Guest Post by Willis Eschenbach
A recent article has discussed how Elon Musk’s “Boring Company” has raised $113 million dollars in startup capital. This is the company Musk formed to drill the tunnels for his proposed “Hyperloop” transportation system. It has encouraged me to discuss some of the engineering and practical problems with his LA-to-San Francisco Hyperloop proposal. The Hyperloop concept involves a windowless “pod” traveling at just below the speed of sound in a tube with all the air evacuated from it. There’s a reasonable description of the Hyperloop at Wikipedia and a much more hyper description at their website. It all sounds so good and so 21st Century, what’s not to like?
In no particular order, the problems with the Hyperloop include:
Vacuum: The Hyperloop requires a near-perfect vacuum to run at the proposed speeds. It has been tested with a one-kilometer long test track. The test track was billed as the “second largest vacuum chamber in the world”, after the vacuum chamber of the Large Hadron Collider.
But the LA-to-SF route is 615 km. This is a huge, almost unimaginable step up in size and problems. Consider that although the LHC is carefully internally braced to keep the pressure from collapsing it, they’ve said the Hyperloop tube will be a 1″ thick steel pipe supported on pillars. There’s no way to brace it internally, the pod has to run through the middle. The day/night expansion on that much steel would be very large, and the expansion joints for that use have never been built. In addition, atmospheric pressure on the tube would be about ten tonnes per square metre … and there’s a 15-tonne “pod” running through it, putting large stresses on all bends and joints.
This means that if the vacuum is breached for any reason, say a car runs into one of the pillars, or some fool shoots an high-powered rifle round at an expansion joint, or terrorists place even a small bomb anywhere along the length of the route, or a small thermally driven “kink” in the pipe develops, or heck, a ubiquitous California earthquake, everyone in the tube would die from the instantaneous deceleration. Here’s what happens to a railroad tank car with ~ 1/2 inch (12 mm) steel walls when it is not properly vented … it collapses from nothing more than the atmospheric pressure, and that is without a near-perfect vacuum inside.
Ooogh … you don’t want to be inside if that happens.
Thermal Expansion II: A difference of only 3°C from the top to the bottom of the tube will cause differential expansion of about 25 metres from top to bottom of the pipe over the length of the SF-to-LA run … very no bueno. The pipe will tend to either lift out of its supports or bend at the expansion joints … joints with a 15-tonne pod going through them at 750 mph.
Energy: The pumps necessary to keep the tube evacuated will be quite large. Remember that each pod has to be air-locked in and out at every station. The energy cost of this constant pumping at each station is unknown, but definitely not small.
Pod Integrity: The pod will be in near total vacuum. Airplanes fly at about 33,000 feet (10,000 m). The pods will be traveling at the equivalent of 50,000 feet (15,000 m). This means that if there is the slightest leak, there will be catastrophic decompression and everyone in the pod will likely die.
Passenger Throughput: This is likely the biggest problem with the Hyperloop—for all of its speed, it is remarkably slow at actually moving people. Consider the competing technologies. Freeways typically carry 2,000 cars per hour per lane, that’s maybe 3,000 people per lane per hour. So a four-lane freeway of the type common in California will carry about 12,000 people per hour.
A subway with three-minute headways between cars will carry about 36,000 passengers per hour. The proposed and insanely expensive high-speed “Bullet Train To Nowhere”, which Governor Moonbeam is trying to build fro LA to San Francisco will carry on the order of 12,000 people per hour.
Now, Musk claims that a pod will depart SF-to-LA and LA-to-SF every 30 seconds carrying 28 people per pod. That’s the best case, and it’s only 3,300 passengers per hour.
But wait, as they say on TV, there’s more. In general, you don’t want to run cars, trains, subway cars, or Hyperloop pods so close together that they can’t stop safely in case of an emergency to the car ahead. Humans can only sustain about half the force of gravity, called “0.5 G”, for safe deceleration. Musk says the cars will be traveling about 760 mph (1225 km per hour). At that speed, it will take around 75 seconds at 0.5 G to decelerate to a stop. So the inter-pod time has to be at least 80 seconds … and that means passenger throughput drops to 1,260 passengers per hour.
