I always come to these hyperloop criticisms expecting to find some sort of fatal flaw in the physics of energy efficient supersonic travel. But to my surprise, they instead tend to be pessimists saying things like, "You'll never get past my friends: the regulators, the government bureaucrats, and especially the lawyers!. We will drive up your costs and make you look foolish".
First, no one said that designing this thing in the USA means it has to be deployed in the USA. Countries without common law legal systems get around these unnecessary costs much easier.
Second, if these are seriously the only objections, then thank god we are actually building this thing. I could see complaints if it were some $100 billion publicly funded project, but the fact that less than $1 billion in private capital has already gone so far into demonstrating the technological feasibility of such an innovative transportation mechanism is a huge win.
Maybe in elementary school people should get high marks for effort. I don't know.
But in the case of a company raising funding and claiming it wants to build a ton of subsidized infrastructure to service the public, it isn't the case that we should say, "This is better than some more vacuous application of the money." Because it's not at all clear that Hyperloop is actually a good plan to reintroduce high speed rail into America when so many problems keep coming to light about it.
Then you'll be glad to know that's what he's doing with Hyperloop - he has just released the idea as a paper, but he's not directly involved in its development, which is being done by independent companies.
Dozens of engineers from Tesla and SpaceX contributed in the Hyperloop whitepaper. Plus Elon considers himself an engineer, even though he has a degree in physics.
Reading through the criticisms the consensus is "sure, this can work if you allocate 10-100x more money than estimated." I'm not sure if it's truly innovative if it costs more, places considerable stress (up to 0.5g!) on the rider/cargo (what the author calls a "barf ride"). The analysis picks apart the touted benefits of additional speed when ultimately the capacity is lower and it takes longer to depart. In the case of cargo, the author argues that the "last mile" of cargo takes the longest, and as such there's little benefit to sending it at 1200kph if it then needs to be offloaded and trucked around anyways.
To summarize:
- construction costs are underestimated or completely wrong
- capacity is lower than standard HSR
- Hyperloop claims power usage is higher for HSR than it actually is
- forces aren't adequately accounted for even with canting
- assuming perfect canting the pylons must take the additional force
- the majority of travel time is to/from the station + security screening.
To me, it seems like it's optimizing for the wrong section of the trip.
I think the biggest point the article makes is the great deal of care that needs to be taken in packing loads to meet weight requirements and avoid movement of goods in transit.
What makes sense for international air mail doesn't make sense for a four hour journey by truck, especially if that truck can take a container straight from the ship to the city depot without carefully repacking everything, or go door to door with smaller loads.
Yes. With what exactly does freight-hyperloop try to compete? Trucks are more flexible while freight rail is struggling on most routes and speed seems of least concern there.
Maybe I'm totally unaware, but don't trucking, air freight and sea freight have the same problems w/ regards to weight requirements and movement of goods in transit? Is this not a solved problem? Build Hyperloop Freight to fit a ULD and we're all set no?
Container ships will have a dozen plus containers loaded across. Even if all the cargo shifted to one side of each container, the general balance of the vessel would remain roughly the same.
As the article notes, goods would move a lot more when they're subjected to the G-forces of a hyperloop than the occasional rolling of a ship or even much milder G-forces of an aircraft taking off, which they have to be packed pretty carefully for as is. And whilst all transport methods have a weight limit and some degree of load-balancing requirement, it's much more of a restriction for the load of a capsule fired at supersonic speed through a curving tube that has to resist forces imposed upon it than a bigger lorry chugging along at a sedate 60mph.
The issue is not acceleration front/back, which can be dealt with in design and is fairly stable and consistent, but acceleration as much as 0.5G side/side, which is also more intermittent and against which it's difficult to build seats that would protect customers.
Really it's just a question of track design as these are 100% predictable G forces. If you really need to turn you can just roll the cabin and keep these g's directly under you and or slow down apraoching it. Elevators can also quickly have a fairly wide range (0.8 to 1.2) g's and people don't really get sick in them.
Aeroplanes are probably a more accurate approximation of what you'd feel. You get hardly any G force from banked highways, your speed is just too low. Now I don't really get plane sick, I will quite happily sit through a few barrel rolls (which is far more extreme than the hyperloop (although that would be fun)), but there's plenty of people who would get sick from a few 1.5 G banked turns.
Elevators are different because you don't spend more than about 1 minute in an elevator.
High end cars can pull up to 1g lateral forces and many cars can pull up to 1g breaking on a good road surface. Relatively low top speed just means you don't accelerate very long. I have hit weightlessness over a hill at high speeds followed by 1.x g on the other side, so 0.5 g does not seem bad.
What about one where you feel that, acting in various directions, at every curve, every speed transition, and every elevation change. Because that's the "barf ride" being discussed, not merely getting thrown to the back of your seat during initial acceleration.
Although as the poster mentioned below, a passenger service would gradually rotate the passenger compartment to keep the G-forces vertical, a la a banking aircraft, so all you'd likely notice would be feeling heavier for a few seconds.
Interesting link, thanks! I should have clicked more on the original article. :)
This seems to be the comment in question:
> This is worse than sideways acceleration: track standards for vertical acceleration are tighter than for horizontal acceleration, about 0.5-0.67 m/s^2, one tenth to one seventh what Musk wants to subject his passengers to. It’s not transportation; it’s a barf ride.
I find the statement that vertical acceleration is 'worse than sideways acceleration' to be highly suspect (otherwise why would you bother to bank into turns?) - I would guess that the track standards are for +/- 0.5ms^-2 and mostly target short-period up-and-down bouncing motions rather than smoothly applied upwards acceleration.
> Pessimism seems to be the default for the HN hivemind.
At the time of typing this the pessimism has been entirely reasonable and I'd say in the minority, with Xorlev outlining the fundamental issues with Hyperloop (capacity, costs, solving the wrong end of the problem) and KirinDave pointing out how while yes, there are more vacuous ways of spending money, when you're mucking around with other people's dough there's an expectation on return on investment, otherwise it's a charity.
I'd like to see the Hyperloop built just as I'd like all kinds of cool, complex and not necessarily practical technologies develop. But it's not unfair to point out the economic and physical realities that will get in the way of those things.
Nobody here is trying to crush dreams. The author, and many others, are simply trying to point out that there are much better uses of time and money.
The factors (i.e. physics) underpinning the economics of freight shipping in all forms are well understood. Can a hyperloop be built? Sure. Is it better than existing intermodal cargo shipment infrastructure? Yes and no. It certainly offers speed, but doomedly at the expense of economies of scale: https://www.usmma.edu/sites/usmma.edu/files/docs/CMA%20Paper...
Bottom line, if you can find enough high value bulk cargo that benefits significantly from high speed transit to only two or three "ports", then hyperloop is your answer. However, that's a very (perhaps nonexistent) niche in the industry.
What we (transport engineering community) need to be expending resources on is: a.) eliminating greenhouse gas emissions, b.) designing a system of transport that scales with global trade demand (vice building 20K+ TEU megaships that can only be served by a few ports and promote trucking congestion in ports). Autonomous shipping, AI implementations in both freight forwarding (the logistics side) and transport control systems themselves, and applications of H2 fuel cells are technologies with great promise.
