the surface as opposed to widening a tunnel but I still think it has the possibility of losing costs. https://all3dp.com/2/concrete-3d-printing-how-to-do-it-and-applic https://all3dp.com/2/concrete-3d-printing-how-to-do-it-and-a...
- walkingolof 7y ago
  "Musk says he can build tunnels cheaper if he just makes them smaller. But in reality, it’s not small TBMs that are the future, but big ones. The cost of a TBM doesn’t get much higher as you increase its diameter. Tt is therefore cheaper to build one very large tunnel, rather than two smaller ones." If that is true, then Elon is betting on the wrong horse.
  - rmason 7y ago
    I can remember articles promoting hydrogen powered cars as the future. They even said Elon made the wrong bet with electric. Some company's are still hawking hydrogen as the future, the difference is no one is paying any attention to them any longer. Someone else has made the bet for bigger tunnels and they're using a PR agency to push back. PG called out this tactic a few years back: http://www.paulgraham.com/submarine.html http://www.paulgraham.com/submarine.html
    - bluGill 7y ago
      The bigger tunnel people have proven success, while the small tunnel people just have hype. People shut up about electric cars over hydrogen when electric proved itself. Note that back when this started there were many hydrogen naysayers who pointed out all the problems the hydrogen proponents have faced. The electric car people got lucky that lithium batteries advanced to where they could work - 20 years ago this wasn't a given to battery experts.
topmonk 7y ago
I know this is probably a very stupid idea, but I was thinking what if we shot ourselves out of rail guns into the air into a bullet shaped craft with fins? You could be shot out of one rail gun in San Francisco, glide for awhile, fall to the earth and caught by a “reverse” railgun in San Jose. It'd be cheaper and safer than planes since no need to carry fuel or an engine on board, and could have an emergency parachute incase something went wrong. Or maybe I've been dreaming about Kerbal Space Program projects too much lately. (I'm fully expecting to be flamed and jided for this)
- rkangel 7y ago
  It's a fun idea, but G-Force makes it unusable for people. The speed to which you'd have to get, over the length of the barrel would make it unsurvivable, or at least very unpleasant.
- arethuza 7y ago
  This sounds like a failure mode for Hyperloop. Edit: Also reminds me of a rather entertaining failure mode for UK AGR nuclear plants - but that's another story.
- tim333 7y ago
  Not so sure about the "safer than planes" - planes are pretty safe really. Also I think the initial acceleration would be uncomfortable for passengers if they somehow retained consciousness. Edit - the US navy rail gun apparently produces 60,000 G, humans black out around 10. You might just about be able to do SF to San Jose with a glider and winch launch if they improved the tech 3x or so. Longer cable etc.
  - Retric 7y ago
    Time is a major component of g force tolerance. Healthily people can take 15g’s for short periods without issue, but extend that to a minute and it can prove deadly. In ideal conditions linear acceleration to Mach 2 at 5, 10, even 20g is fine. But, if you want to go much faster the limits are reduced significantly. The Soyuz for example can hit 8.5g’s for about 60 seconds in some situations which adds up to ~Mach 14.6 and is a rather extreme situation.
morekozhambu 7y ago
> Rather than including a facility for assembling the tunnel lining (out of multiple segments) inside the TBM, complete rings are inserted at the insertion shaft, and the whole tunnel is jacked forward one segment at a time. This seems inefficient.
- bluGill 7y ago
  Looks to me like they are looking at only going a short distance. I doubt you could get more than 100 meters like that, but if you only need 100 meters of tunnel it is probably cheaper because it is faster.
choeger 7y ago
I think one of the major causes for the high cost of tunneling is that it is done too seldom. Any major city in the world probably has room for 10 or so additional tunnels, so why do they not operate a fleet of TBMs constantly for the next n years?
ksec 7y ago
I have many questions, 1. Are any of these TBM considered state of art? I dont see any tech inside those TBM that could not be done 10 years ago other than the cost of the machine. We are entering new Space Race era and yet some fundamental stuff still looks very, should I say "traditional". 2. Why cant we build even bigger TBM? Like Double the current diameter. Or Bigger TBM that are Rectangular rather than Circle. 3. The biggest problem with TBM is that they are slow. Even if we had made them 10 times faster I would still consider them very slow. Surely there could be technology that improve on it? 4. Are there any reason why we dont use TBM for small pipes, ( like for electricity or fibre optics, )
- sjwright 7y ago
