5 ms·

If you know the approx speed the train will be going, you can curve harder and camber the track at the right angle to compensate. People will feel slightly heav

If you know the approx speed the train will be going, you can curve harder and camber the track at the right angle to compensate. People will feel slightly heavier, but force will still be toward the floor. Planes do this to the extreme, it's always weird noticing the plane roll 45 degrees and still feeling bum firmly in seat.

seszett 7y ago
HSR trains usually do it as well. In a TGV, you normally don't feel curves at all.
- bobthepanda 7y ago
  The curve radius of new LGV is 7km and cant is 160-180mm. The curve is still absolutely massive and the cant still small.
goodcanadian 7y ago
This is true, but the camber you can use is limited by the fact that you may have to stop the train on the curve without it falling over.
- anticensor 7y ago
  You could implement a strategy of allowing evacuations only at scheduled stops.
  - innocenat 7y ago
    Doesn't work if the train caught fire or something.
  - netsharc 7y ago
    But if the track is distrupted (a tree falls on it, or somehow it's just damaged), the train would have to stop right there and then. Maybe they can make something so the train can grip the ground/tracks so it just doesn't fall off when the forces are no longer acting on it.
    - majewsky 7y ago
      The tracks are not fixed to the ground. If a train grips the tracks in order not to fall over, it will probably still fall over and also rip the tracks out of the railbed as it does so.
      - netsharc 7y ago
        True, as we've learned in this article. I guess it will have to grip to something else. But in the theoretical banking the original comment was talking about (let's say 30 degrees), the track would probably have to be secured to the surface... Well, how heavy is a bullet train, where is its center of gravity, and how much banking does it need if it wants to travel, say, 300 km/h in a (how sharp?) a curve?
        bobthepanda 7y ago
        Keep in mind that banking is only comfortable if you are traveling at the correct speed. There are a whole host of reasons why a train may not travel at maximum speed for a given segment, and the rail line still needs to be reasonably comfortable at all of those.
      - m4rtink 7y ago
        This is not always true, most of Shinkansen track is concrete slab track, which is effectively fixed to the ground. And they actually do have special anti derailment guides build into the track to prevent a train from derailing during an earthquake: https://www.rtri.or.jp/eng/rd/seika/2006/01/safety_E05.html https://www.rtri.or.jp/eng/rd/seika/2006/01/safety_E05.html
- Cthulhu_ 7y ago
  There is / was a train design where the train itself could lean into corners on a flat (legacy) train track. Pretty sure that's not considered anymore because the tilting system adds a lot of weight and complexity. Mag-lev trains seem to reach 'around' the tracks, so that could work. Of course if the levitation stops in a corner (or anywhere, really) on that one it'll cause major damage.
  - jaclaz 7y ago
    >There is / was a train design ... Pendolino: https://en.wikipedia.org/wiki/Pendolino https://en.wikipedia.org/wiki/Pendolino Up to 8-10° , i.e. 1.35 m/s^2 compensation https://it.wikipedia.org/wiki/Pendolino#Caratteristiche_generali https://it.wikipedia.org/wiki/Pendolino#Caratteristiche_gene...
  - m4rtink 7y ago
    Tilting trains are actually in wide use, see: https://en.m.wikipedia.org/wiki/Tilting_train https://en.m.wikipedia.org/wiki/Tilting_train Even the lates shinkansen transets do it to reach higher speed, especially on older parts of the track with sharper turns: https://en.m.wikipedia.org/wiki/N700_Series_Shinkansen https://en.m.wikipedia.org/wiki/N700_Series_Shinkansen
ssmiler 7y ago
Yeah, but in case of emergency stop the train will roll over...
- dsfyu404ed 7y ago
  Not unless the bank angle is so great as to put the center of gravity outside the wheels. Considering how passenger rail cars are build (a deck/chassis to take the push/pull forces with a tin can on top for the cargo) it shouldn't be an issue.
Stratoscope 7y ago
> ...it's always weird noticing the plane roll 45 degrees and still feeling bum firmly in seat. Yes, that is a coordinated turn. It's one of the very first things you learn when you take flying lessons. Airplanes aren't very good at flying sideways. You can make them do it to some degree, and it is an important technique for landing in a crosswind. But they are better at just climbing or descending - from the plane's point of view. So the way you turn is to roll the plane in the direction of the turn and simultaneously start "climbing". Climbing straight "up" from the point of view of the airplane, not up according to the ground. The airplane doesn't know about the ground, it only knows about the air. A coordinated turn is a combination of banking and climbing, such that you always feel like you're being pressed straight down into your seat. And the tighter the turn, the more you are pressed into the seat. When you make a turn in a car on a flat road, you feel a normal 1G straight down and a force pushing you sideways. But if the road were perfectly banked for the speed you're going, you would feel like you were being pressed straight down in your seat. Instead of feeling a sideways force, that would be added to the downward force you feel inside the car - just like an airplane.
- lifeisstillgood 7y ago
  I suspect that making railways perfectly flat for high speed use is hard enough. making them banked at 20+ degrees for several kilometres sounds like a serious engineering challenge
  - vvillena 7y ago
    Banked turns spanning several kilometers are not unusual, even in standard rail systems.
  - jandrese 7y ago
    The other caveat is that banking only works if you're traveling at the correct speed. Too fast and you still feel the turn. Too slow and you feel the bank. For airplanes this isn't a problem because there's never a speed restriction on air. For things that travel along the ground there is no end of reasons why they might have to travel slower than normal.
improbable22 7y ago
Even turns in the vertical direction are a problem, for uncomfortably pushing you into your seat, or lifting the train off the rails. Which results in more bridges & tunnels than would otherwise be needed. Unlike slow trains, there is plenty of power for going up hills, but you can't switch to going down the other side. While ordinary horizontal curves are cambered, IIRC the resulting train-vertical acceleration is still one of the limiting factors.
bobthepanda 7y ago
Planes also require you to strap in and put your tray tables up whenever the seat belt sign is on. There's generally not a meal service happening when the plane is tilting at 45 degrees. One of the competitive advantages that train travel has over plane travel is that it is significantly more comfortable, and you can get up and walk around or have a coffee on your table whenever you'd like. Train travel would be less able to compete with plane travel if the experience was more akin to sitting in a roller coaster.