Aren't the acceleration figures a criticism of the physics?
Same with the argument about centralization. It's a practical non starter if sticking the load on a truck that just goes to the destination is faster than shifting the load off the truck onto the hyperloop and then back onto a truck.
Maybe there is no single fatal flaw. The point is, though, that there are many, many issues that need to be addressed and it is very clear already now that the hyperloop will be uneconomical. In other words:
It might be possible to force it into existence, but it won't be worth it.
Basically expansion and contraction as well as just plain vulnerability of running a vacuum make it extremely difficult to do practically. The phrase he uses, "all the problems of space travel except in a gun barrel" is a pretty accurate description of the issue. Any loss of vacuum will almost guarantee loss of life. No realistic demo has been done even on a small scale as of yet.
Why would loss of vacuum necessarily result in loss of life? I would expect loss of vacuum to result in sudden deceleration, but not with a deadly level of force.
I don't understand why a tube section couldn't come away? What if a bomb went off, a truck hit a support beam, or an earthquake caused a section to topple over...
It's an elevated track so it really could be designed to deal with that kind of break. Water, Oil, and Gas pipelines for example have long dealt with those issues without breaking when designed correctly.
Now doing this without bending the long pipe is going to be harder, but you really could design this thing so riders don't notice a magnitude 9 earthquake.
PS: In the end you get into cost benefit designing it to survive an aircraft impact is probably not worth it let alone a nuke, but predictable earthquakes are not that hard.
First, you would get choked flow at the inlet, and if you do the math it actually takes a massive opening to really make a dangerous shockwave.
Eg, if a joint in the tube disconnects and the two halves pull apart, the inlet area is the tube circumference * gap between halves. The two halves would need to separate by the full diameter of the tube (~15 ft) to get full atmospheric pressure going in both sides. A realistic gap of a couple inches to a couple feet is far less scary.
Second, these incidents will be exceptionally rare. Gaps that big are equivalent to a freeway overpass collapsing. It's a total failure scenario, so you see a single digit number of them a year in the US.
Lastly, the speed of sound isn't all that quick on the scale of this thing. It's about 13 miles/min, a fifth of a mile a second.
If you place emergency fill valves (one time use things, dirt cheap, just explosive bolts in the simplest case) you can flood a whole section of the tube with atmosphere in a controlled manner over say 15 seconds, and your shockwave will be largely stopped after 3 miles.
An emergency fill like that would also stop all pods in the region as they hit very high drag, so you don't even need to carry heavy emergency brakes on every vehicle.
Seems like you could also solve this with blast gates. If the tube breaks open behind the train, slam a gate closed to stop additional air from entering. There'd likely be air in the tube already, but with no additional supply, the propellant force would diminish rapidly.
Okay, I was assuming a failure in front of the train. If the failure is behind the train, it's still an extremely solvable problem. Blast gates to stop the inflow of new air. Or inject air in front as nickparker suggested. I don't see that this is a legitimate blocker to this technology.
This is a hollow answer. "Not designed for" is an absurd claim for a thing still in prototyping. Same for the "explosive recompression" claim. You're making this claim about a system that doesn't exist.
I'm not bullish on hyperloop but I see no reason to believe that the engineers can't design a pod capable of not disintegrating in air, or capable of designing a track with a failure mode better than completely falling apart.
You assume that Hyperloop's tube will run a vacuum, which is a misconception. The Hyperloop One design uses low pressure tubes which is completely different from being completely evacuated.
Vacuum doesn't exist for all practical purposes, every form of vacuum is just low pressure. So if you don't say anything about what level of vacuum or how low the pressure is your statement is meaningless.
Ahh yes, the infamous Thunderf00t "debunking" video. Never have so many Hyperloop myths been created by a single piece of content! I've debunked-the-debunking a half dozen times myself, and it shows no signs of slowing down.
The big problem with his air cannon theory is, pipes are not lossless! Friction and viscous interactions between the entering air and the tube wall will slow down that "shock front" to a highway speed wind in only a couple km. So unless it's so close that the pod can't stop in time (and actually derails at the breach), there should be no loss of life.
As far as thermal expansion, that can be solved with sliding interfaces every few hundred meters. The Hyperloop has switched to mag-lev designs for levitation, so the ultra smooth interior is no longer necessary. There will be some air leakage at the joint of course, but this can easily made up by the pumping stations installed at intervals along the track.
The pressure in the Hyperloop was specifically chosen so that simple mechanical vacuum pumps can be used -- no turbomolecular or cryopumps needed. The Hyperloop runs at 1/1000th of an atmosphere. True "vacuum trains" use vacuums at about 1/1,000,000th of an atmosphere, meaning the pumping is about 1000 times harder (not because the pressure difference is meaningfully different, but because you only get 1/1000th as much air per "stroke" or "cycle").
The Large Hadron Collider uses a harder vacuum still (about 1/1,000,000,000,000 of an atmosphere, and yes that's a trillionth of an atmosphere), which is why LordHumungous's experience mentioned earlier isn't terribly applicable. The LHC is doing something a lot harder than the Hyperloop.
That's a strawman. Most of the criticisms are technological and security related. How do you keep an enormous vacuum tube with fast-moving pods inside secure against even simple attacks?
That will maybe derail one train. Versus the whole tube exploding at the speed of sound and/or the shockwave hitting every pod traveling at speeds designed for near vacuum.
Physics 303: "pipes are not lossless! Friction and viscous interactions between the entering air and the tube wall will slow down that "shock front" to a highway speed wind in only a couple km." (quote from schiffern post). You may want to look at derivatives of Bernoulli's equation, like Darcy–Weisbach equation.
Plus there is a planned emergency repressurization of the whole tube that would eliminate even that medium speed shock front. Plus a small 10cm diameter bullet hole would imply in less than 1% of the flow of a completely broken tube (a much harder feat to do), per laws of conservation of energy and matter.
As pods travel with 4km or so of separation, at most one pod will be affected. That is much less people than a derailed train.
To be fair, Musk's original paper advocating the concept was structured as a criticism of the supposed inefficiency of rail alternatives, and was heavy on deliberate cost underestimates and light on physics. So it's not exactly unreasonable that most critiques start off with the economics.
This critique, however, raises quite specific physics-related logistical reasons why Hyperloop is a ludicrously impractical solution for most forms of freight and uneconomical for the rest. Things it doesn't mention, even implicitly, include regulation, government and lawyers. Perhaps you'd get more out of these hyperloop criticisms if you read them?
so many are using the 'playing at moonshots with other peoples money' criticism.
It's not like investors are blind or dumbstruck just because it's an idea from Musk.
They do their due diligence and if they think the plan has potential, they invest.
I'm sure there were countless technical issues and big challenges around airplanes in the initial stages. And cars. And trains. And, you know, every new technology.
Could Hyperloop (One) fail miserably? Sure. Could it succeed? Also.
Let's just wait and see.
Also, whenever there are invested interests of established competition, they usually drum up the PR machine against new ideas, just as a precaution.
Just look at the fascinating history of fridges vs ice box companies for one of countless examples.