And the bad news doesn’t end there. The whole system can only run as fast as the slowest segment of the Hyperloop, and that’s the stations. Remember, at every station, the pods need to be depressurized. Then passengers need to get on and get off, and the pods need to be repressurized. Musk says that up to three pods will be in the stations at once. So that means that depressurization, passenger unloading and reloading, and re-pressurization need to take place in about two and a half to three minutes … and you better hope that nobody forgets anything on a pod and has to go back to get it, or the entire system slows down.
Net result? The Hyperloop will make less than half the difference in passengers transported, and likely much less than half the difference, that would be made by adding a single lane to the LA to SF freeway …
In Short: The Hyperloop is extremely dangerous to passengers, vulnerable to a host of problems, will kill everyone inside if even a small failure happens, moves a very small number of people, and oh, I forgot to mention … what happens if the power fails, as happens these days in California all the time because of our insane renewable mandates pushed by our less-than-genius Governor, Jerry Brown. Care to think about being stuck inside a windowless pod inside a steel pipe on a hot day in the California desert, with no way to escape?
And all of that for less gain than adding a single lane to the freeway … but there is one thing we can be sure of.
Elon Musk will get even richer from government subsidies for his latest whiz-bang proposal … truly, the man is a subsidy artist. Where most of us can see nothing but government boondoggle and waste, he sees personal wealth.
My best to all,
w.
THE USUAL: When you comment please quote the exact words you are discussing, so that we can all understand your subject. In addition, rather than telling me or anyone that we are doing something wrong, please demonstrate the right way to do it.
Men are not getting better… Lol
Oops, link to the original discussion here:
http://www.transterrestrial.com/?p=67555
Smaller engineering issues can be handled- thermal expansion is controlled by expansion joints, and seismic events can be detected before the s-waves arrive and command an emergency stop. Emergency stops can be done at two gees- that’s what seat belts are for- and the hydrogen-filled tube is entered and exited with a section of nitrogen-filled tube to prevent mixing with air. When not moving at maximum speed, the cars can simply run in air, and fan out to multiple stations at either end (in the extreme, driving autonomously they take you door-to-door). The loading and unloading of individual cars is thus decoupled from the high speed tube scheduling.
“Emergency stops can be done at two gees”
So you’re going to require passengers to take a medical before they get on board?
Only one quibble… the pods would be at atmospheric pressure at the stations so when sealed they would not need to be pressurized. However, the station would need to be resealed and depressurized before the airlocks could be opened, so no difference in terms of time required.
Musk has shown the ability to find some amazing engineers – eg. landing Space-X rockets – and great engineers can solve some really hard problems. But great engineers should also recognize that even if they can deal with technical issues, issues of economics and safety sometimes make an idea impractical. The Hyperloop idea seems to me to be one that could not be justified on economic grounds alone. It would most likely never be built unless massive subsidies are involved.
While, I do still see all sorts of other problems, In regards to the need to vacuum out a chamber, to insert the pod into the tube, I can see one solution. How about if there is an intermediate pod older, that can rotate out from the vacuum chamber, like a revolver gun. This intermediate pod, could be designed to hold the passenger pod, with any extra space filled with solid material.
This arrangement can, theoretically allow for passenger pod insertion/removal without pumping at all.
Some of the other technical issues may also be solvable. But, of course, the question if if it worth the cost.
Let him work it out. A similar critique of his proposal to land and reuse booster rockets on floating barges could have easily been made. Right until they did it. Also, this whole analysis presupposes that the entire loop needs to be a vacuum. That’s not true. Only the air in front of the pod needs removal and then it becomes a rate equation of how fast air can be moved and what does the work to remove it. That simplifies the initial conditions, stresses and margins.
That’s a specious strawman.
Nor is criticism about recovering boosters anything similar to the litany of safety, production and operating concerns that have been raised in Willis’s article and this thread.
Especially since both Russia and America regularly recovered and reused boosters used for space launches.
Criticism regarding recovering and reusing rocket components ignored common practice for space launches.
Let Musk build the tube. Without any use of tax payer funds!
Given Musk’s pretentiousness, Musk should build and operate the beastly thing using only renewable energy, including manufacturing the steel pipe.
“Also, this whole analysis presupposes that the entire loop needs to be a vacuum”
NO
It’s what the proposal says. (Proposals actually. There are many possible variants.)
We can only discussed what Elon Musk is suggesting. If YOU want to propose another design, than go for it. (Any change to fix one issue introduces many other issues.)
