Innovation in rail travel: The train that never stops at a station
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http://blog.modernmechanix.com/2008/12/18/train-picks-up-and...
Well. It's pretty much unworkable. Train is not a single rigid body, it's composed from bogies and car bodies, and they are only quite loosely attached. They absolutely have to be. So you can't expect it to just sit as a rock on the tracks, even in pretty low speeds. And with speed low enough, you are maybe better to simply stop. Modern electric bullet train unit with high powered axles ratio can accelerate really, really fast.
Anyway, you could spend money much better on allowing higher speeds on the whole track, or improving adjacent tracks so to allow higher speeds even for feeders and conventional trains, which could allow you to make fewer stops.
Yes, but accelerating the entire train is going to cost way more energy than accelerating the transfer car. Also, the transfer car can simply use wheels and brakes to gain kinetic energy from the train, so it can be incredibly light. Even if a longer track and motor are necessary for high speed bullet trains, there would still be a big energy savings.
Also, no matter how quickly you can accelerate to make a stop quickly, the same train will be able to save considerable trip time with the transfer car system. Saving a half hour or hour off of trip time from a route is certainly worthwhile, especially if it means that the train can run the same route at a lower top speed. The energy savings from that could be enormous over the long term.
Seems like it's everywhere these days. Even in urban metro lines where you've got like 1km between stations. HK subway trains have been doing this since the 90s. Wikipedia sez Delhi Metro has it too.
(And even if you don't give the energy back to the network and just burn it in the resistors in locomotive, it gives you more effective braking. Locomotives from 1960's already had that.)
You could save some energy by using only recuperating electrodynamic brake to zero to stop the train and store it in some supercapacitators (not on the train, of course) if there isn't any other train to use it. Because you have many powered axles, you could brake quite effectively and fast enough. Well, possibly still not fast enough to use just EDB.
Raising top speed is of course going to cause much higher aerodynamic drag, so if the energy use is primary concern, it's not exactly the right thing to do. I rather meant eliminating any drops in the average traveling speed except the stations.
But I can't really argue against energy savings, because most likely, there would be energy savings :-) If you could built such a system safe enough (I don't believe that) and with less than absolutely insane costs (I don't believe that either :-)).
Pretty obvious I suppose, but interesting that it was actually used in routine service for a few decades.
For trains it could be nice to use small wagons that could change from a train to another, not because of energy saving, but to achieve more speed, avoiding the time needed to change lines. I agree with a previous commenter that trusting passengers to behave correctly is looking for problems.
* What if the door on the pick-up car gets blocked? Sometimes straggling passengers hold the door open for their friends. It would need to get out of the way to prevent a collision with the drop-off car.
* What if there is a malfunction in the pick-up car so that it is not able to accelerate fast enough to catch up with the train?
* From an engineering point of view this seems fragile -- there are a lot of parts that need to perfectly synchronize with each other. A single error will quickly cascade through the system and result in serious loss of life.
First, it might save lots of energy, but it is also a lot more complicated than just having brakes, which it is going to have anyway.
And how much energy would it really save? It still has to accelerate that detachable portion which could be a substantial fraction of the whole, and furthermore the train would probably need to be substantially heavier to support the extra mechanism, which would be a loss . . .
Still, it is a creative leap, which makes one think about how to be similarly inventive. You have to get some wild ideas before figuring out the details.
At least one train maker still struggles getting this bit right. http://en.wikipedia.org/wiki/Siemens_%28train%29#Braking_iss...
I'd be very worried about safety with something this complex unless it could be proven to always fail in a safe way.
Approaching the station, there's an announcement on the train "Everybody getting off at the next station please move to the last carriage". Then the last carriage simply detaches from the train and coasts into the station to unload at the platform.
Meanwhile, another carriage has been loaded with the passengers who were due to get on at the station. After the train passes the carriage is shunted by a small locomotive to catch up with the train and it attaches to the end.
No need for crazy long parallel tracks and dangerous transfers between high-speed trains. Difficulty: most high-speed trains have locomotives at both ends afaik, but that's a minor issue.
But, if you think that those transfers are dangerous, I don't know what to say about coupling in high speeds. Insane, maybe :-) Coupling even in station when only the locomotive is moving is favorite source of accidents. Basically you'd have to reach almost same speed as the train you are coupling with in the exactly same moment when you are going to touch it, with only very small difference that buffers can absorb. Hard enough if that speed is zero.
It's quite hard to control exact speed of a train (at such high speed), even without any atmospheric effects and with ideal adhesion conditions that never change. I can imagine it in like 50 kph, when the worst thing to expect is a derailment, some deformation zones blasted, and few non-fatal wounds. But every problem rises at least exponentially with the speed.
But if that's the case then it still seems like the original problem of running two trains right alongside each other, on different tracks, for several minutes while people cross from one to another, and with the consequence of any error being passengers getting sliced in half, would be even harder.
Maybe the coupling mechanism could be something long that extends from the back of the train. The cars can connect can over a wide range of distance, kind of like a runway. The connection is made with a friction clutch that can be applied gradually and eased off if something goes wrong. The coupling also has a drive to pull the cars together after they are securely linked.
They could always slow down to make the link too.
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ICE train in Germany got derailed by few sheep two years ago…
It would eliminate the hassles of car rental (especially if the rail stations aren't near airports), obviate the need for checked luggage, and mitigate the increased travel time compared to flying.
Keep in mind that on the whole, Chinese people are much more likely to give up personal property/liberty for the benefit of the state. It's a massive generalization of course, but the difference between Chinese and American mindsets is really significant.
Also, the initial jolt on impact of the pick-up car is going to be very unpleasant, and perhaps even dangerous.