One need look no farther than Silicon Valley to see a plethora of starry eyed investors who are either blind, dumbstruck, or simply haven't done due diligence. Isn't the bubble about to pop... again?
I don't think we are in a bubble anything like the dot com debacle.
The industry as a whole is far more mature now, and paths to monetization are clearer. Competition is high, so is the competence of most VCs and investors.
I'd also place an engineering project like Hyperloop in a whole different space than the typical SV stuff.
"paths to monetization are clearer." Indeed. Try to generate enough hype to bilk IPO investors or failing that get bought out by a firm that actually makes money.
Just now, I read this piece and the linked New York Magazine piece (which, without mentioning regulators, managed to make the whole outfit sound like the kind of scam Hacker News usually delights in outing). I do not see any arguments of the form you're suggesting. It's not the author's friend "the regulators" that are going to make the Hyperloop fail; it's his friends "physics" and "economics".
Statute law systems are the socialism of law, Common-law, this collaborative law making is the 'free market' problem, and it does not have a calculation problem via the legislator/statute marker.
> I always come to these hyperloop criticisms expecting to find some sort of fatal flaw in the physics of energy efficient supersonic travel. But to my surprise, they instead
Except, as the article points out, it's not actually faster, cheaper, or efficient than competing technologies. Those seem like really fatal flaws.
> Countries without common law legal systems get around these unnecessary costs much easier.
That same logic also applies to the competing technologies. The same magic wand that lets you build a hyperloop for 1/10th what it would cost in the US also lets you build the tracks for HSR for 1/10th what it would cost in the US. You can't compare the cost of building a hyperloop in China to the cost of building HSR in California and get a meaningful answer.
Nobody is saying that the hyperloop is impossible; they're saying that it's a plan to build something objectively worse than high speed rail at prices that seem broadly comparable.
I think you are misinterpreting the criticism. There's a difference between "regulator, bureaucrats & lawyers will stop you" with "there is no compelling advantage with this approach.
It's flashy and all to say you're going to break all the rules, but you could just as easily do that with conventional means of transportation.
The author spends the first 2 paragraphs discussing how existing rail and pylon technology wouldn't work for the hyperloop. I find this to be short sighted as it seems entirely reasonable to use different "rail" and "pylon" designs for the hyperloop. Surely engineers might come up with a different solution for a different problem?
Here's an idea: Ditch the vacuum and instead put a mixture of 80% helium and 20% oxygen at half sea level pressure. This way you'll get a breathable atmosphere that is five times less dense than air and causes as much less drag. Imagine Teslas hurtling 155mph through these tunnels using only as much energy as if they were traveling at 85mph.
I don't know, maybe from the 175 million cubic meters produced annually? For a 300km, two lane stretch you'd require around 7.5mln cubic meters - sure, that's a lot, but it's not an impossible amount.
I think GP was asking: how do you get the helium from thousands of wells spread throughout the continent to the pump stations in California? Surely there are some logistical challenges involved in that.
Helium, for the time being, is a non-renewable resource, and there are concerns of a helium shortage for important applications like cryogenics. It is probably not a good idea to use helium as you suggested.
So almost 5% of global production of Helium? Add to that the fact that helium tends to leak at a much higher rate than any gas, and that sounds prohibitively expensive.
Especially since the current price of Helium is artificially low, and it's not a renewable resource at current extraction rates, so the price is not going to remain so low in the future.
I had thought the concept for hyper loop was that the infrastructure cost would be cheaper because it is a tube that does not require power or rails.
But it does seem like saying instead of two rails that allow for deviations both horizontally and vertically and the vehicle stays on top, then now we need a really nicely round tube with a different set of requirements that must be maintained over hundreds or thousands of miles.
I guess if hyperloop teams are still in the phase of proving stuff out and they need money then the money they will get will still probably be tiny compared to what it would cost to actually build a real full blown system when you factor in all of the costs of buying land and permits and construction companies.
When people talk about using high speed rail in the US and talk about how it doesn't work, I think the problem is exemplified by how any rail system seems to get implemented in the US. Basically what I have seen in virtually all cities around the US that I've traveled, the train goes close to downtown or close to the airport, but not actually into the actual terminal in the airport. Or you have a fast train that drops you in some place where you have to transfer to something else like a taxi or bus or another train. For example as I understand it, the new high speed train in California in the SF area will not realistically be any better than riding Caltrain. So since it likely will cost more than Caltrain a big base of people who could be riding it everyday to get between SF and San Jose would not be using it. And I think it stops in like a far flung spot in San Jose probably far away from many people's jobs. So it's like, well may as well just keep taking Caltrain!
the goal of high speed rail project in California is not taking you from SF to SJ. it's the bay area to LA area. this is not a train for within Bay Area commuters
Caltrain with express trains works very well. sfo and oak have trains that go into the airport. caltrains goal of electrification if it ever happens should make SF to SJ a lot faster. trains in the Bay Area are not as bad as you make them out to be.
personally I think high speed rail should go from Santa Clarita to gilroy or south San Jose. once you pass up the Central Valley you can take bart or Caltrain to your final destination
Yea I understand that the goal of the california HSR is to get you from SF to LA in its current form, but I guess what I'm getting at is that these systems become much more viable when they truly get you from point A to point B for commuters extremely quickly -- ridership goes way up. If it takes you 30 mins to get someplace that previously took an hour or more, then taking that small transfer seems like a small burden to add onto that. So at least if part of your trip is at very high speed that is extremely helpful, and focuses additional density desires for people who want to move there or build houses. For example, the Taiwan HSR can get you from Taipei downtown to Hsinchu in around 45 mins, and its around the same distance between SF and San Jose -- 50-ish miles. The baby bullet assuming you can actually catch one will take around 1.5 hours to get from SF to San Jose. In Taipei, driving to Hsinchu vs taking the HSR is kind of ridiculous because you hit so much traffic just trying to get out of the city and then the toll roads along the way can be backed up at various points.. so the result is that if you can take the HSR, a large percentage of people do take it. BTW to get that 45 minute time between Taipei and Hsinchu, it stops at I think 2-3 stops along the way. So, you could have SF downtown, SFO, maybe Redwood City, Mountain View, and then San Jose. I mean these trains can go 170 miles per hour and they only take a couple of minutes to get up to around 130 mph, so its not like they need to have zero stops. But I guess if a 1.5 hour commute vs. 45 min commute people don't care too much about, then HSR is not really that useful, but I do think people would really want that. The HSR in the SF peninsula area as far as I know will not go much faster than any trains on that same corridor right now for a variety of reasons. So basically what we really need is a totally new corridor that separates grade such as elevated or underground in order to get the speeds and safety.
There are very few high-speed lines in the world that are primarily concerned with commuting over ~50 miles; very few have stops that close together, even, if we look at anything going over ~150mph.
At this point Hyperloop would have to support Intermodal freight transport to even have a chance. The technical limitations of container ships or the containers themselves would need to be considered. Hard to be beat taking a container off a ship and dropping it right onto a train car.
Of all the hyped up startups out there. I'm personally most bullish on the promise of the Hyperloop. Really Hyperloop One since they're the only one making actual progress.