The density of 0.084 kg/m3 for H2 at STP is equivalent to air at 20.2 km, or roughly 66,000 feet, so the drag on a car in the tube would be far less than for an airliner at 35,000 feet or so.
So bottom line, I agree that a vacuum tunnel is a bad idea, but a hydrogen tube could be a good idea and may be useful if someone less busy than I am can do a serious first-order design.
The entertaining part is that fossil fuels are the only economical method for extracting hydrogen.
“tube would be far less than for an airliner at 35,000 feet”
But nobody proposed “an airliner at 35,000 feet”, AFAIK.
The proposals mention 100 Pa. That’s almost empty space.
How could ANYONE spend even a dollar on this nutty idea?
California. Nuff said.
Anybody that thinks they need to move that fast:
1) Should move closer to the hive.
2) Consider Skype, or those new video chat platforms I’m way behind on.
3) Maybe you take one trip thru the tube, just to say you felt what a 10 g acceleration felt like, and it didn’t even spill your coffee.
Within 15 years, autonomous vehicles
≠============
Not sure about the date, but it is most certainly a game changer for public transit in all forms that will eliminate entire industries.
What it does mean is that roads will remain the primary means of moving people. Mass transit systems on fixed rails will make no sense when private vehicles can go out and make money for their owners. Instead of paying for parking while at work your car will be out making money to pay for fuel, insurance, maintenance, etc. End of the day after making a few hundred $ in fares it drives up to the office to pick you up and take you home.
As an engineer I find myself intrigued by the possibilities of the hyperloop and its various technological difficulties.
I do believe it is prohibitively expensive and the cost of construction and running the system would make the price of using the system…astronomical.
This is an example of identifying a problem and creating a solution without acknowledging the constraints that the solution must meet.
On a side note, it is quite humorous to read all the negative commentary about the Hyperloop. I am certainly not a fan, but if you were to replace the word hyperloop with airplane with all these negative comments you would assuredly be entertained.
Self-flying aircraft will make this scheme and high-speed trains unnecessary.
Every industrial and commercial park, or large campus like Apple’s, will have its own landing strip. The planes might even be tilt-wing, so as to land and take off like helicopters, obviating the need for strips.
Yeah,as soon as we change physics. I mean flying is sooo energy efficient. /sarcasm
Look up the MPG for a small plane or helicopter
My thoughts exactly. “Imagine a tube moving near the speed of sound. to achieve this, we’re going to elevate the tube to 35,000 ft to reduce drag. We will pressurize the tube to keep passengers comfortable.” Oh wait, you mean it actually works, is used everyday by millions and changed the world?
It works well within constraints.
1. Cost benefit for passengers, they’re the ones paying for the service.
2. Destination, the destination has to be useful to the passengers.
3. Speed Vs safety, there are other forms of transport out there, at competitive prices.
Planes work well, but the Concord was dumped simply because it’s particular need (cost-benefit) wasn’t viable.
An earlier go “Atmospheric Railway”
http://www.ikbrunel.org.uk/atmospheric-railway
At least you could look out the window
Pure subversion.
All the charm and risks of traveling in a submarine submerged at a depth of x-hundred feet, only a lot faster, and what’s left of you when a failure occurs can be scooped up on dry land.
Don’t forget the nifty, the-power-is-free solar panels on top of the tube sections (see 1st drawing). Surely they will have a major effect of reducing operating costs (but are really there to get government subsidies).
So after an earthquake BART inspects tracks, an example here took around two or three hours, using trains: https://patch.com/california/piedmont/bart-inspects-tracks-following-earthquake
BART has 112 miles of track, though not sure if that’s distance of the routes or the actual tracks (e.g. a route typically has two sets of tracks for each direction). It also has a maximum speed of 80mph.
I wonder how much checking hyperloop would need after an earthquake & how it would be done, sensors only or running inspection cars at a lower speed through the tubes?
Elon Musk’s answer to everything: “track” (tube) inspection will be done by robots.
The crushed rail car is a poor example.
A tube with external steel braces (circumferential and/or longitudinal) or simply selecting a longitudinally crimped tube would be sufficient to bear the vacuum induced compressive stresses. Other engineer issues can also be solved as long as someone sprinkles money all around, a la Moon Project.