  TBMs can only go as quickly as you can shift earth out of the tunnel. Increasing the diameter hugely increases the volume of earth. If you want to excavate a rectangular tunnel, you want a roadheader. https://en.wikipedia.org/wiki/Roadheader https://en.wikipedia.org/wiki/Roadheader
  - bobbydroptables 7y ago
    Increasing the diameter proportionally increases the exit pathway through which you can shift earth out of the tunnel. Obviously there are complexities in the field that I'm not aware of but these seem like problems you can engineer around. It's really surprising to me that in 2019 the limiting factor in a billion/trillion dollars industry like transit is something that could be solved with a better conveyer belt. To ask OP's question another way: many areas of technology and engineering have improved rapidly over the last decade or three. Have TBMs been keeping up?
    - sjwright 7y ago
      Increasing the width of the exit pathway doesn't increase the rate at which you can deal with the mountain of crap piling up at the end of the tunnel. You sound like Elon Musk. "This problem seems easy. Clearly all existing TBMs suck so we'll just build a better TBM!"
- 7y ago
LargoLasskhyfv 7y ago
I'm uninpressed because it lacks Nuclear Tunnel Boring Machines like in [1] and [2] as envisioned by [3] for [4] and [5] in 1972 and 1978. Which all Hyperloop afficionados should read, if they haven't done so already :-) [1] https://patents.google.com/patent/US3693731 https://patents.google.com/patent/US3693731 (I'm wondering about steam explosions when hitting ground water, which is not unheard of. But...NUKULAR!) [2] https://en.wikipedia.org/wiki/Subterrene https://en.wikipedia.org/wiki/Subterrene [3] https://en.wikipedia.org/wiki/Robert_M._Salter https://en.wikipedia.org/wiki/Robert_M._Salter [4] https://www.rand.org/pubs/papers/P4874.html https://www.rand.org/pubs/papers/P4874.html [5] https://www.rand.org/pubs/papers/P6092.html https://www.rand.org/pubs/papers/P6092.html (Lacking cheaply mass produced super-conductors here)
vpribish 7y ago
"The cost of a TBM doesn’t get much higher as you increase its diameter." This is the key assertion, and it is unsupported. - heat extraction will become a bigger problem - debris extraction too - cost of parts, cost and speed of logistics like transport and installation of the machine will be worse - small number of exotic large TBMs will scale worse than large number of small TBMs in manufacturing cost and operating experience - I've seen elsewhere (citation missing) that small borers move much faster than large so any costs that scale with time will be worse. - risk-wise: a portfolio of small borers will have less risk than an all-eggs-in-one-basket gamble. a broken part delaying a big machine incurs more cost than ona smaller machine. unless your project requires a single enormous bore I think you would prefer to use the smallest you can get away with. The author does not seem to have any relevant experience, so I'm not going to take this on his authority; he's a programmer who has done scheduling software on metro projects and is working on an MBA. Interesting summary of types of machines though!
- astrodust 7y ago
  Key word "much".
teslaberry 7y ago
boring tunnels is dumb. ground shifts, and more importantly , there is hydrology as a problem. the right approach is the opposite to 'boring'. driving pylons into earth to make it even more rock hard if it isn't already bedrock. then you build UP AND IN 3 DIMENSIONS. the problem is not that we cannot dig. the problem is that we have no mastered 3dimensional building. what many people don't get is that a very large part of our technical deficiencies in this regard , result from a lack of investement in specific construction technologies becuase of a root problem in THE LAW. the legal system has dramatically languished in the face of new potential technicailities. instead, it has continued to support a 2 dimensional 'foot print' system, and an anachronistic 'air rights' system of strict property law has then been layered on top of it to enable rights to build 'up' to a point. right now , it's easy and cheap to build up to 100 meters. relatively . building higher is stupid and unnecessary, building lower is lazy and even dumber. the cities of the future(s) don't ahve better cheaper tunnels under them, but bettter cheaper 'tunnels' going through out them. above ground. rather these tunnels would be considered 'rights of way' and the legal frameworks around them would be complex, but enabling, rather than what we have now, a legacy system impeding progress. other than water and steam mains and natural gas mains, which carry extremely heavy water, there is almost NOTHING you cannot put under above ground inside a building. nothing. there is NO reason to have a 'subway' made out of giant metal things weighing insane amounts of weight. just build this thing together. nothing is going to stop us....now or later.