The article makes some decent sounding criticism on the issue of last mile being the limiting factor. But it all reminds me of what I heard before regarding fast internet connectivity (the issue of the last mile), or why would people need personal computers. The problem with criticizing anything that can impact the future, is that we just don't know how it'll impact it.
I do know that anytime transportation or means of connecting goods or people has been changed, it has had tremendous impact in economy and how the world works.
Do we need to ship cargo at 500 MPH? With today's thinking, maybe no. But I do know by building and experimenting with Hyperloop not only we might just transform the world, in the process will probably make other accidental discoveries as an added bonus.
Seems like this is something a company like Amazon could be interested in, for the long tail of products it might be more cost effective to be able to ship via hyperloop vs building more capacity.
Why not, instead of using an almost-vacuum and a separate means of propulsion, create a stream of air similar to that of bank tubes and just use that for propulsion?
Fans inside of the tube would pull air in the direction of travel, and it could be circulated or pumped in from / out to the outside at the ends. At the end of the tubes a main fan system would be the primary work horse, creating vacuum forces on the arrival end and pushing forces on the departure end.
In the last mile, the fan system could shut down and use the pressure to help stop the vehicle and even store some of the pressure to help start the system in the opposite direction later (i.e., regenerative breaking).
Instead of the air resistance of a train-sized object (about a quarter mile long) you'd have air resistance equivalent to a train 300 miles long (think of the tunnel as an inside out train). It's inefficient by several orders of magnitude.
Wait, if the walls were made to be near frictionless, then the aggregate energy, minus what's lost to hear from turbulence, would be used for motion, right?
What I mean is that the energy wouldn't be lost. The turbulence wouldn't result in a net loss of energy, except that which was lost as heat through the walls (a 1cm layer of vacuum would insulate against that).
Totally wrong. All of that turbulence goes into heat, which must be sunk through the walls (or something else), and is therefore lost. "Fully turbulent flow" is a reference to the transition away from (low-friction) laminar flow. Flow gets to be fully turbulent by experiencing high internal fluid friction due to its own viscosity. Air's viscosity is low relative to water, but it still isn't zero. 500 mph flow through a big long tube is extremely lossy.
Yawn. Freight has much bigger problems, like, in the US you have the Jones act, which essentially means freight from foreign countries gets bulk broken at a small number of ports instead of more directly moved to the ports it should go to.
See, e.g., https://en.wikipedia.org/wiki/Merchant_Marine_Act_of_1920#Ef...
Put all the passengers on the hyper loop, build a freight-only rail beneath the hyper loop, which can be more efficient because it no longer needs to consider passenger requirements with regards to noise, width, height, or even atmosphere in tunnels.
Hyperloop may be an unmitigated disaster. But the effort has clear benefits.
An innovative solution to shifting loads would be immediately useful to air freight, and probably trucking and shipping.
Some solution to the sudden loss of vacuum would be useful in everything from oil pipelines to freeway traffic. Turning the wall of air into a smooth gradient in seconds is perhaps impossible, but even a partial solution would create a whole host of companies to take advantage of the new technique.
New materials developed for the pylons, and techniques for manufacturing those pylons are likely broadly applicable. Bridges are of course an obvious example.
Does every flaw with the hyperloop require science fiction? Or is it just out of reach?
It seems like the Department of Transportation should provide a whole bunch of grad students money to answer the questions, rather than private investors, because those problems sound very big and very risky to me. But if they think they can do it, why not go for it?
One thing the article misses is inflexibility. One of the big disadvantages of rail is that once the track is deployed it is very costly and difficult to upgrade it. One thing I'd want in any "futuristic" freight hauling method would be ease of scaling I don't think Hyperloop offers anything over rail in this regard once track is installed you are more or less stuck with the installed capacity forever.
A computer analogy I'd give is to think of freight handling like information communication - the big issues are bandwidth (How much can you send/receive in one shipment) latency (How long does it take to arrive) and throughput (How many shipments can you handle at once).
Hyperloop addresses the latency issue but does little to nothing to address the other two problems
From what I see working in a heavy industry which relies on bulk freight (for import and export). Throughput (i.e Congestion) is the hot issue - we have a rail terminal and a deep water berth (which handles capesized ships). The rail corridor is shared and at times pretty heavily congested we use road trains (b-double trucks) to make up for the shortfall.
> A computer analogy I'd give is to think of freight handling like information communication
Unsurprisingly, a lot of the theory for transport networks maps extremely well to computer networks.
Transport is essentially a literal packet switched network. You have routers (depots), routes (roads, rails, etc), packets (in many cases, literally packets), MTUs (twenty foot containers, or truckloads).
Queuing theory equally applies to both as well (and a lot of other physical applications, at university we had an exercise applying it to customer support).
I remember talks of propping up underground rails as internet of things, literally pushing things instead of data toward any place automatically. I'd love to test this.
Anecdotally one of my Engineering lecturers at university was an expert on human logistics. (i.e the physical queuing of people) I remember talking to her about a project she was working on with a large retail chain advising them on how to funnel people through store checkouts more efficiently.
Well the article's author could have put more emphasize on the inflexibility, but reading the Parts on airfreight and trucks I think he got the gist of it. Good read.
Concerning "barf rides": wouldn't Strong and well-timed anesthetics help?
Uhhh, no. Anesthesia is rather dangerous. It's unsafe without medical supervision, which means it just shunts the costs from passengers to the anesthesiologists that'd have to accompany them.
Of course the hyperloop is a joke. Elon Musk has zero experience or training in transportation infrastructure, but we are supposed to have faith in some idea he farted out in a white paper, why? Because he has skillfully cultivated his image as a "genius", and we bought it? The hyperloop was nothing more than a (savvy) PR move to cement his image as a "visionary". That it actually got funded only goes to show what gullible shmucks some venture capitalists are.
Edit: I worked on the LHC for several years. The challenges of maintaining a closed vacuum pipe that spanned a mere 17 miles were vast and expensive. Musk proposes doing it on an exponentially larger scale without addressing the challenges and pitfalls involved. Until he does so, I cannot take him seriously.
The tolerances on each part must be very tight. If there is a single flaw in one part, the whole vacuum fails. The challenges become exponentially greater as you scale up the diameter of the pipe, since the force on the pipe is proportional to the square of the radius. The LHC had a 50mm diameter pipe, the hyperloop proposes an 8+ foot diameter. You do the math.
The Hyperloop will operate at about 15 psi pressure differential maximum (i.e., one atmosphere).
The Alaska Pipeline is certified to operate at 1,180 psi.
It's not a problem, and minor leaks are not a problem, either. A leak that would stop a particle accelerator dead in its tracks will just make a hyperloop operate at slightly lower efficiency. Plus you can always just run the pump (any practical design will doubtless have the pumps running continously to make up for leakage, just as many ships and buildings have continuously-running bilge and sump pumps).
My personal opinion is not that it can't be done, but that it's financially impractical given then huge maintenance costs compared to conventional high speed rail system.
When you said that you worked on the LHC for several years - what was your role, and how were you involved with the vacuum system? Because your answers show a serious lack of understanding.
First, part tolerances are not a particularly important issue with engineering of high vacuum systems (sealing is effected by compression of gaskets, usually soft stainless steel gaskets for UHV systems).