Certainly, no private investor will put money for this project which will never be a cash flow positive. Hence Musk wants government (the taxpayer) to subsidize this project.
Why should this be our government’s priority?
“Other engineer issues can also be solved as long as someone sprinkles money all around”
Probably not. You need to make the system mass transport system-safe. Not just mission to the Moon-safe.
But the project was presented with a budget. The sketchy project presented was based on existing, proven technologies. This is obviously a crook.
Before I knew anything about the technicalproblesms, I was aghast at the idea of being stuck inone of those pods, unable to escape. And the likelihood of a terrorist planting an explosive on the tube.
The elite need speed and chic and tax credits. Let the others eat carbon tax cake.
A more in-depth look at the concept was published here about 5 years ago, and it addresses each of the challenges listed above. The least of these, IMHO would be tube buckling due to atmospheric pressure. The tube radius is 65 inches, and the pressure load 14.7 psi. That’s a buckling stress of only 956 psi. Preventing buckling is simply a matter of adding external stiffening rings ever 10 feet. It’s the other loads that would dominate.
As for a cabin depressurization, this is not a much different problem from the Concorde, which cruised at 60,000 feet. Oxygen masks would be useless at that altitude, so the designers made the windows much smaller than on other jets. The pilots would go into a maximum angle dive at the first sign of cabin depressurization. If caused by a window blowout, the area was small enough to keep pressure in the livable range until the air packs could keep up with the bleed. Loss of a door, however, would have been un-survivable. The hyperloop cabin has no windows, which eliminates a lot of the problem. Elon has had a great deal of experience, no, flying a habitable cabin in space, and even with big windows and doors, Dragon has never had a problem.
The acceleration limit of 0.5 g is puzzling. Here is a list of the 9 fastest launch acceleration roller coasters in the world. Ninth is the Takabisha, at a modest 1.4 g. I’ve been on both the Xceleerator and Storm Runner (both a blast at 1.6 g). Number 1 is Japan’s Do-Dodonpa, which goes from 0 to 111.9 mph in a blazing 1.8 seconds (3.27 g). Stopping is just the inverse of starting, and I’m sure that 12.2 seconds at 3.27 g would be more acceptable to passengers than an instant stop from 760 mph.
Anyway, it’s an interesting read from the perspective of an engineer. Enjoy.
(PS: That tank car collapse was gnarly!)
Thanks for the thoughts on how to improve the concept, Michael, much appreciated. I was writing about the concept as it has been pushed by Musk. Yes, there are possible changes that could make it work better. My point was that what is being sold at the present time is not feasible.
I would add a couple of points. First, you say “Dragon has never had a problem” … in how many hours of operation in space? A few days worth? A week? We’re talking about something we expect to run 24/7/365 …
Second, the Dragon in a vacuum is not doing 750 MPH in an evacuated tube … it’s basically drifting in space. Nor does it possibly have suicide-minded bombers on board, or idiots with rifles taking pot-shots at it …
Finally, yes, I’m sure a young strong man like Colonel John Stapp can withstand over 40 G deceleration, and it sounds like you’re happy at 1.5 Gs … but we’re talking about infants that may not be strapped in, and old people with cardiac problems, and 300-pound folks with breathing issues, not you or Colonel Stapp. I wouldn’t advise strapping any of those classes of folks into the Do-Dongpa … but they will definitely want to ride a Hyperloop.
w.
There have been 13 Dragon commercial cargo resupply missions to the International Space Station (CRS-7 was a launch failure, CRS-14 is currently berthed at ISS), and they last an average of 30 days. Dragon goes through environments during powered flight, atmospheric entry, and landing that dwarf anything seen by a land vehicle. And CRS-14’s Dragon is on its second trip into space, the first having been CRS-8. It’s the second CRS mission to use a previously flown Dragon. All told, Dragons have chalked up around 377 days in orbit. It’s a testament to SpaceX that NASA allows Dragon to be part of the pressurized volume of the ISS for weeks at a time, and is going to fly astronauts into space in it beginning next year.