313 points by luu 7y ago

There is a quality about TBMs which vaguely reminds me of the feeling of getting a new LEGO set and building stuff. Imagine if we had cheap ways to build tunnels, no more traffic, no more congestion, roads and parking lots would only exist underground and cities would have more space for gardens, parks, buildings, and walkways. We have these things - Subways but its very expensive to build that system. Elon has an itch to solve this problem and I want this dream to succeed! While that's going on, please someone make a game out of building tunnels, it would be super cool!

djsumdog 7y ago
The article clearly states we have the tunnel tech. That's not the issue. We already have the tech to connect a lot of American cities with decent trains again. It's about buy-in from the communities, the ability to put up stations (safely, faster, more efficiently) and Americans to stop screaming "our spaces are too far apart." They weren't less than 100 years ago. They will collapse back in once we start building transport again. As shown in the article, the current tech is really good. It just takes time and the biggest problem are the stations, track and power. These car tubes that Elon is proposing are terrible. We need a faster way to put up full metro systems.
- sansnomme 7y ago
  Perhaps it has nothing to do with tech, but framing it as a tech problem lends credibility and allows for easier structural changes/violence. It is easy to say "here's how to improve transportation because xyz is a tech issue" than to say "we have a NIMBY and willpower problem, let's hire some political grads to draft a plan on lobbying politicans and researching the impact of solution abc", especially when your past achievements are all tech related. Also tech has the perception of being hard, inflexible. Just ask anyone who had to contact Google for customer support. Tech billionaires are not known to be easy to sue either, at least compared to a bunch of city-council bureaucrats. See the first paragraph of this article as an example of how tech CEOs are portrayed in the media versus city government bureaucrats: https://www.wired.com/2017/05/apple-park-new-silicon-valley-campus/ https://www.wired.com/2017/05/apple-park-new-silicon-valley-... Framing it as a people problem is simply asking for interference by third-party interests, which is one of the main factors currently preventing accumulation of sufficient political willpower to build metros. It may be a cheap, unethical hack in the sense that the state avoids having to exhaust political capital/use controversial powers like eminent domain in exchange for having private interests build poorly thought out transportation infrastructure. At the end of the day there is an unfulfilled need for transportation infrastructure. A poorly thought out one is still better than nothing.
chrispeel 7y ago
So, replace every major road in big cities with a park or green space over a tunnel? I like this vision :-)
cwojno 7y ago
Building more capacity usually induces demand: https://en.wikipedia.org/wiki/Induced_demand https://en.wikipedia.org/wiki/Induced_demand I know it's boring (derpa derpa), but adding congestion pricing, mass transit is likely a better option. https://ideas.repec.org/b/mtp/titles/0262012197.html https://ideas.repec.org/b/mtp/titles/0262012197.html Getting rid of cars should be the goal, not encouraging them: https://books.google.com/books?hl=en&lr=&id=pjatbiavDZYC&oi=fnd&pg=PR13&dq=automobile+traffic+reduction&ots=BbOToLpEzB&sig=A6266ARbk19JuRygzwjPkGuU2ic#v=onepage&q=automobile%20traffic%20reduction&f=false https://books.google.com/books?hl=en&lr=&id=pjatbiavDZYC&oi=... Or, skipping the commute altogether with remote work.
- wongarsu 7y ago
  > Building more capacity usually induces demand Viewed from a different perspective: we have so little capacity that most journeys are never taken. I agree that in general mass transit is much better than cars. But tunnels do remove many of the arguments against cars: pollution (both CO2 and tire abrasion) can be easily filtered, noise is blocked by solid rock, tunnels can be crossed without knowing they are there, they don't interfere with pedestrians, don't reduce building density, don't create artificial barriers. Cars are still incredibly dangerous, but Elon's sledges would solve even that. Cars still take up a lot or room both in transit and when parked, but most other disadvantages are reduced or eliminated by putting them in tunnels.
  - legulere 7y ago
    People will just start commuting to further away places like from barcelona to london: https://www.theguardian.com/cities/2015/aug/11/commuting-from-barcelona-a-london-worker-who-makes-it-pay https://www.theguardian.com/cities/2015/aug/11/commuting-fro... You can argue for an economical benefit, but it's very hard to argue that they are larger than the costs.
  - bluGill 7y ago
    Elon's tunnels don't solve anything. His cars are so large that the amount of people a tunnel can move is small. We can add more tunnels, but it isn't cheap, and geometry means we can't add enough - there is only so much space below us and you need to keep tunnels apart.
bArray 7y ago
> Imagine if we had cheap ways to build tunnels, no more > traffic, no more congestion, roads and parking lots would > only exist underground and cities would have more space > for gardens, parks, buildings, and walkways. Or, skip the tunnel building and just ban cars from major cities. Building more infrastructure to "reduce traffic" only makes using vehicles more attractive. The amount of congestion is approximately equal to the amount of congestion the average person using the infrastructure is willing to accept, so making it less congested just means more people use the infrastructure until the limit is reached again. The real answer to the problem is to simply ban all but buses and delivery vehicles - even then you can incentivize that they are electrically driven. Space increases and infrastructure maintenance costs are reduced, not increased. The real golden use for TBMs is for efficiency - i.e. Go around some mountain or go straight through it? Go around a city or go under it? I imagine buildings sharing a service elevator down to the tunnel where delivery vehicles can offload to and send goods up (rather than Musk's idea of trying to lift a several tonne vehicle in some personal elevator). Would likely make sense for all kinds of maintenance this way to, servicing water/gas pipes or electricity/internet lines for example could be as simple as removing a service panel from the side of a tunnel, rather than the terrible solution we have today involving digging up streets over and over.
- rklaehn 7y ago
  Why have technical innovation at all, let's just outlaw stuff... I really don't get this desire to outlaw cars. I like walkable cities, but I also like the comfort and privacy of car transport. I live in a place (Germany) with good public transport. I used to live in cities with very good public transport. I still don't enjoy being squeezed in with thousands of other people. Does that mean that people like me have to be reeducated and/or forced to see the error of their ways?
  - giomasce 7y ago
    I don't think that outlawing car is a solution, but disincentivizing them maybe is: higher taxes with which pay a better public transport network, less and more expensive parking, more lanes dedicated to public or unmotorized transport, traffic lights more favourable to public or unmotorized transport, stronger presumption of fault on the side of the motorized vehicle after accidents. All of these improve the value of less impacting transport. After all, cars, especially when moving just one person, heavily overuse shared and scarce resources like space and environment. It's all too fair that they pay a higher share to public resources. Maybe you will still use your car, accepting to pay a higher price for it, but other people will switch, making the world a better place also for you.
jtolmar 7y ago
You could replace highways with a magical teleporter and you'd still have traffic and congestion. Most traffic happens at the interface between the highway and the rest of the road network, as cars can only join the flow of traffic at whatever rate its capacity frees up - and cars entering the city compete for that capacity with cars leaving parking spots. Cities are already crammed full of street capacity, so the only way to increase capacity is to increase the number of people per car. And that solution, taken to its logical conclusion, is a train. Subways face similar problems to highway interchanges - passengers have to rejoin the flow of (foot) traffic. This is easier than with cars, since people are smaller and most of them can use stairs, but the cost of stations ends up being the larger portion of cost, not the cost of tunnels (which can be built more cheaply using cut & cover than they can with boring machines anyway). I'd like to see Musk throw his resources behind cheaper ways to make stations, instead of a problem that's better solved by digging a ditch.
TeMPOraL 7y ago
> While that's going on, please someone make a game out of building tunnels, it would be super cool! In a way, Minecraft is that game. At least when I played it couple years ago, I spent most of my time building metro tunnels.