Secondly, the difficulties in maintaining a large UHV system is usually related to "outgassing", from multiple surfaces and/or material imperfections, and are rarely due to "a single flaw in one part".
Thirdly, you are using the word "exponentially" wrong, even in the context of your flawed claim which is addressed below.
Finally: "the force on the pipe" is not, in a meaningful sense, proportional to the square of the radius. The forces in the pipe wall are proportional directly to the radius (formula is stress=pressure*radius/thickness), if it was otherwise pipe thickness would grow as the square of diameter and large pressurised pipes would be physically impossible.
Happy to do the math for you when you need it, best to leave it to the experts.
Just FYI - hoop stress as you've quoted it assumes a thin walled cylinder. I haven't worked on the LHC so don't know the dimensions; however, this assumption is really only valid for D/t > 20 or so before solutions diverge at which point the interaction becomes more complex than R/t.
Regarding your first point: from my experience (working on physics experiments that depend on vacuum <10^-11 torr), the construction of the knife edge that seals against the gasket is fairly important - any chips or imperfections and the part is garbage. Also do people really use stainless for gaskets? I've always used (and seen other people use) copper, stainless sounds like a huge pain to torque down on.
I doubt UHV experience is relevant here though - at 100 torr you can probably get away with simple o-ring seals. And outgassing doesn't matter: even isopropanol has a vapor pressure of only 40 torr.
Edit: The hyperloop design is at ~1 torr, not 100. Still, I'd imagine outgassing is not a huge issue.
"The challenges of maintaining a closed vacuum pipe that spanned a mere 17 miles were vast and expensive."
The vacuum level required for a particle accelerator (10^-11 torr or something like that) and the one posited for the Hyperloop (0.75 torr) are so far apart that they have virtually nothing in common.
That is actually a valid point, Musk only proposes a partial vacuum which is a lot different from a pure vacuum. However, I think that is still a lot to ask for heavily used transit infrastructure.
Elon Musk had zero experience building cars, yet he made Tesla happen. Perhaps a high intellect and a good general purpose engineering training can accomplish more than you think.
You, on the other hand, are overwhelmed by the challenge of maintaining vacuum in a tube that spans a mere 17 miles. At the very least, you should restrain yourself from using language like "...some idea he farted out...".
Given that the Hyperloop is failing spectacularly, "a high intellect and a good general purpose engineering training" seem empirically to not accomplish quite as much as you think they do -- although, in fairness to high intellect and good general purpose engineering training, there was never any real reason to think that they'd be able to accomplish magic.
1) Elon Musk is not building any Hyperloop, so I don't see how its supposed failure reflects on him.
2) Which Hyperloop is failing? There are at least three groups, and as far as I know, they haven't even got close to testing the system, let alone know if it's a failure or not.
I'm skeptical of the whole concept, but declaring failure at this stage is no less silly than assuming it'll definitively work.
Yes... it clearly is a manageable issue. The opening comment writer was the one who was overwhelmed, and no surprise given his lack of understanding demonstrated in his answer elsewhere. I just hate it when people with such a lack of knowledge make rude, hateful remarks.
Hmm, that person "worked on the LHC for several years" so they might know a couple of things about long evacuated tubes. Unless I'm not following the thread very well. Shrug.
be careful, tesla is not successful as a car company yet, and its not in good shape to become one either.
one day it might be, and more generally i do hope that we see more progress in the electric car world... but for now tesla only turns a profit as a car company coupled with government incentives. even then, outside of the US (and inside actually) their market share is tiny or zero with very little growth. saying that it doesn't even exist is a very good approximation to reality... if you ignore tech focused news articles and the like at least.
i wouldn't call that a success just yet... as much as we may admire the mission.
In terms of their mission statement which is convince people that electric cars can be 'cool', practical and inexpensive he has succeeded much more than you are giving him and the people at Tesla credit for.
If I take your first paragraph and replace Hyperloop with Space X, it sounds like something one could have said back when that started. Yet here we are.
I'm no expert either, but that sounds rather hollow..
SpaceX's success is largely due to not having to perform all the hard R&D of rocketry up-front. They got that done for them, for free, by major governments in the 50s and 60s. So now SpaceX can simply build off that, making evolutionary rather than revolutionary changes to the technology and turning it into a profitable business.
But Hyperloop is unexplored territory. There isn't billions/trillions of fundamental R&D already done and given away for free by somebody else. I suspect that's going to have an impact.
Hyperloop can leverage trillion in highly relevant fundamental R&D also. For example aircraft already operate at low enough external pressure to quickly kill the passengers ex: concord was under 1/20th ATM. Yet, loss of cabin pressure is a very rare situation. There is a lot of proven technology to maintain low vacuum cheaply, as a first step to achieving high vacuum. Massively improved battery technology enables reasonably high energy density's which are very much necessary. etc.
Now, sure there is a lot of new tech that would be needed. But, less than you might think.
Vactrains might work out. There's nothing wrong with maglev in an evacuated tube. A system where the thing runs on open track until it gets out of the city and can switch to a vacuum tube might work. Then you can get someplace useful. Most of the "hyperloop" proposals, including the MIT demo, are really maglev vactrains.
If you're already a maglev, a tube doesn't add much. Japan's maglev has already reached 600 Km/h. The Shanghai/Transrapid maglev routinely runs at 431 Km/h, and has hit 500 in tests. At those speeds, SF-LA is about an hour. But the track cost is very high.
That's not stopping JR Tokai. The Tokyo to Nagoya maglev line has been under construction for two years now. They're taking the most direct route to get the fastest transit time. There are mountain ranges in the way. They're going straight through them. 90% in tunnel. Completion in 2027. Cost comparable to Twitter's peak market cap. Public support for this is so high that JR is being pushed to build the next section, Nagoya to Osaka, sooner.
>But the track cost is very high. That's not stopping JR Tokai.
It all depends on perspective. If decision maker view the maglev as the 21st century version of the railway that let societies prosper in the 19th and 20th, then it might not be expensive at all because the return is so great and the horizon so long.
Hypothetically, the vacuum tube gives you energy efficiency.
Drag power is proportional to the cube of velocity, so drag energy losses over a fixed distance are proportional to the square.
In an ideal world you're paying a fixed cost per unit time to pump the tube down then you shove as much stuff as you can through it at transsonic speed, catch it all with regenerative brakes at the other end, and pay an energy per kg payload cost lower than electric road vehicles.
Of course in practice that fixed cost may turn out astronomically high, but that's the idea.
Presumably with all existing systems it has been much, much more cost effective to be aerodynamic rather than building/maintaining/decompressing the worlds largest vacuum tube
Note the main way in which the JR Maglev will allow adding speed is by building a very straight line for a lot of money, which could benefit conventional rail just as well.
an expert in logistics asked “why do we need to move cargo at 500 mph?“. The problem is one of face.
I guess the 18,000 packages per hour that arrive at ANC by jet must also be a matter of "face"?
What does this even mean?
Edit for clarity: The FedEx terminal at Ted Stevens Anchorage International Airport can handle 13,400 packages per hour. The UPS terminal there handles about 5,000 packages per hour. Virtually all of these packages arrive from Asia on jets traveling hundreds of miles per hour (as opposed to the alternative, container ships, which are cheaper, but much slower).