seszett 7y ago

HSR trains usually do it as well. In a TGV, you normally don't feel curves at all.

bobthepanda 7y ago
The curve radius of new LGV is 7km and cant is 160-180mm. The curve is still absolutely massive and the cant still small.

goodcanadian 7y ago

This is true, but the camber you can use is limited by the fact that you may have to stop the train on the curve without it falling over.

anticensor 7y ago
You could implement a strategy of allowing evacuations only at scheduled stops.
- innocenat 7y ago
  Doesn't work if the train caught fire or something.
- netsharc 7y ago
  But if the track is distrupted (a tree falls on it, or somehow it's just damaged), the train would have to stop right there and then. Maybe they can make something so the train can grip the ground/tracks so it just doesn't fall off when the forces are no longer acting on it.
  - majewsky 7y ago
    The tracks are not fixed to the ground. If a train grips the tracks in order not to fall over, it will probably still fall over and also rip the tracks out of the railbed as it does so.
    - netsharc 7y ago
      True, as we've learned in this article. I guess it will have to grip to something else. But in the theoretical banking the original comment was talking about (let's say 30 degrees), the track would probably have to be secured to the surface... Well, how heavy is a bullet train, where is its center of gravity, and how much banking does it need if it wants to travel, say, 300 km/h in a (how sharp?) a curve?
      - bobthepanda 7y ago
        Keep in mind that banking is only comfortable if you are traveling at the correct speed. There are a whole host of reasons why a train may not travel at maximum speed for a given segment, and the rail line still needs to be reasonably comfortable at all of those.
    - m4rtink 7y ago
      This is not always true, most of Shinkansen track is concrete slab track, which is effectively fixed to the ground. And they actually do have special anti derailment guides build into the track to prevent a train from derailing during an earthquake: https://www.rtri.or.jp/eng/rd/seika/2006/01/safety_E05.html https://www.rtri.or.jp/eng/rd/seika/2006/01/safety_E05.html
Cthulhu_ 7y ago
There is / was a train design where the train itself could lean into corners on a flat (legacy) train track. Pretty sure that's not considered anymore because the tilting system adds a lot of weight and complexity. Mag-lev trains seem to reach 'around' the tracks, so that could work. Of course if the levitation stops in a corner (or anywhere, really) on that one it'll cause major damage.
- jaclaz 7y ago
  >There is / was a train design ... Pendolino: https://en.wikipedia.org/wiki/Pendolino https://en.wikipedia.org/wiki/Pendolino Up to 8-10° , i.e. 1.35 m/s^2 compensation https://it.wikipedia.org/wiki/Pendolino#Caratteristiche_generali https://it.wikipedia.org/wiki/Pendolino#Caratteristiche_gene...
- m4rtink 7y ago
  Tilting trains are actually in wide use, see: https://en.m.wikipedia.org/wiki/Tilting_train https://en.m.wikipedia.org/wiki/Tilting_train Even the lates shinkansen transets do it to reach higher speed, especially on older parts of the track with sharper turns: https://en.m.wikipedia.org/wiki/N700_Series_Shinkansen https://en.m.wikipedia.org/wiki/N700_Series_Shinkansen