baddox 7y ago

These animations are great, but for some puzzling reason they only advance while I am scrolling the page. To watch an animation I have to hold my thumb on the screen and subtly scroll up and down. This is on an iPhone X.

dingo_bat 7y ago
Works perfectly on Firefox, Android 10, Galaxy S10.

asdff 7y ago

Is there a reason why cut and cover isn't used very much these days, apart from mild disruption to car traffic?

jcims 7y ago
Utilities?
bskap 7y ago
Most of these tunnels are being built in heavily populated areas where surface space is at a premium. You'd have to tear down thousands of apartments and offices to make any meaningful progress on a cut and cover tunnel inside a city unless the tunnel is exactly following existing roads. That would be both very expensive and far more disruptive than just a little traffic
- afterburner 7y ago
  > unless the tunnel is exactly following existing roads I mean, a lot of subway projects are specifically planned to follow a main road simply because cut and cover is cheaper.
ant6n 7y ago
There seems to be a low tolerance to the construction disruption, especially to adjacent businesses and residents. Cut and cover also had high cost of moving infrastructure. I also wonder whether there's some relationship with the speed of construction - in NYC, ripping up the whole street to build a Subway was perhaps more acceptable if it's done in a year or so. One note: new cut and cover projects tend to actually use cover and cut: first the walls are built underground (often piledriven), then the top is covered with a concrete plate, then the Earth dug away from below. This minimizes the surface disruption.
KaiserPro 7y ago
it is ridiculously labour intensive. First, all utilities have to be mapped out, then any basements shored up. Then once the cut and cover is in progress, all utilities have to be re-routed, during, then replaced after the tunnel is cut. Then, the disruption of having major transit ways shut for n weeks. Lastly, there isnt a machine to do it. The TBM is pretty efficient labour wise.

spullara 7y ago

Or you could just move the surface streets a couple of stories up like they did in the early 20th century in Chicago. Trucks (for deliveries, etc) are not allowed on the surface, only below.