That's because Anchorage is the major airport that's closest to being on a great circle route between North America and Asia. Most of the packages clear customs in Anchorage, and are then fed into the FedEx and UPS systems for further distribution throughout North America.
Clearly there is a very large market for moving cargo at 500 miles per hour. Frankly, I have a hard time believing that an "expert in logistics" would make such a statement.
Freight networks are critical and hyperloop has a claim to high efficiency transport. This might not work out as hoped but it is most certainly not a joke.
i still think there is a much bigger problem in simply getting the thing through the red tape necessary too... even if it was useful, it would be a real struggle to be allowed to operate at all imo...
"This is actually worse for freight than for passengers, which is why the speed limits on curves are lower for freight trains than for passenger trains"
I'm 91% sure that this is less to do with freight specifically and more to do with the amount of weight involved and how it's distributed in each car. Then again, I'm no expert on freight trains.
What I find annoying about this "hyperloop" hype is that it's just a rehash of the concept of a vactrain, but because Musk wrote it is suddenly genius and visionary (https://en.m.wikipedia.org/wiki/Vactrain).
176 comments
[ 3.5 ms ] story [ 112 ms ] threadFirst, no one said that designing this thing in the USA means it has to be deployed in the USA. Countries without common law legal systems get around these unnecessary costs much easier.
Second, if these are seriously the only objections, then thank god we are actually building this thing. I could see complaints if it were some $100 billion publicly funded project, but the fact that less than $1 billion in private capital has already gone so far into demonstrating the technological feasibility of such an innovative transportation mechanism is a huge win.
But in the case of a company raising funding and claiming it wants to build a ton of subsidized infrastructure to service the public, it isn't the case that we should say, "This is better than some more vacuous application of the money." Because it's not at all clear that Hyperloop is actually a good plan to reintroduce high speed rail into America when so many problems keep coming to light about it.
To summarize:
- construction costs are underestimated or completely wrong
- capacity is lower than standard HSR
- Hyperloop claims power usage is higher for HSR than it actually is
- forces aren't adequately accounted for even with canting
- assuming perfect canting the pylons must take the additional force
- the majority of travel time is to/from the station + security screening.
To me, it seems like it's optimizing for the wrong section of the trip.
What makes sense for international air mail doesn't make sense for a four hour journey by truck, especially if that truck can take a container straight from the ship to the city depot without carefully repacking everything, or go door to door with smaller loads.
Highways for example have fairly wide banks which people rarely notice. https://sterlingpearce.files.wordpress.com/2015/02/img_0054....
Elevators are different because you don't spend more than about 1 minute in an elevator.
Remember 1g * 1 second is only ~22mph.
The problem is when it's sustained. That's why people get sick on roller coasters and when doing aerobatics (extreme examples, I know).
Although as the poster mentioned below, a passenger service would gradually rotate the passenger compartment to keep the G-forces vertical, a la a banking aircraft, so all you'd likely notice would be feeling heavier for a few seconds.
See https://pedestrianobservations.wordpress.com/2013/08/13/loop... linked from the original article.
This seems to be the comment in question:
> This is worse than sideways acceleration: track standards for vertical acceleration are tighter than for horizontal acceleration, about 0.5-0.67 m/s^2, one tenth to one seventh what Musk wants to subject his passengers to. It’s not transportation; it’s a barf ride.
I find the statement that vertical acceleration is 'worse than sideways acceleration' to be highly suspect (otherwise why would you bother to bank into turns?) - I would guess that the track standards are for +/- 0.5ms^-2 and mostly target short-period up-and-down bouncing motions rather than smoothly applied upwards acceleration.
At the time of typing this the pessimism has been entirely reasonable and I'd say in the minority, with Xorlev outlining the fundamental issues with Hyperloop (capacity, costs, solving the wrong end of the problem) and KirinDave pointing out how while yes, there are more vacuous ways of spending money, when you're mucking around with other people's dough there's an expectation on return on investment, otherwise it's a charity.
I'd like to see the Hyperloop built just as I'd like all kinds of cool, complex and not necessarily practical technologies develop. But it's not unfair to point out the economic and physical realities that will get in the way of those things.
The factors (i.e. physics) underpinning the economics of freight shipping in all forms are well understood. Can a hyperloop be built? Sure. Is it better than existing intermodal cargo shipment infrastructure? Yes and no. It certainly offers speed, but doomedly at the expense of economies of scale: https://www.usmma.edu/sites/usmma.edu/files/docs/CMA%20Paper...
Here's a thoughtful assessment by Olaf Merk posted last month that draws the same conclusion as the author: http://shippingtoday.eu/musk_maritime/
Bottom line, if you can find enough high value bulk cargo that benefits significantly from high speed transit to only two or three "ports", then hyperloop is your answer. However, that's a very (perhaps nonexistent) niche in the industry.
What we (transport engineering community) need to be expending resources on is: a.) eliminating greenhouse gas emissions, b.) designing a system of transport that scales with global trade demand (vice building 20K+ TEU megaships that can only be served by a few ports and promote trucking congestion in ports). Autonomous shipping, AI implementations in both freight forwarding (the logistics side) and transport control systems themselves, and applications of H2 fuel cells are technologies with great promise.
Positive thinking never solved anything.
Same with the argument about centralization. It's a practical non starter if sticking the load on a truck that just goes to the destination is faster than shifting the load off the truck onto the hyperloop and then back onto a truck.
It might be possible to force it into existence, but it won't be worth it.
Basically expansion and contraction as well as just plain vulnerability of running a vacuum make it extremely difficult to do practically. The phrase he uses, "all the problems of space travel except in a gun barrel" is a pretty accurate description of the issue. Any loss of vacuum will almost guarantee loss of life. No realistic demo has been done even on a small scale as of yet.
I don't think it is unrealistic at all.
See: http://whns.images.worldnow.com/images/22787728_SA.jpg
Sliders https://www.quora.com/Why-do-oil-pipelines-that-transfer-oil...
Now doing this without bending the long pipe is going to be harder, but you really could design this thing so riders don't notice a magnitude 9 earthquake.
PS: In the end you get into cost benefit designing it to survive an aircraft impact is probably not worth it let alone a nuke, but predictable earthquakes are not that hard.
My wife was PM on an emergency project to replace a 72" main feeding a city that failed.
My wife was PM on an emergency project to replace a 72" main feeding a city that failed.
http://www.snopes.com/photos/accident/graphics/gasline2.jpg
First, you would get choked flow at the inlet, and if you do the math it actually takes a massive opening to really make a dangerous shockwave.
Eg, if a joint in the tube disconnects and the two halves pull apart, the inlet area is the tube circumference * gap between halves. The two halves would need to separate by the full diameter of the tube (~15 ft) to get full atmospheric pressure going in both sides. A realistic gap of a couple inches to a couple feet is far less scary.
Second, these incidents will be exceptionally rare. Gaps that big are equivalent to a freeway overpass collapsing. It's a total failure scenario, so you see a single digit number of them a year in the US.
Lastly, the speed of sound isn't all that quick on the scale of this thing. It's about 13 miles/min, a fifth of a mile a second.
