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I am intrigued, but not overwhelmed. Many of his reasons why his hyperloop is superior to high speed rail are not specific to the hyperloop. For example, you ca

I am intrigued, but not overwhelmed. Many of his reasons why his hyperloop is superior to high speed rail are not specific to the hyperloop. For example, you can put railway tracks up on pylons, too, with very little impact on the ground. It is common to do this in urban areas, but it is rarely done in rural areas because it is flat out cheaper to put it on the ground. I don't believe that an experimental tube is going to be somehow magically cheaper and easier to route and build than train tracks. Now, I am not trying to defend California's HSR, specifically. I agree with Musk that it appears to be very poorly done. However, the answer, to my mind, is to do it properly rather than propose a wild experiment with hand-wavy arguments as to why it would be politically easier to do. Do you really think the special interests that are making HSR so difficult and expensive would say, "Oh, do whatever you like with your tube."? Now, in an attempt to end on a positive note, I do like his proposal as a possible next step beyond HSR. Rail can go up to 350km/h currently (perhaps more in the future--why wouldn't California design with this goal in mind?), but Musk's hyperloop is proposed up to ~1000km/hr. It is definitely an idea worth exploring, but I think it falls far short as a serious alternative to the current high speed rail plans.

enraged_camel 13y ago
>>However, the answer, to my mind, is to do it properly rather than propose a wild experiment with hand-wavy arguments as to why it would be politically easier to do. Do you really think the special interests that are making HSR so difficult and expensive would say, "Oh, do whatever you like with your tube."? Even when done properly, HSR has most of the limitations stated by Musk. And while it is possible that special interest groups would make the construction of Hyperloop more difficult than it is, I don't think that's an argument against giving it a try.
Anechoic 13y ago
I don't believe that an experimental tube is going to be somehow magically cheaper and easier to route and build than train tracks. Do you really think the special interests that are making HSR so difficult and expensive would say, "Oh, do whatever you like with your tube."? These are extremely important issues that advocates seem to be glossing over. Putting the guideway on pylons doesn't magically eliminate land issues, you will still have to deal with visual impacts, along with any number of anticipated and unanticipated problems. Musk should do what the Germans did with the TR0x series of maglev vehicles, build a 10-20 mile test section someplace and demonstrate that is analysis is sound. (perhaps more in the future--why wouldn't California design with this goal [350 km/h] in mind?) There are a variety of reasons, but one important reason I have to deal with is that the speed of shear waves through soil is only on the order of a couple of hundred miles per hour. When a train exceeds the shear wave speed, ground-borne vibration waves "build up" in a manner similar to the shock wave created in air when a plane exceeds the speed of sound, causing a ground-borne vibration equivalent of a "sonic boom" that can cause problems for wayside structures. I believe the French have started to experience this with some of their higher-speed TGV experiments and we don't have a good way to handle this yet.
- digikata 13y ago
  > When a train exceeds the shear wave speed, ground-borne vibration waves "build up" in a manner similar to the shock wave created in air when a plane exceeds the speed of sound... Putting the railway or tubes on pylons would give you an opportunity to dampen or otherwise transform those vibrations wouldn't they?
  - Anechoic 13y ago
    Putting the railway or tubes on pylons would give you an opportunity to dampen or otherwise transform those vibrations wouldn't they? Maybe, maybe not. Guideway supports (pylons) are typically founded into the bedrock which does reduce vibration somewhat, but the vertical motion of the pylon moving against the soil will still generate shear waves. This is why a demonstration project would be useful.
    - pxtang 13y ago
      I recall reading that the pylons had vertical and horizontal dampers to protect against earthquakes (among other minor natural changes), so wouldn't those dampers be able to cancel out the shear waves?
      - Anechoic 13y ago
        No. Well, I suppose you could design an active vibration system to (almost) completely cancel the vertical vibration motion, but know you're talking about a powered system in each pylon of incredible complexity. Passive resilient systems could help with higher frequency vibration (above say 100 Hz or so, depending on the forces and weights involved), but for lower frequency vibration (especially below 20 Hz), the resilient elements would have to be so compliant that even a gentle breeze would create very high vibrations in the guideway itself, which would be incompatible with the speeds of the cars inside. You could make the pylons so massive that the forces from the vehicles couldn't move it, but again you're talking about higher construction and material costs, as well as visual impacts.
jeffasinger 13y ago
The tube is not nearly as wide or heavy as a traditional train, so I don't know that it's fair to say that you can just as easily put a train up on pylons as you could this tube. It's interesting to think about, but also there are probably much higher costs associated with a completely untested system like this than estimated. I wouldn't be surprised if this system, if it actually worked at all, ended up being more expensive than a HSR proposal through California that actually made sense.
- jessriedel 13y ago
  But why make it a traditional train? Just build a lightweight train if it gets you all of the hyperloop's cost advantages without the additional costs and complexity of a tube?
  - jim-greer 13y ago
    On trains the cars have to be connected to each other. The structure has to bear the load of all of them at once. Not the case with hyperloop.
    - jessriedel 13y ago
      It's totally implausible that that's the primary factor.
      - LockeWatts 13y ago
        Why? You've given no explanation.
        jessriedel 13y ago
        Nor has jim-greer.
    - lmm 13y ago
      The reason we have to run long, heavy trains is it's unsafe to run two passenger capsules at 300kph a minute apart. I find it hard to believe regulations will permit that even when they're in a tube.
cma 13y ago
Can you elevate rail as easily? We're talking a lot more weight being carried by the pillars in that case. Plus you don't get the same natural banking off the walls he talks about, which is relevant at these speeds. While rail could bank, you better be going at the right speed when doing so, too slow and you just fall laterally off the tracks.
- goodcanadian 13y ago
  Can you elevate rail as easily? The short answer is, "yes." I've ridden on it. The slightly longer answer (as another commenter has pointed out) is that it depends on the weight of the train versus the weight of the hyperloop. I see no fundamental reason to assume that the hyperloop is lighter than the train. It could be so, but then, we could make smaller and lighter trains, too (light rail). Plus you don't get the same natural banking off the walls he talks about, which is relevant at these speeds. While rail could bank, you better be going at the right speed when doing so, too slow and you just fall laterally off the tracks. This is a problem even when you are at grade. The solution is known: tilt-trains. The track is banked such that the train will not fall over if it has to stop on the curve. The passenger cabin then tilts with respect to the wheels so that it always feels like the floor is "down" regardless of the speed that the train goes around the curve. The radius of curve sets the maximum speed the train can travel around it.
  - Turing_Machine 13y ago
    "I see no fundamental reason to assume that the hyperloop is lighter than the train." Did you actually read the PDF? It doesn't carry its motor with it. That's a pretty big reason. Nor does it need the heavy-duty (and heavy!) trucks of a standard rail car.
    - deleted 13y ago
      [deleted]
    - jim-greer 13y ago
      A bigger factor is that the efficiency of a train depends on having all the cars connected to each other. With the hyperloop, the pods are spaced out, so there's no need for the structure to bear the load of a bunch of them at once.
fizx 13y ago
Steel tube is inherently far more structurally stable than rail. This should make elevation easier/cheaper. Edit: apparently, the weight of the train/car/etc matters more.
sjs382 13y ago
> For example, you can put railway tracks up on pylons, too, with very little impact on the ground. Out of curiosity (I'm not at all familiar with HSR)—does the Hyperloop plan increase the distance between columns or the cost to build the columns (due to materials or any other factors)?
DonPedro 13y ago
The basic issue the hyperloop overcomes is the energy waste in train transportation, especially at high speeds. This is primarily about aerodynamics, and secondarily about carrying with you the propulsion system. Third, it overcomes the "chunkiness" of the rail system, where passangers needs to be assembled and grouped into train-sized lots for transportation, rather than being able to depart continuously. You get superior energy economics, speed and convenience. I cannot see how that would be disappointing.

