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[quote user="ICLand"] [quote user="Bucyrus"] [quote user="ICLand"] Let me expand that a little: mph/energy use index 10         1 50       14 100    197 150    358 200    570 250    832 300   1143 Kind of a "wow," set of numbers, but, the HSR would only have to carry 14 passengers to equal the energy efficiency of 14 people using their individual cars to travel 300 miles. A car and a trainset are a little bit of apples and oranges in this comparison, and so this is very, very rough, but I suppose there is a limited economic argument. [/quote] I don’t understand how you arrived at that conclusion.  Wouldn’t you need to calculate the energy needed to move the train carrying 14 people, and the energy needed to move 14 automobiles with one person in each? [/quote] And I apologize, after I posted it, I thought, well this is not going to be crystal clear.   The car uses 14 units at 50 mph. The HSR uses 1143 units at 300 mph.    But, the car only covers 50 miles in an hour at 50 mph. To cover the same distance as the HVR, the car has to use 14 x 6, or 84 units of energy equivalents (which are not the same for each type of system) to cover the same distance as the HSR example.   So, in that instance, 14 cars with 14 people would use as much energy as one HSR trip carrying 14 people, each covering 300 miles; to the extent this relatively poor example compares a car and the HSR as equivalent users of energy; however the relationship is relatively accurate in terms of efficiency of use of energy; but they aren't directly comparable except in a broad, "it's all I've got right now," sense. The Davis formula is made for trains. Trying to extrapolate it down to a rubber tired equivalent weighing a couple of tons is not going to offer any engineering precision whatsoever. [/quote] Okay, I understand that aspect of your calculation.  The higher speed uses more energy than the lower speed, but the higher speed gets the job done faster, so you have to account for that higher productivity of the higher speed. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p> But, I further question your conclusion in this regard:    Your table compares energy consumed relative to speed of the vehicle.  According to the table, any given vehicle uses 1143 times the energy to travel at 300 mph as it does to travel at 10 mph.  All this does is show how energy use rises with speed for a given vehicle.  However, I do not see how you can compare two different vehicles, which have vastly different weights and come to any conclusion about energy use comparison according to the table you have cited.  <o:p></o:p> Look at it this way: <o:p></o:p> A 300-ton train uses 1143 times the energy to travel 300 mph as it does to travel 10 mph. <o:p></o:p> A 1.5-ton car uses 1143 times the energy to travel 300 mph as it does to travel at 10 mph.   But it does not follow that a 300-ton train uses 1143 times the energy to travel 300 mph as a 1.5-ton car uses to travel 10 mph.
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