If you place emergency fill valves (one time use things, dirt cheap, just explosive bolts in the simplest case) you can flood a whole section of the tube with atmosphere in a controlled manner over say 15 seconds, and your shockwave will be largely stopped after 3 miles.
An emergency fill like that would also stop all pods in the region as they hit very high drag, so you don't even need to carry heavy emergency brakes on every vehicle.
2) Because in the case of an explosive recompression there might not be a tube anymore.
I'm not bullish on hyperloop but I see no reason to believe that the engineers can't design a pod capable of not disintegrating in air, or capable of designing a track with a failure mode better than completely falling apart.
https://www.youtube.com/watch?v=DDwe2M-LDZQ
The big problem with his air cannon theory is, pipes are not lossless! Friction and viscous interactions between the entering air and the tube wall will slow down that "shock front" to a highway speed wind in only a couple km. So unless it's so close that the pod can't stop in time (and actually derails at the breach), there should be no loss of life.
As far as thermal expansion, that can be solved with sliding interfaces every few hundred meters. The Hyperloop has switched to mag-lev designs for levitation, so the ultra smooth interior is no longer necessary. There will be some air leakage at the joint of course, but this can easily made up by the pumping stations installed at intervals along the track.
The pressure in the Hyperloop was specifically chosen so that simple mechanical vacuum pumps can be used -- no turbomolecular or cryopumps needed. The Hyperloop runs at 1/1000th of an atmosphere. True "vacuum trains" use vacuums at about 1/1,000,000th of an atmosphere, meaning the pumping is about 1000 times harder (not because the pressure difference is meaningfully different, but because you only get 1/1000th as much air per "stroke" or "cycle").
The Large Hadron Collider uses a harder vacuum still (about 1/1,000,000,000,000 of an atmosphere, and yes that's a trillionth of an atmosphere), which is why LordHumungous's experience mentioned earlier isn't terribly applicable. The LHC is doing something a lot harder than the Hyperloop.
Derail a train = put a rock on the tracks.
Plus there is a planned emergency repressurization of the whole tube that would eliminate even that medium speed shock front. Plus a small 10cm diameter bullet hole would imply in less than 1% of the flow of a completely broken tube (a much harder feat to do), per laws of conservation of energy and matter.
As pods travel with 4km or so of separation, at most one pod will be affected. That is much less people than a derailed train.
For example, there was lots of hang-wringing over Fusion power back in the 1970's, about how if the bureaucrats would just give it more funding then it would happen: https://upload.wikimedia.org/wikipedia/commons/a/ab/U.S._his...
I'm not saying any of this tech is without merit, just that it's common to need buy-in from many organizations to make it happen.
This critique, however, raises quite specific physics-related logistical reasons why Hyperloop is a ludicrously impractical solution for most forms of freight and uneconomical for the rest. Things it doesn't mention, even implicitly, include regulation, government and lawyers. Perhaps you'd get more out of these hyperloop criticisms if you read them?
It's not like investors are blind or dumbstruck just because it's an idea from Musk.
They do their due diligence and if they think the plan has potential, they invest.
I'm sure there were countless technical issues and big challenges around airplanes in the initial stages. And cars. And trains. And, you know, every new technology.
Could Hyperloop (One) fail miserably? Sure. Could it succeed? Also.
Let's just wait and see.
Also, whenever there are invested interests of established competition, they usually drum up the PR machine against new ideas, just as a precaution.
Just look at the fascinating history of fridges vs ice box companies for one of countless examples.
The industry as a whole is far more mature now, and paths to monetization are clearer. Competition is high, so is the competence of most VCs and investors.
I'd also place an engineering project like Hyperloop in a whole different space than the typical SV stuff.
Except, as the article points out, it's not actually faster, cheaper, or efficient than competing technologies. Those seem like really fatal flaws.
> Countries without common law legal systems get around these unnecessary costs much easier.
That same logic also applies to the competing technologies. The same magic wand that lets you build a hyperloop for 1/10th what it would cost in the US also lets you build the tracks for HSR for 1/10th what it would cost in the US. You can't compare the cost of building a hyperloop in China to the cost of building HSR in California and get a meaningful answer.
Nobody is saying that the hyperloop is impossible; they're saying that it's a plan to build something objectively worse than high speed rail at prices that seem broadly comparable.
It's flashy and all to say you're going to break all the rules, but you could just as easily do that with conventional means of transportation.
Especially since the current price of Helium is artificially low, and it's not a renewable resource at current extraction rates, so the price is not going to remain so low in the future.
But it does seem like saying instead of two rails that allow for deviations both horizontally and vertically and the vehicle stays on top, then now we need a really nicely round tube with a different set of requirements that must be maintained over hundreds or thousands of miles.
I guess if hyperloop teams are still in the phase of proving stuff out and they need money then the money they will get will still probably be tiny compared to what it would cost to actually build a real full blown system when you factor in all of the costs of buying land and permits and construction companies.
Caltrain with express trains works very well. sfo and oak have trains that go into the airport. caltrains goal of electrification if it ever happens should make SF to SJ a lot faster. trains in the Bay Area are not as bad as you make them out to be.
personally I think high speed rail should go from Santa Clarita to gilroy or south San Jose. once you pass up the Central Valley you can take bart or Caltrain to your final destination
The article makes some decent sounding criticism on the issue of last mile being the limiting factor. But it all reminds me of what I heard before regarding fast internet connectivity (the issue of the last mile), or why would people need personal computers. The problem with criticizing anything that can impact the future, is that we just don't know how it'll impact it.
I do know that anytime transportation or means of connecting goods or people has been changed, it has had tremendous impact in economy and how the world works.
Do we need to ship cargo at 500 MPH? With today's thinking, maybe no. But I do know by building and experimenting with Hyperloop not only we might just transform the world, in the process will probably make other accidental discoveries as an added bonus.
Fans inside of the tube would pull air in the direction of travel, and it could be circulated or pumped in from / out to the outside at the ends. At the end of the tubes a main fan system would be the primary work horse, creating vacuum forces on the arrival end and pushing forces on the departure end.
In the last mile, the fan system could shut down and use the pressure to help stop the vehicle and even store some of the pressure to help start the system in the opposite direction later (i.e., regenerative breaking).
Among other things it's more efficient to send electricity than to send air.
EDIT:
Wait, if the walls were made to be near frictionless, then the aggregate energy, minus what's lost to hear from turbulence, would be used for motion, right?
Am I thinking if this wrong?
Hyperloop may be an unmitigated disaster. But the effort has clear benefits.
An innovative solution to shifting loads would be immediately useful to air freight, and probably trucking and shipping.
Some solution to the sudden loss of vacuum would be useful in everything from oil pipelines to freeway traffic. Turning the wall of air into a smooth gradient in seconds is perhaps impossible, but even a partial solution would create a whole host of companies to take advantage of the new technique.
New materials developed for the pylons, and techniques for manufacturing those pylons are likely broadly applicable. Bridges are of course an obvious example.
Does every flaw with the hyperloop require science fiction? Or is it just out of reach?