djsumdog 7y ago
A lot of early cities jacked up their buildings. Chattanooga did due to flooding. I somehow doubt such things could happen today considering the superstructure foundations under a lot of our modern buildings.
- spullara 7y ago
  Definitely easier to keep the buildings at their current level and just make a new entrance on the second (or higher) floor.
  - deleted 7y ago
    [deleted]
  - lmm 7y ago
    You can't bootstrap having a nice walking environment at above-ground level that way. Who's going to open the first cafe where there's no foot traffic? Why will anyone spend a lot of money on entrances that no-one's going to walk to? What pedestrian is going to want to keep walking up and down stairs while the network is partially complete. The City of London tried to do what you're suggesting and it was a total failure, because while it might have worked if it could have magically all been done in one go, there's no way to get to there from here.
- cududa 7y ago
  The only time cities have jacked themselves up is after fire or natural disaster. No way “underground deliveries” is scalable.

dlgeek 7y ago

Side note: Missed opportunity for the title "Interesting Boring Machines"

ant6n 7y ago
Actual title of article: "Far From Boring: Meet the Most Interesting Tunnel Boring Machines"

sytelus 7y ago

Here's interesting tidbit: Vast majority of underground railway network in Moscow was built in 1950s. Cost of building a mile of interstate highway in US is about $5M. Interestingly this cost hasn't changed since 1956 in inflation adjusted dollars when new 41,000 miles of interstate highway in US was laid out. It seems major cost is not tech but quite possibly regulation and/or government inefficiency/corruption.

wongarsu 7y ago
We have also use highways a lot more and accordingly require better construction. I'm not saying nothing interesting is going on, but construction+maintenance over 20 years, adjusted for vehicle miles traveled (or rather semi-truck-miles traveled) would be a much better indicator.

pugworthy 7y ago

I'm not out to analyze the clearly knowledgeable content of this article, but I'd not be surprised if someone wrote something just like it when he (Musk) started the whole illogical "make a rocket come back and land" stuff. It's not logical, but I'm giving him the benefit of the doubt. Let him do his thing. Who knows?

greglindahl 7y ago
One odd thing is the claim that it's just as cheap to bore a much larger tunnel. Yet no one is bidding a much larger tunnel boring price anywhere close for either the short Las Vegas tunnel or the much longer Chicago one.
- newyankee 7y ago
  It is not odd i think it is a thinly disguised lie. If it was serious it would've done a point by point rebuttal of Elon's proposals and why he think he can reduce the cost more than 10x for same capacity (capacity is the operative word). At the very least it could've shown cost calculations for these tunnels. If they are as attractive as portrayed we would've had many more of them.
  - Gibbon1 7y ago
    Calculate the diameter of two small tunnels that can carry a lane of traffic vs one that can carry two lanes. Single lane, 12 feet wide, 12 feet tall. Requires a tube 17 feet in diameter. Or 54.3 feet circumference. Two of those is then 108.6 feet. A tube that can carry two lanes, 12X2 = 24 feet. Diameter is 26.8 feet or 84.3 ft circumference.
    - superice 7y ago
      Except that in tunnel boring the circumference is not that relevant, it's the surface area of the cross section of your tunnel. In the first instance that's 113.1 square feet, in the second it's 452.4. Every time the radius doubles, the surface area quadruples. The perfect tunnel transports people horizontally in a very narrow tube.

tiku 7y ago

Why can't we just vaporise stone with lasers..

Animats 7y ago
It's been proposed. By Disney. 1958. [1] https://youtu.be/TwA7c_rNbJE?t=137 https://youtu.be/TwA7c_rNbJE?t=137
- dr_dshiv 7y ago
  My favourite video of all time.
- dredmorbius 7y ago
  The success rate of those predictions is ... low. At 60+ years, only a couple are commonplace or in effect, mostly the inducement of sprawl. Virtually all the rest assume vast amounts of free power which never materialised. The automation examples are only now, and with great difficulty and challenges, appearing. Litho-annealing / vitrification remains a fantasy. Lasers serve as alignment aids, not boring mecganisms. Any idea who commissioned/ contributed to this?
wongarsu 7y ago
The boiling point of limestone is around 825°C or 1515°F. Heating up a tube of multiple meters diameter and multiple kilometer length to that temperature would require insane amounts of energy. A laser makes it possible to efficiently heat a small spot to that temperature which helps reduce waste heat, but you still have to heat every spot at some point.
- polemic 7y ago
  I wonder what you do with a jet of vapourized rock too, once you've got it to that temperature!
  - lstodd 7y ago
    Well I guess one can suck the plasma into a condenser unit and then on to a conveyor belt for extraction. Now what you do when those lasers hit a high-water-content sediment and cause a vapor explosion, loss of integrity of surrounding rock and flooding?

