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You can pull a 10 tonne yacht with one hand on a rope. Try pulling a 10 tonne truck... Also according to the US Transportation Energy Book, waterbourne transpo

• robomartin 14y ago
  On your first point, I refer you to Google and Wikipedia for excellent articles on basic physics. In particular look to understand the relationship of power as it relates to speed. On the second point. Our cargo rail system is crap. Nowhere in my write-up am I proposing that we unload 100,000 cargo ships per year and load these containers onto diesel trucks or the current train system. That would be incredibly dumb, inefficient, more harmful to the environment and, well, actually impossible. No, the idea is that a new highly-efficient, all-electric, highly-automated and cargo-only transportation system be built with the express purpose of moving container-based cargo from coast to coast (and port to port) at the highest possible speed and lowest possible power consumption. The idea further suggests that the required energy can come from nuclear, wind and solar power. The complete elimination of the burning of the most harmful form of fossil fuel from the transportation system is one of the stated goals of the idea. Furthermore, the idea is also to look 50, 100 or even 200 years into the future. Pollution aside, fossil fuel cost is absolutely, positively guaranteed to increase over the next 200 years. The current system of burning millions of tons of bunker-c fuel per year to bring widgets to Walmart isn't a viable and scalable long-term solution. Not to mention the fact that it is royally fucking up the environment at many levels. I am not a crazy environmentalist by any measure, but this is stupid.
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  • jasonwatkinspdx 14y ago
    "On the second point. Our cargo rail system is crap. Nowhere in my write-up am I proposing that we unload 100,000 cargo ships per year and load these containers onto diesel trucks or the current train system. That would be incredibly dumb, inefficient, more harmful to the environment and, well, actually impossible." The US freight rail system is the best in the world.[1] We move 10x more than Europe most years on a tons times distance basis. The running gear may look antiquated, but the fundamental numbers are staggering. "No, the idea is that a new highly-efficient, all-electric, highly-automated and cargo-only transportation system be built with the express purpose of moving container-based cargo from coast to coast (and port to port) at the highest possible speed and lowest possible power consumption." There is very little demand for raising the speed of freight rail in the US. Speed generally compounds inefficiencies. Freight handling is by and large already automated and container based in the US rail network. Existing electric designs preclude the use of double stacked container flat cars, one of the keys of US freight efficiency. Perhaps you have an innovation here? Building an entirely new high speed electric rail network for freight is an absurd idea. I don't think you've even begun to model the economic realities, particularly the capex of building a new rail network radius'd and graded for high speed, with all above grade crossings. [1]: http://www.economist.com/node/16636101 http://www.economist.com/node/16636101
    • robomartin 14y ago
      I read that article with interest. Of course our rail system is not crap when compared to others. That's not what I meant. What I meant is that it could be much, much better. The article you point out hints at some of the issues: The inter-mingling of passenger and cargo trains ends-up seriously affecting the potential performance of cargo trains. With regards to it being an absurd idea. Well, of course it is! And so is the case for nearly every idea that sparked a revolution in technology and thinking. The earth NOT at the center of the universe? Absurd! The earth not flat? Absurd? Everyone needs a computer on their desk? Absurd! Not that I am comparing this to any of those shifts in technology. What I am trying to point out is that being open minded enough to even consider the seemingly absurd is an important part of discovering new ideas and developing new technologies. I always consider the absurd. I have hundreds of ideas catalog that are probably absurd. The alternative is to discount everything as ridiculous without even giving it an honest look. I just don't do that. For example: Could this high speed train take the form of an underground tunnel connecting both coasts? This is absolutely ridiculous and probably even insane to consider. However, I take the approach of at least doing the research to try to get a sense of proportion in terms of cost and technical feasibility. For example, would there be an important mining element to the project that could offset the costs? I don't know and I am not trying to argue for a 3,000 mile tunnel. All I am saying is that I believe that it is very important to give seemingly ridiculous ideas a chance to be explored and, if need be, discarded based on data and not knee-jerk reaction.
• robomartin 14y ago
  > You can pull a 10 tonne yacht with one hand on a rope. Try pulling a 10 tonne truck... This probably deserves a little more attention. Having done a lot of sailing as well as ocean-fishing on different size vessels I know exactly what you are talking about. What you might be confusing is that at zero speed there's a huge difference between something floating on water and a truck resting on the ground. In the case of a large boat floating on water, so long as you are not after making it move quickly you are almost just fighting inertia. So, yes, a fifteen year old kid pulling on a rope could make a large boat move. When it comes to a truck sitting on the ground you have to contend with rolling friction as well as the static friction (because nothing is moving) and the viscous drag of all the mechanical elements, oil and grease in the drivetrain. It could take hundreds of pounds of force to get it to budge. Once your break through static friction then you have a much reduced dynamic friction and viscous drag (oil and grease in the drivetrain) --again, so long as speed is very, very low-- as well as the rolling friction of the tires. If, on the other hand, that truck was resting on a frozen lake bed and if the tires are not frozen-glued into the ice, and, if the ice is not deformed under the tires, the same fifteen year old kid could move it just as well as he moved the boat. In fact, it might even be easier because there isn't a significant v^3 component to the power required to make it move. Once you start to add speed to the problem it is easy to see that moving the same object through water will require at least 830 times more water. At speed the power required to counter drag comes into play. Power = 1/2 * fluid density * velocity ^3 * coefficient of drag * area Here's an easy experiment: Take a tennis racket and duct-tape the strung area in order to make it a solid paddle. No air or water should get through. Now swing it in air as fast as you can. Now go into a swimming pool and try to swing it just as hard under water. Unless you are super-human you will not be able to. In fact, you won't be able to even get close to the speed in air. Again, simply stated, you need over 800 times more power to achieve the same speed in water with the same object. If it takes one horsepower to move something in air at a given speed you'll need over 800 horsepower to achieve the same speed in water. It's the difference between a model airplane engine and a Formula 1 race car engine. There's a good article in Wikepedia on drag: http://en.wikipedia.org/wiki/Drag_(physics) http://en.wikipedia.org/wiki/Drag_(physics) Get down to the "Power" heading. That's the formula you want to look at. To get back to your yacht vs. truck example. What you would really have to experience is pulling each of them at 20 or 30 miles per hour with a rope (chain?). Of course, it would take super-human strength and endurance to be able to do that.