enraged_camel 13y ago

>>However, the answer, to my mind, is to do it properly rather than propose a wild experiment with hand-wavy arguments as to why it would be politically easier to do. Do you really think the special interests that are making HSR so difficult and expensive would say, "Oh, do whatever you like with your tube."? Even when done properly, HSR has most of the limitations stated by Musk. And while it is possible that special interest groups would make the construction of Hyperloop more difficult than it is, I don't think that's an argument against giving it a try.

Anechoic 13y ago

I don't believe that an experimental tube is going to be somehow magically cheaper and easier to route and build than train tracks. Do you really think the special interests that are making HSR so difficult and expensive would say, "Oh, do whatever you like with your tube."? These are extremely important issues that advocates seem to be glossing over. Putting the guideway on pylons doesn't magically eliminate land issues, you will still have to deal with visual impacts, along with any number of anticipated and unanticipated problems. Musk should do what the Germans did with the TR0x series of maglev vehicles, build a 10-20 mile test section someplace and demonstrate that is analysis is sound. (perhaps more in the future--why wouldn't California design with this goal [350 km/h] in mind?) There are a variety of reasons, but one important reason I have to deal with is that the speed of shear waves through soil is only on the order of a couple of hundred miles per hour. When a train exceeds the shear wave speed, ground-borne vibration waves "build up" in a manner similar to the shock wave created in air when a plane exceeds the speed of sound, causing a ground-borne vibration equivalent of a "sonic boom" that can cause problems for wayside structures. I believe the French have started to experience this with some of their higher-speed TGV experiments and we don't have a good way to handle this yet.

