h a l f b a k e r yA dish best served not.
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Railway passenger cars are constructed to be extremely rigid. This ensures that if a train that's being pushed at 65mph hits a rigid obstruction the cars will jackknife rather than telescoping and crushing everyone inside. Unfortunately, jackknifing--though less injurious than telescoping--is still
severely injurious to many passengers.
I would propose that the leading car of a pusher-train be constructed so that, other than the control cab (which should be rigid) the entire car could crush longitudinally without derailment. Such compression would preferably use a fluid energy-absorbing medium so as to provide speed-dependent resistance. If desired, this medium could be a fire-suppressant chemical so that if a train was involved in a collision severe enough to crush the energy-absorbtion car, liberal amounts of fire-suppressant would get spread around.
To be sure, a train travelling 65mph isn't going to be able to stop in the length of a single railway car. Nonetheless, any energy absorbed along that length would be energy that didn't have to be absorbed by the rest of the train and its passengers. Because the compression car would be beyond the last point of passenger occupancy, it would not matter if it extended beyond railway platforms. The only difficulty it might pose would be if the extra length would foul switches behind platforms or sidings.
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Annotation:
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Like a giant version of the impact attenuators often attached to the back end of highway construction equipment. |
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//Like a giant version of the impact attenuators often attached to the back end of highway construction equipment.// |
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Exactly. Though in this case, it would be attached to a moving vehicle rather than one that's supposed to be stationary. |
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I've been wondering just how expensive it would be to sense obstacles on the track and either throw a switch or signal the train in some other way. |
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Seems that the same kind of technology as being considered for automated borders could be used, but you would need all new tracks... |
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No, wait, I got it, idea to follow |
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Okay, maybe this idea is a bit on the practical side for halfbakery, but I thought my Sales Tax Shaver should earn me the right to be a little serious. |
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//Railway passenger cars are built to be extremely rigid//
Not in the UK. As built, the front of trains is designed to crush, as are the vestibule areas between cars. Another major consideration is overriding protection - stopping one car from coming straight through another. This is why the South-East is finally replacing its slam-door trains - they have a solid chassis and lightweight cabin. In a crash, one chassis rides over the one in front with total disregard for passengers in its way. |
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//suppose the railcars could rotate about their center, bringing the trucks closer together// So, not suitable for subway trains then? |
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a) An unfilled car would increase fuel consumption considerably. Trains are already an extremely safe mode of transport. There is no point in making it marginally safer at a high cost. |
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b) Modern trains travel at 200mph. Any head-on collision at that kind of speed will be fatal, no matter how much damping you use. |
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The car could be filled with fire retardant, which on compressing the car would be forced up through holes in the ceiling into great arcing jets over the rest of the train. |
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If these cars were cheap (ie made of milk jugs and newspaper) they might be used routinely to brake the car. This would save on brakes. |
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