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Ok I have this pet idea for solving the tricky balance between "express" lines and having enough stops: With electric trains it's pretty trivial to give each ca

Ok I have this pet idea for solving the tricky balance between "express" lines and having enough stops: With electric trains it's pretty trivial to give each car it's own motor, so what if every time you approach a stop the front car detaches from the train and shifts to the stop and a car at the station accelerates and attaches to the front of the train (or vice versa), all without the train ever stopping? Maybe it would have to slow a bit to make the attachment/detachment smoother, but you'd still skip the boarding wait and if it was going from like 600-300kph that would still be vastly better than starting and stopping. You would board the train and get on the car that detaches at your intended destination. In the case that they want to run fewer cars than there are stops, either they could alternate which car detaches so that a core car makes it from start to end, or people wanting to make the whole trip would have to change cars sometimes. Is this impossible? Would it be implausibly expensive? Is it "just an engineering challenge" like hydrogen fuel-cell cars (I.E. we'll figure it out just as soon as we have a better alternative)? I have no idea, but it sure sounds cool to me, and it doesn't feel like it's in the realm of fantasy.

prh21 2y ago
I have thought about this as well. There are at least two issues: 1) The number of trains on the track would increase significantly making section control even harder. (In Germany this is one of the limiting factors for the overall capacity) 2) In order to attach/detach the front and back of the trains would have to be straight and vertical. At higher speeds this would lead to aerodynamic problems. You can see this issue when comparing local commuter trains which are vertical and often can be linked this way and high-speed trains which tend to have special aerodynamically shaped noses. The higher the speed the more elongated the nose.
- card_zero 2y ago
  Some precedence in the mail hook. https://en.wikipedia.org/wiki/Catcher_pouch https://en.wikipedia.org/wiki/Catcher_pouch
M95D 2y ago
You want to switch tracks while the trains passes over them? Imagine what would happen if the switch fails!
the_mitsuhiko 2y ago
> so what if every time you approach a stop the front car detaches from the train and shifts to the stop and a car at the station accelerates and attaches to the front of the train (or vice versa), all without the train ever stopping? Has been done historically: https://en.wikipedia.org/wiki/Slip_coach https://en.wikipedia.org/wiki/Slip_coach

prh21 2y ago

I have thought about this as well. There are at least two issues: 1) The number of trains on the track would increase significantly making section control even harder. (In Germany this is one of the limiting factors for the overall capacity) 2) In order to attach/detach the front and back of the trains would have to be straight and vertical. At higher speeds this would lead to aerodynamic problems. You can see this issue when comparing local commuter trains which are vertical and often can be linked this way and high-speed trains which tend to have special aerodynamically shaped noses. The higher the speed the more elongated the nose.

card_zero 2y ago
Some precedence in the mail hook. https://en.wikipedia.org/wiki/Catcher_pouch https://en.wikipedia.org/wiki/Catcher_pouch

M95D 2y ago

You want to switch tracks while the trains passes over them? Imagine what would happen if the switch fails!

the_mitsuhiko 2y ago

> so what if every time you approach a stop the front car detaches from the train and shifts to the stop and a car at the station accelerates and attaches to the front of the train (or vice versa), all without the train ever stopping? Has been done historically: https://en.wikipedia.org/wiki/Slip_coach https://en.wikipedia.org/wiki/Slip_coach