It seems like the Department of Transportation should provide a whole bunch of grad students money to answer the questions, rather than private investors, because those problems sound very big and very risky to me. But if they think they can do it, why not go for it?
A computer analogy I'd give is to think of freight handling like information communication - the big issues are bandwidth (How much can you send/receive in one shipment) latency (How long does it take to arrive) and throughput (How many shipments can you handle at once).
Hyperloop addresses the latency issue but does little to nothing to address the other two problems
From what I see working in a heavy industry which relies on bulk freight (for import and export). Throughput (i.e Congestion) is the hot issue - we have a rail terminal and a deep water berth (which handles capesized ships). The rail corridor is shared and at times pretty heavily congested we use road trains (b-double trucks) to make up for the shortfall.
Getting from Napa Valley to New York, New York in an hour without sitting in a box in the sun would be a big win.
Unsurprisingly, a lot of the theory for transport networks maps extremely well to computer networks.
Transport is essentially a literal packet switched network. You have routers (depots), routes (roads, rails, etc), packets (in many cases, literally packets), MTUs (twenty foot containers, or truckloads).
Queuing theory equally applies to both as well (and a lot of other physical applications, at university we had an exercise applying it to customer support).
Concerning "barf rides": wouldn't Strong and well-timed anesthetics help?
Edit: I worked on the LHC for several years. The challenges of maintaining a closed vacuum pipe that spanned a mere 17 miles were vast and expensive. Musk proposes doing it on an exponentially larger scale without addressing the challenges and pitfalls involved. Until he does so, I cannot take him seriously.
The Alaska Pipeline is certified to operate at 1,180 psi.
It's not a problem, and minor leaks are not a problem, either. A leak that would stop a particle accelerator dead in its tracks will just make a hyperloop operate at slightly lower efficiency. Plus you can always just run the pump (any practical design will doubtless have the pumps running continously to make up for leakage, just as many ships and buildings have continuously-running bilge and sump pumps).
First, part tolerances are not a particularly important issue with engineering of high vacuum systems (sealing is effected by compression of gaskets, usually soft stainless steel gaskets for UHV systems).
Secondly, the difficulties in maintaining a large UHV system is usually related to "outgassing", from multiple surfaces and/or material imperfections, and are rarely due to "a single flaw in one part".
Thirdly, you are using the word "exponentially" wrong, even in the context of your flawed claim which is addressed below.
Finally: "the force on the pipe" is not, in a meaningful sense, proportional to the square of the radius. The forces in the pipe wall are proportional directly to the radius (formula is stress=pressure*radius/thickness), if it was otherwise pipe thickness would grow as the square of diameter and large pressurised pipes would be physically impossible.
Happy to do the math for you when you need it, best to leave it to the experts.
I doubt UHV experience is relevant here though - at 100 torr you can probably get away with simple o-ring seals. And outgassing doesn't matter: even isopropanol has a vapor pressure of only 40 torr.
Edit: The hyperloop design is at ~1 torr, not 100. Still, I'd imagine outgassing is not a huge issue.
The vacuum level required for a particle accelerator (10^-11 torr or something like that) and the one posited for the Hyperloop (0.75 torr) are so far apart that they have virtually nothing in common.
Reminds me of the following quote:
Assholes ARE like opinions - Everyone has one.
You, on the other hand, are overwhelmed by the challenge of maintaining vacuum in a tube that spans a mere 17 miles. At the very least, you should restrain yourself from using language like "...some idea he farted out...".
2) Which Hyperloop is failing? There are at least three groups, and as far as I know, they haven't even got close to testing the system, let alone know if it's a failure or not.
I'm skeptical of the whole concept, but declaring failure at this stage is no less silly than assuming it'll definitively work.
You say 'overwhelmed' but I'll just point out it is built and working, and at almost-perfect vacuum.
one day it might be, and more generally i do hope that we see more progress in the electric car world... but for now tesla only turns a profit as a car company coupled with government incentives. even then, outside of the US (and inside actually) their market share is tiny or zero with very little growth. saying that it doesn't even exist is a very good approximation to reality... if you ignore tech focused news articles and the like at least.
i wouldn't call that a success just yet... as much as we may admire the mission.
Subsidies and protective tariffs are the norm in the auto market.
It would put any car company that didn't get them at a significant disadvantage.
Still quite challenging, but not in the same league, even considering that hyperloop requires way longer tunnels.
I'm no expert either, but that sounds rather hollow..
But Hyperloop is unexplored territory. There isn't billions/trillions of fundamental R&D already done and given away for free by somebody else. I suspect that's going to have an impact.
Now, sure there is a lot of new tech that would be needed. But, less than you might think.
If you're already a maglev, a tube doesn't add much. Japan's maglev has already reached 600 Km/h. The Shanghai/Transrapid maglev routinely runs at 431 Km/h, and has hit 500 in tests. At those speeds, SF-LA is about an hour. But the track cost is very high.
That's not stopping JR Tokai. The Tokyo to Nagoya maglev line has been under construction for two years now. They're taking the most direct route to get the fastest transit time. There are mountain ranges in the way. They're going straight through them. 90% in tunnel. Completion in 2027. Cost comparable to Twitter's peak market cap. Public support for this is so high that JR is being pushed to build the next section, Nagoya to Osaka, sooner.
With enough money...
It all depends on perspective. If decision maker view the maglev as the 21st century version of the railway that let societies prosper in the 19th and 20th, then it might not be expensive at all because the return is so great and the horizon so long.
Drag power is proportional to the cube of velocity, so drag energy losses over a fixed distance are proportional to the square.
In an ideal world you're paying a fixed cost per unit time to pump the tube down then you shove as much stuff as you can through it at transsonic speed, catch it all with regenerative brakes at the other end, and pay an energy per kg payload cost lower than electric road vehicles.
Of course in practice that fixed cost may turn out astronomically high, but that's the idea.
Note the main way in which the JR Maglev will allow adding speed is by building a very straight line for a lot of money, which could benefit conventional rail just as well.
I guess the 18,000 packages per hour that arrive at ANC by jet must also be a matter of "face"?
What does this even mean?
Edit for clarity: The FedEx terminal at Ted Stevens Anchorage International Airport can handle 13,400 packages per hour. The UPS terminal there handles about 5,000 packages per hour. Virtually all of these packages arrive from Asia on jets traveling hundreds of miles per hour (as opposed to the alternative, container ships, which are cheaper, but much slower).
That's because Anchorage is the major airport that's closest to being on a great circle route between North America and Asia. Most of the packages clear customs in Anchorage, and are then fed into the FedEx and UPS systems for further distribution throughout North America.
Clearly there is a very large market for moving cargo at 500 miles per hour. Frankly, I have a hard time believing that an "expert in logistics" would make such a statement.
Alternatively, how much cargo does FedEx or UPS fly along the California coast?
I'm 91% sure that this is less to do with freight specifically and more to do with the amount of weight involved and how it's distributed in each car. Then again, I'm no expert on freight trains.
Is there an app that ensures I never read anything by this guy again? What is his name so I can avoid in the future?
I'm not saying Hyperloop is perfect...its the tone of this jerk.
$141M funding.
EDIT: I found the song!: https://www.youtube.com/watch?v=ZDOI0cq6GZM