One other thing about the environments. Space isn’t all that benign. On top of such things as huge, rapid temperature swings and large temperature gradients, there is the growing problem of micrometeoroid and orbital debris (MMOD) strikes. At velocities that can be in the tens of thousands of feet per second, even a paint fleck can do a lot of damage. Before the first test flight of the Orion capsule, the NASA MMOD analysts were putting the odds of a mission failure at between 0.01 and 0.001. The problem was that the Delta IV upper stage (required for the entry burn) has high pressure helium tanks on the aft end, and they aren’t shielded. The vehicle was only up for 4 1/2 hours. To have such a high probability of failure in so short a time illustrates how severe the environment is. Dragon is a pretty big target, but is designed to handle strikes up to a certain size.
Sorry to go on like that – I do this for a living, and like it. I have to keep reminding myself that most people don’t find it as cool as I do.
I was thinking the same thing as well…..also having ridden many rollercoasters, including some of the launched ones like Storm Runner. There are also some that have some pretty hard stops as well (depending upon how the trains are blocked and how many can run the circuit at a time). But then again, those kinds of rollercoasters also have sophisticated restraint systems designed to keep passengers from being thrashed about too much. On public transit no one is going to want to strap in like a fighter pilot…..Probably the most that passengers would be willing to do would be to put on a seatbelt like in an airplane. That, and as the author of this article has mentioned, some people will be unwilling (or unable) to be subjected to such forces.
Also rollercoasters have a set of criteria on who can envoy the ride (“you must be that tall”).
A mass transit system cannot afford these restrictions. No public body is going to subsidize a transport system that severely restrict who can travel, especially is “protected groups” cannot use it. It’s just a non starter, from the point alone.
Whatever one thinks about the economic prospects of Musk’s other companies, his cars do at least work, his spaceships do reach orbit, and solar city can generate some electricity on a sunny day. This hyper-loopy thing can only detract from general confidence in them, and from confidence in the person at the helm. Man will walk on Mars before this works. It would be frightening if it wasn’t so funny.
Take that back. It is frightening, despite it being so hilarious.
All of his successes require one thing, subsidies from the government. The one true thing he is really good at is making himself rich with other people’s money.
If we assume 1” wall thickness, 11 ft diameter, how many miles could be layed given current world steel production?
The quantity of resources needed for this is staggering.
A 500 km tube, unreinforced, would weigh 1 million tonnes. The US produced 85 million tonnes of steel in 2014, and has produced as much as 140 million tonnes in a single year (1970). I really don’t think resources would be a problem. Currently we’re utilizing 75% of our capacity, and the remaining 25% is more than enough to build the hyperloop in just one year.
And this Willis,
“And all of that for less gain than adding a single lane to the freeway … but there is one thing we can be sure of.”
is the hammer on the nail.
Thank You for encapsulating the insanity of this state in one sentence.
I do travel up and down I-5 and !-99 a few times a year, an extra lane or two would be nice.
But
I live at the junction of I-395 and I-14 at the north end of the Mojave desert. I-395 is a notorious highway of death. 2 lanes for 65 miles, and it is a major highway used by Socal to head to Mammoth etc. And a major truck road. Just last week another local couple were killed in a headon on 395. I-14 isn’t as bad but it STILL has 2 lane sections.
This idiot governor can’t be bothered about bringing the state highways into the modern age but pulls all the stops out for his stupid train.
I’d respectfully submit that collapse of the tube isn’t as big of a deal as you make it out to be WE. The pressure loads are trivial compared to what subs endure. The tank car video, while entertaining, isn’t relevant since those cars are not designed for such a load.
External ring and stringer stiffeners would suffice – think of it as a standard airplane fuselage turned inside out, approximately. A simple shell “only” as the tank car video shows is wouldn’t be an ideal solution. Alternatively, an external pressure shell with internally placed ring frames and stringers as the structure, with an inner liner to define the tube way for the car might be another engineering solution. Note that I suspect submarines are built this way (certainly the WW2 vintage ones, not sure on the current types) – there is a pressure hull distinct from the external, hydrodynamic shell in WW2 boats, and there certainly could have been an inner liner hull distinct from the pressure hull just as easily.