Animats 7y ago

Musk could help with the back end of the problem. The TBM up front gets all the attention. Behind the TBM is usually a temporary two-track narrow gauge railway line, with muck cars carrying dirt and rock out, segment cars carrying tunnel wall segments forward, plus tool cars and worker cars now and then.[1] Hanging off the back of the TBM is all the machinery to move all those heavy items around.[2] Including the machinery for laying more railroad track behind the TBM. Self-driving electric muck cars, segment cars, etc, might replace that temporary rail infrastructure. That's something Musk's company could address. The back end of the process seems to get less attention than the front end. Most of the length of the TBM is devoted to material handling, though, as is the rest of the tunnel all the way back to the entry. A big fraction of the cost is in moving all that stuff around. [1] http://www.zslocomotive.com/products http://www.zslocomotive.com/products [2] https://youtu.be/SY3Q9GqUYro?t=115 https://youtu.be/SY3Q9GqUYro?t=115

newnewpdro 7y ago

The vertical shaft sinking machine process is basically just an automated form of the old-school manual method of digging a well with men and shovels. Laborers excavate at the bottom while new bricks are laid incrementally forming the casing at the top. The whole column of bricks slides down as a cylinder whenever progress is made at the bottom. I've long wanted to dig a well that way, it's gotta be surreal to be at the bottom digging away with a little shovel and seeing a towering column of bricks move as one to fill in the progress. It can't be terribly safe :)

jaclaz 7y ago
>The vertical shaft sinking machine process is basically just an automated form of the old-school manual method of digging a well with men and shovels. Yes, and the whole staff seems a lot more theorical than the rest, the approach can only work in a subset of terrains and for relatively short shafts (if you exceed certain lengths or in many terrains the attrition between the shaft walls and terrain will stop the sinking). Usually in tunneling projects ventilation shafts are dug "traditionally" (if rather short) or by "raise boring" (if longish). Some related videos: https://www.youtube.com/watch?v=V2oWTk4khvg https://www.youtube.com/watch?v=V2oWTk4khvg https://www.youtube.com/watch?v=6QueB4GCQww https://www.youtube.com/watch?v=6QueB4GCQww
KaiserPro 7y ago
the "vanilla" TBM is an automated version of this: https://en.wikipedia.org/wiki/Tunnelling_shield#/media/File:Thames_tunnel_shield.png https://en.wikipedia.org/wiki/Tunnelling_shield#/media/File:... just with prepoured concrete blocks instead of bricks.
lstodd 7y ago
Here's an absolutely insane guy's channel https://www.youtube.com/channel/UCti7FZiCHC5fhvgN_Ns_5ew https://www.youtube.com/channel/UCti7FZiCHC5fhvgN_Ns_5ew He digs wells by hand. Very scary videos.
- goatsi 7y ago
  There we go: https://youtu.be/5-j-EHXhBh8?t=465 https://youtu.be/5-j-EHXhBh8?t=465

lazysheepherd 7y ago

Article does not seem to understand what Booring Company trying to achieve. It does not even seem try to understand. We all know it's very popular to love Elon Musk. But it's generally more attractive to one-up those who do and hate Elon and his "fans". As a disclaimer: I am in the wagon of "please leave this guy alone so he can do his thing, whatever it might turn out to be". And I do not see any value in this article. Booring Co. is about creating rich network of very small tunnels _to solve urban traffic,_ whereas article only talks about creating huge tunnels for longer distance transportation. Article seem to be making a comparison while things it compares aren't in the same category nor does they try to solve the same problem to begin with. Incoherent and poorly thought-out", if not straight clickbait.

projektfu 7y ago
The article only briefly mentions the Boring company and Elon Musk, because it's mainly about how cool these large tunnel are and how the machines are large enough to allow multimodal transportation in a tunnel. The comparison to Musk is that his company is making a bet the rest of the industry has rejected. They are all building large, versatile tunnels. Musk is betting that small tunnels will be the future. Who knows? What I got out of the article was definitely not an "anti-Musk" vibe. Not even super critical of the Boring company approach. It was more of a "modern marvels" type of article.

k_sze 7y ago

Is Elon Musk a Samuel Beckett fan? I can totally picture a city council asking what's taking a tunnel project so long to complete, and Musk answering, with a straight face, "Oh, we're just waiting for Godot."