digikata 13y ago
> When a train exceeds the shear wave speed, ground-borne vibration waves "build up" in a manner similar to the shock wave created in air when a plane exceeds the speed of sound... Putting the railway or tubes on pylons would give you an opportunity to dampen or otherwise transform those vibrations wouldn't they?
- Anechoic 13y ago
  Putting the railway or tubes on pylons would give you an opportunity to dampen or otherwise transform those vibrations wouldn't they? Maybe, maybe not. Guideway supports (pylons) are typically founded into the bedrock which does reduce vibration somewhat, but the vertical motion of the pylon moving against the soil will still generate shear waves. This is why a demonstration project would be useful.
  - pxtang 13y ago
    I recall reading that the pylons had vertical and horizontal dampers to protect against earthquakes (among other minor natural changes), so wouldn't those dampers be able to cancel out the shear waves?
    - Anechoic 13y ago
      No. Well, I suppose you could design an active vibration system to (almost) completely cancel the vertical vibration motion, but know you're talking about a powered system in each pylon of incredible complexity. Passive resilient systems could help with higher frequency vibration (above say 100 Hz or so, depending on the forces and weights involved), but for lower frequency vibration (especially below 20 Hz), the resilient elements would have to be so compliant that even a gentle breeze would create very high vibrations in the guideway itself, which would be incompatible with the speeds of the cars inside. You could make the pylons so massive that the forces from the vehicles couldn't move it, but again you're talking about higher construction and material costs, as well as visual impacts.

jeffasinger 13y ago

The tube is not nearly as wide or heavy as a traditional train, so I don't know that it's fair to say that you can just as easily put a train up on pylons as you could this tube. It's interesting to think about, but also there are probably much higher costs associated with a completely untested system like this than estimated. I wouldn't be surprised if this system, if it actually worked at all, ended up being more expensive than a HSR proposal through California that actually made sense.

jessriedel 13y ago
But why make it a traditional train? Just build a lightweight train if it gets you all of the hyperloop's cost advantages without the additional costs and complexity of a tube?
- jim-greer 13y ago
  On trains the cars have to be connected to each other. The structure has to bear the load of all of them at once. Not the case with hyperloop.
  - jessriedel 13y ago
    It's totally implausible that that's the primary factor.
    - LockeWatts 13y ago
      Why? You've given no explanation.
      - jessriedel 13y ago
        Nor has jim-greer.
  - lmm 13y ago
    The reason we have to run long, heavy trains is it's unsafe to run two passenger capsules at 300kph a minute apart. I find it hard to believe regulations will permit that even when they're in a tube.

cma 13y ago

Can you elevate rail as easily? We're talking a lot more weight being carried by the pillars in that case. Plus you don't get the same natural banking off the walls he talks about, which is relevant at these speeds. While rail could bank, you better be going at the right speed when doing so, too slow and you just fall laterally off the tracks.

goodcanadian 13y ago
Can you elevate rail as easily? The short answer is, "yes." I've ridden on it. The slightly longer answer (as another commenter has pointed out) is that it depends on the weight of the train versus the weight of the hyperloop. I see no fundamental reason to assume that the hyperloop is lighter than the train. It could be so, but then, we could make smaller and lighter trains, too (light rail). Plus you don't get the same natural banking off the walls he talks about, which is relevant at these speeds. While rail could bank, you better be going at the right speed when doing so, too slow and you just fall laterally off the tracks. This is a problem even when you are at grade. The solution is known: tilt-trains. The track is banked such that the train will not fall over if it has to stop on the curve. The passenger cabin then tilts with respect to the wheels so that it always feels like the floor is "down" regardless of the speed that the train goes around the curve. The radius of curve sets the maximum speed the train can travel around it.
- Turing_Machine 13y ago
  "I see no fundamental reason to assume that the hyperloop is lighter than the train." Did you actually read the PDF? It doesn't carry its motor with it. That's a pretty big reason. Nor does it need the heavy-duty (and heavy!) trucks of a standard rail car.
  - deleted 13y ago
    [deleted]
  - jim-greer 13y ago
    A bigger factor is that the efficiency of a train depends on having all the cars connected to each other. With the hyperloop, the pods are spaced out, so there's no need for the structure to bear the load of a bunch of them at once.

fizx 13y ago

Steel tube is inherently far more structurally stable than rail. This should make elevation easier/cheaper. Edit: apparently, the weight of the train/car/etc matters more.

sjs382 13y ago

> For example, you can put railway tracks up on pylons, too, with very little impact on the ground. Out of curiosity (I'm not at all familiar with HSR)—does the Hyperloop plan increase the distance between columns or the cost to build the columns (due to materials or any other factors)?

DonPedro 13y ago

The basic issue the hyperloop overcomes is the energy waste in train transportation, especially at high speeds. This is primarily about aerodynamics, and secondarily about carrying with you the propulsion system. Third, it overcomes the "chunkiness" of the rail system, where passangers needs to be assembled and grouped into train-sized lots for transportation, rather than being able to depart continuously. You get superior energy economics, speed and convenience. I cannot see how that would be disappointing.