I also don’t see the joints needed to handle thermal expansion / contraction or external imposed loads as being too big a deal. Note that simple fabric coated rubber core “P” and “Y” seals pressed into the adjoining fuselage structure are used to seal the doors of passenger airplanes to 8 PSI. Put 4 such seals (2 primary, each taking ~1/2 the load, 2 more as fail safe) in series at a “tube inside a tube” slip type joints and there you go – pressure sealed with flexibility as well. If you do this in the context of a tube-in-a-tube arrangement, the car will never encounter one of the pressure loaded slip joints, being isolated to the inner “liner” tube. Supports that impose proper section-to-section alignment across the tube section joint while allowing linear flexibility of the tube sections are trivial in concept (tube mounted rails, with interfacing support mounted rollers that constrain relative lateral displacement without constraining linear displacement).
Where I see the issue with this whole concept is simply the economics. Can the cap & running cost generate sufficient risk adjusted income to make it worth while? At this point, I’d be highly skeptical on that part.
No Name Guy April 18, 2018 at 3:42 pm
Thanks, Guy. I was analyzing the proposal as it has been put forth by Musk. Could it be improved? Sure. What can’t be improved? But that’s not the question.
The question is, can it be done safely and economically in such a way that it makes more sense than adding a single lane to the existing freeway?
To that, I’d say no.
w.
Doesn’t that depend on the goals?
Adding an extra freeway lane doesn’t get journey times to “35 minutes” which I would of thought is the main benefit of hyperloop.
Of course what the actual improvements in door to door time would be is another matter, the general claim that LASF time is almost a wash between driving and flying (given check-in etc.), even with hyperloop would there still be a four hour door to door time for a real journey?
climatebeagle April 18, 2018 at 5:10 pm
Per the current plan, basically yes, because the proposed Hyperloop run starts well north of LA and will end in the East Bay. So you’d have to add in car time at both ends.
w.
For a meaningful reduction in travel time, autonomous aircraft are the ticket. A helicopter from your house to your destination would be most convenient, but slower in transit. A fixed wing AA would fly faster, but unless you live on an airstrip, you’d have to drive before or after flying.
The software for an autonomous helicopter already exists:
http://heli.stanford.edu/
Range might be an issue for a fast light helicopter. It’s about 382 miles from LA to SF. But 150 mph should be possible, for flight time of ~2.5 hours, with convenience of taking off and landing precisely where desired.
Flight time could be really short for a small jet or twin engine prop plane, but the price tag might be too high for private use. A company however could own one or a fleet. Cruise speed of Mach 0.9 is possible, but cost and range could be an issue. A one-seater capable of 220 mph however might cost only 150 grand, and get good “mileage”.
http://www.dailymail.co.uk/sciencetech/article-3071919/Would-SELF-FLYING-JET-Google-boss-sets-sights-developing-autonomous-plane.html
All the vacuum Hyperloop will ever require can be generated by connecting one end of the tube to the Tesla cash-flow machine. Talk about some serious negative suck!
Is the hyperloop’s capacity really an issue?
The paper Michael Kelly linked to says has a much lower hourly capacity than you calculate and states: The capacity would be on average 840 passengers per hour which is more than sufficient to transport all of the 6 million passengers traveling between Los Angeles and San Francisco areas per year.
I’m not sure about that claim of all passengers travelling is only six million per year, but 840/hour gives around 20,000 per day assuming a 24 hour day. That seems to be comparable to Southwest’s daily capacity from the Bay Area to LA area, ~28,000 (198 flights x 143 passengers/737): https://www.southwest.com/thmpg/flights-from-SFO-to-LAX.html
Caltrans seems to give average daily traffic for I5 around 38,000 in Kern county (as an example of the middle two lane (each way) portion). http://www.dot.ca.gov/trafficops/census/volumes2016/Route5-6.html
So it’s seems its daily capacity is roughly in-line with existing transportation options.
Willis – re the collapsed tank car. I believe that was done by Mythbusters in their final season, and they had a heck of a time with it.. Their first try, they steam cleaned the car, sealed it up while hot, then sprayed it with water to simulate a rainstorm after a cleaning and ill advised sealing. The tanker didn’t collapse. The tried again with an older, rusted tanker. The tanker didn’t collapse. They finally dropped a five ton block of concrete to dent the tank. Only then were they able to collapse it. There’s a description at http://www.thetvaddict.com/2016/01/16/mythbusters-recap-tanker-implosion-crushed/
Maybe 1 inch steel for the tube is enough. (and maybe not).
yes the collapsed tanker is a horible red herring. They are built to hold up agaainst a positive internal pressure
Red herring? Not. The only difference between the Hyperloop tube and the tanker is the thickness of the steel.