ssmiler 7y ago

Yeah, but in case of emergency stop the train will roll over...

dsfyu404ed 7y ago
Not unless the bank angle is so great as to put the center of gravity outside the wheels. Considering how passenger rail cars are build (a deck/chassis to take the push/pull forces with a tin can on top for the cargo) it shouldn't be an issue.

Stratoscope 7y ago

> ...it's always weird noticing the plane roll 45 degrees and still feeling bum firmly in seat. Yes, that is a coordinated turn. It's one of the very first things you learn when you take flying lessons. Airplanes aren't very good at flying sideways. You can make them do it to some degree, and it is an important technique for landing in a crosswind. But they are better at just climbing or descending - from the plane's point of view. So the way you turn is to roll the plane in the direction of the turn and simultaneously start "climbing". Climbing straight "up" from the point of view of the airplane, not up according to the ground. The airplane doesn't know about the ground, it only knows about the air. A coordinated turn is a combination of banking and climbing, such that you always feel like you're being pressed straight down into your seat. And the tighter the turn, the more you are pressed into the seat. When you make a turn in a car on a flat road, you feel a normal 1G straight down and a force pushing you sideways. But if the road were perfectly banked for the speed you're going, you would feel like you were being pressed straight down in your seat. Instead of feeling a sideways force, that would be added to the downward force you feel inside the car - just like an airplane.

lifeisstillgood 7y ago
I suspect that making railways perfectly flat for high speed use is hard enough. making them banked at 20+ degrees for several kilometres sounds like a serious engineering challenge
- vvillena 7y ago
  Banked turns spanning several kilometers are not unusual, even in standard rail systems.
- jandrese 7y ago
  The other caveat is that banking only works if you're traveling at the correct speed. Too fast and you still feel the turn. Too slow and you feel the bank. For airplanes this isn't a problem because there's never a speed restriction on air. For things that travel along the ground there is no end of reasons why they might have to travel slower than normal.

improbable22 7y ago

Even turns in the vertical direction are a problem, for uncomfortably pushing you into your seat, or lifting the train off the rails. Which results in more bridges & tunnels than would otherwise be needed. Unlike slow trains, there is plenty of power for going up hills, but you can't switch to going down the other side. While ordinary horizontal curves are cambered, IIRC the resulting train-vertical acceleration is still one of the limiting factors.

bobthepanda 7y ago

Planes also require you to strap in and put your tray tables up whenever the seat belt sign is on. There's generally not a meal service happening when the plane is tilting at 45 degrees. One of the competitive advantages that train travel has over plane travel is that it is significantly more comfortable, and you can get up and walk around or have a coffee on your table whenever you'd like. Train travel would be less able to compete with plane travel if the experience was more akin to sitting in a roller coaster.