rmason 7y ago

I'm not sure that I agree with the author on Elon Musk's tunneling ambitions. Far more people are betting against him on Tesla and SpaceX without much success. One thing lost in the debate is if the costs are lowered it will also increase the number of cities where a subway is possible financially. I see cities spending huge money on dedicated bus lanes. The bus companies adore it but I'm pretty certain that the return on investment is abysmal. They tried to implement it locally and the grass roots groups put up such a huge fight the politicians withdrew support for it. As far as the cost of the stations I wonder if anyone has given thought to using 3D concrete printing? Admittedly it would be easier if you excavated from the surface as opposed to widening a tunnel but I still think it has the possibility of losing costs. https://all3dp.com/2/concrete-3d-printing-how-to-do-it-and-applic https://all3dp.com/2/concrete-3d-printing-how-to-do-it-and-a...

walkingolof 7y ago
"Musk says he can build tunnels cheaper if he just makes them smaller. But in reality, it’s not small TBMs that are the future, but big ones. The cost of a TBM doesn’t get much higher as you increase its diameter. Tt is therefore cheaper to build one very large tunnel, rather than two smaller ones." If that is true, then Elon is betting on the wrong horse.
- rmason 7y ago
  I can remember articles promoting hydrogen powered cars as the future. They even said Elon made the wrong bet with electric. Some company's are still hawking hydrogen as the future, the difference is no one is paying any attention to them any longer. Someone else has made the bet for bigger tunnels and they're using a PR agency to push back. PG called out this tactic a few years back: http://www.paulgraham.com/submarine.html http://www.paulgraham.com/submarine.html
  - bluGill 7y ago
    The bigger tunnel people have proven success, while the small tunnel people just have hype. People shut up about electric cars over hydrogen when electric proved itself. Note that back when this started there were many hydrogen naysayers who pointed out all the problems the hydrogen proponents have faced. The electric car people got lucky that lithium batteries advanced to where they could work - 20 years ago this wasn't a given to battery experts.

topmonk 7y ago

I know this is probably a very stupid idea, but I was thinking what if we shot ourselves out of rail guns into the air into a bullet shaped craft with fins? You could be shot out of one rail gun in San Francisco, glide for awhile, fall to the earth and caught by a “reverse” railgun in San Jose. It'd be cheaper and safer than planes since no need to carry fuel or an engine on board, and could have an emergency parachute incase something went wrong. Or maybe I've been dreaming about Kerbal Space Program projects too much lately. (I'm fully expecting to be flamed and jided for this)

rkangel 7y ago
It's a fun idea, but G-Force makes it unusable for people. The speed to which you'd have to get, over the length of the barrel would make it unsurvivable, or at least very unpleasant.
arethuza 7y ago
This sounds like a failure mode for Hyperloop. Edit: Also reminds me of a rather entertaining failure mode for UK AGR nuclear plants - but that's another story.
tim333 7y ago
Not so sure about the "safer than planes" - planes are pretty safe really. Also I think the initial acceleration would be uncomfortable for passengers if they somehow retained consciousness. Edit - the US navy rail gun apparently produces 60,000 G, humans black out around 10. You might just about be able to do SF to San Jose with a glider and winch launch if they improved the tech 3x or so. Longer cable etc.
- Retric 7y ago
  Time is a major component of g force tolerance. Healthily people can take 15g’s for short periods without issue, but extend that to a minute and it can prove deadly. In ideal conditions linear acceleration to Mach 2 at 5, 10, even 20g is fine. But, if you want to go much faster the limits are reduced significantly. The Soyuz for example can hit 8.5g’s for about 60 seconds in some situations which adds up to ~Mach 14.6 and is a rather extreme situation.

morekozhambu 7y ago

> Rather than including a facility for assembling the tunnel lining (out of multiple segments) inside the TBM, complete rings are inserted at the insertion shaft, and the whole tunnel is jacked forward one segment at a time. This seems inefficient.

bluGill 7y ago
Looks to me like they are looking at only going a short distance. I doubt you could get more than 100 meters like that, but if you only need 100 meters of tunnel it is probably cheaper because it is faster.

choeger 7y ago

I think one of the major causes for the high cost of tunneling is that it is done too seldom. Any major city in the world probably has room for 10 or so additional tunnels, so why do they not operate a fleet of TBMs constantly for the next n years?