The Hyperloop is 1″ thick and the tanker steel is about 12 mm thick, just under half. Other than that they are the same situation, a steel cylinder. Claiming the Hyperloop tube can’t collapse under atmospheric pressure? Because the steel is thicker, it won’t collapse just under atmospheric pressure alone … unless it is kinked, or bent, or damaged in some way. but there are lots of ways that it could get kinked or bent, and then, game over.
In addition, a tank car doesn’t have a fifteen-tonne pod moving through it at 760 mph …
Can all of this be accounted for and engineered for?
Some yes … others, no.
How do you plan to account for earthquakes, for example? Mosh, are you willing to bet your life that a 1″ steel tube won’t collapse under atmospheric pressure, ten tonnes per square metre over the entire pipe surface, in an earthquake?
Pod is going 760 mph, if the quake shifts a pylon an inch or two w.r.t. another pylon, you gonna guarantee the tube won’t fail? Me, I wouldn’t bet on that one … and in California the earthquake question isn’t IF, it is WHEN …
Best regards,
w.
looks like you didnt read.
pylons have xy dampers
and z dampers.
you can bet the engineers do more than speculate using tankers as models of what could happen.
and yes the internal structure of the tube is different. its not purely thickness.
This project will not be affordable for the middle class. The infrastructure cost is an order of magnitude higher than aviation infrastructure. He can’t move enough passengers through the system to spread the cost of the system, over millions of passengers per month, so the tickets will be higher than airfare. And he is still going to need the same TSA hassles that make flying a wait-in-line experience. It has no advantages over flying. You can’t put the terminals in the city, or you will gridlock the city streets, with passengers trying to get in and out of the terminal.
And the final nail could be an increase in speed limit for automated cars. An automated car could certainly drive safely at over 100mph in the left lane of an expressway. That brings the time to drive under 4 hours.
You can overcome a problem or two, when you have no competition in the space you are trying to fill. This project has a very limited customer base, and huge start-up cost. And the rest of the country will not be riding it, so we are all going to vote for not funding it. CA has a lot of voters, but they are not going to get support from the other 49 states. LA and SFO may not even be in the same state, in 15 years!
I don’t think the car speed limit is the issue on I5, there tend to be three problems on I5 in the middle 2-lane sections.
1) Trucks overtaking other trucks, causing the left lane to slow down to ~55mph
2) Drivers flying down the empty right line behind the truck being overtaken and cutting into the already compressed car traffic backed up behind the overtaking truck (from 1) causing others to break and slow even more.
3) Drivers that stick in the left lane, next to, and at the same (slow) speed as the vehicle in the right lane, thus blocking the freeway for everyone else wanting to go faster.
Maybe spending serious money on driver education and enforcement would actually allow a higher speed limit and cut the driving time.
The solution is to have the driving skills designed into the vehicle. The expressways could handle vastly more capacity than it does now, if the system was designed for max throughput. If we are willing to give up control, you will see a vastly different expressway system 20 years from now. Most of it is doable with today’s technology. It just needs to have a critical mass of vehicles that can take advantage of the system, and the desire to save time and money by not sitting in traffic jams.
Absolutely correct, and applies to almost all I-Slabs.
Keep the trucks in the far right lane, which is the rule in some parts of Europa. Capacity and safety would make step-change improvements.
Or, make two lanes for trucks and two others for not trucks.
The claim from the doc Michael Kelly linked is:
The total cost of Hyperloop is under $6 billion USD for two one-way tubes and 40 capsules. Amortizing this capital cost over 20 years and adding daily operational costs gives a total of $20 USD plus operating costs per one-way ticket on the passenger Hyperloop.
So only $20!! Easily affordable for the middle class.
As a cost comparison, the new east span of the Bay Bridge was $6.5 billion for 3km, so that $6 billion for a 500+km project looks somewhat optimistic.
If you want those structures to withstand a 7.0+ earthquake without collapsing it is going to cost 5x that much. Even at that cost there will be substantial damage, from the earthquake that is going to happen. There needs to be a footing dug out, and poured. Then an earthquake force distributing attachment to the ground for everyone of those structures Then they need to keep the tube level, over un-even ground for miles at a time. And we are talking CA labor prices. $6 billion might not even get out of LA county.