ksec 7y ago

I have many questions, 1. Are any of these TBM considered state of art? I dont see any tech inside those TBM that could not be done 10 years ago other than the cost of the machine. We are entering new Space Race era and yet some fundamental stuff still looks very, should I say "traditional". 2. Why cant we build even bigger TBM? Like Double the current diameter. Or Bigger TBM that are Rectangular rather than Circle. 3. The biggest problem with TBM is that they are slow. Even if we had made them 10 times faster I would still consider them very slow. Surely there could be technology that improve on it? 4. Are there any reason why we dont use TBM for small pipes, ( like for electricity or fibre optics, )

sjwright 7y ago
TBMs can only go as quickly as you can shift earth out of the tunnel. Increasing the diameter hugely increases the volume of earth. If you want to excavate a rectangular tunnel, you want a roadheader. https://en.wikipedia.org/wiki/Roadheader https://en.wikipedia.org/wiki/Roadheader
- bobbydroptables 7y ago
  Increasing the diameter proportionally increases the exit pathway through which you can shift earth out of the tunnel. Obviously there are complexities in the field that I'm not aware of but these seem like problems you can engineer around. It's really surprising to me that in 2019 the limiting factor in a billion/trillion dollars industry like transit is something that could be solved with a better conveyer belt. To ask OP's question another way: many areas of technology and engineering have improved rapidly over the last decade or three. Have TBMs been keeping up?
  - sjwright 7y ago
    Increasing the width of the exit pathway doesn't increase the rate at which you can deal with the mountain of crap piling up at the end of the tunnel. You sound like Elon Musk. "This problem seems easy. Clearly all existing TBMs suck so we'll just build a better TBM!"
7y ago

LargoLasskhyfv 7y ago

I'm uninpressed because it lacks Nuclear Tunnel Boring Machines like in [1] and [2] as envisioned by [3] for [4] and [5] in 1972 and 1978. Which all Hyperloop afficionados should read, if they haven't done so already :-) [1] https://patents.google.com/patent/US3693731 https://patents.google.com/patent/US3693731 (I'm wondering about steam explosions when hitting ground water, which is not unheard of. But...NUKULAR!) [2] https://en.wikipedia.org/wiki/Subterrene https://en.wikipedia.org/wiki/Subterrene [3] https://en.wikipedia.org/wiki/Robert_M._Salter https://en.wikipedia.org/wiki/Robert_M._Salter [4] https://www.rand.org/pubs/papers/P4874.html https://www.rand.org/pubs/papers/P4874.html [5] https://www.rand.org/pubs/papers/P6092.html https://www.rand.org/pubs/papers/P6092.html (Lacking cheaply mass produced super-conductors here)

vpribish 7y ago

"The cost of a TBM doesn’t get much higher as you increase its diameter." This is the key assertion, and it is unsupported. - heat extraction will become a bigger problem - debris extraction too - cost of parts, cost and speed of logistics like transport and installation of the machine will be worse - small number of exotic large TBMs will scale worse than large number of small TBMs in manufacturing cost and operating experience - I've seen elsewhere (citation missing) that small borers move much faster than large so any costs that scale with time will be worse. - risk-wise: a portfolio of small borers will have less risk than an all-eggs-in-one-basket gamble. a broken part delaying a big machine incurs more cost than ona smaller machine. unless your project requires a single enormous bore I think you would prefer to use the smallest you can get away with. The author does not seem to have any relevant experience, so I'm not going to take this on his authority; he's a programmer who has done scheduling software on metro projects and is working on an MBA. Interesting summary of types of machines though!

astrodust 7y ago
Key word "much".

teslaberry 7y ago

boring tunnels is dumb. ground shifts, and more importantly , there is hydrology as a problem. the right approach is the opposite to 'boring'. driving pylons into earth to make it even more rock hard if it isn't already bedrock. then you build UP AND IN 3 DIMENSIONS. the problem is not that we cannot dig. the problem is that we have no mastered 3dimensional building. what many people don't get is that a very large part of our technical deficiencies in this regard , result from a lack of investement in specific construction technologies becuase of a root problem in THE LAW. the legal system has dramatically languished in the face of new potential technicailities. instead, it has continued to support a 2 dimensional 'foot print' system, and an anachronistic 'air rights' system of strict property law has then been layered on top of it to enable rights to build 'up' to a point. right now , it's easy and cheap to build up to 100 meters. relatively . building higher is stupid and unnecessary, building lower is lazy and even dumber. the cities of the future(s) don't ahve better cheaper tunnels under them, but bettter cheaper 'tunnels' going through out them. above ground. rather these tunnels would be considered 'rights of way' and the legal frameworks around them would be complex, but enabling, rather than what we have now, a legacy system impeding progress. other than water and steam mains and natural gas mains, which carry extremely heavy water, there is almost NOTHING you cannot put under above ground inside a building. nothing. there is NO reason to have a 'subway' made out of giant metal things weighing insane amounts of weight. just build this thing together. nothing is going to stop us....now or later.