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> Airports can land a plane every minute. A rail line would never dare have two high speed trains that close to each other. Why the difference? If I naively gu

> Airports can land a plane every minute. A rail line would never dare have two high speed trains that close to each other. Why the difference? If I naively guessed, I would think that trains were easier to control and more predictable, so the docking rate should theoretically be higher than for a plane. Is the real limitation not the docking, but the high speed travel up to he docking? Trains all follow the same track, but planes can travel in parallel until 5e final approach?

sandworm101 7y ago
Because if a plane has a problem, those behind it can maneuver around in three dimensions. Trains move in one dimension. If a train has an accident (ie comes to an unexpected stop) the trains behind it must be far enough away that they can also stop. They cannot maneuver around the blockage. Allowing for detection and communication times, at 400+kph that safety margin will be much more than a minute.
- rolleiflex 7y ago
  That’s technically true, but for any distance that is resembling of a train’s stopping distance, planes are fairly one dimensional, too. Passenger planes feel agile from the inside, but from the outside they’re just about a hundred tonnes on a tube of aluminium hurtling forwards at all costs, with just about as much steering capability as that begets.
cpitman 7y ago
The limitation for train capacity is the need to maintain a "block" to ensure that a train has enough time to brake in the case of an emergency, without hitting the train in front of it. For Japan's high speed rail, it takes ~2.5 miles to stop a train. On top of that, many railroads still operate with a static set of blocks, where the track is divided into areas called blocks that do not change over time. Only one train has essentially a lock on a block at a time. So a train has to own the block it is on, but also needs to get access to the next block early enough to avoid an emergency braking event. This reduces the capacity of a line. There's a movement towards "moving block" systems, where railroads use sensors to track train movement and create a moving buffer around the train, which should increase capacity.

sandworm101 7y ago

Because if a plane has a problem, those behind it can maneuver around in three dimensions. Trains move in one dimension. If a train has an accident (ie comes to an unexpected stop) the trains behind it must be far enough away that they can also stop. They cannot maneuver around the blockage. Allowing for detection and communication times, at 400+kph that safety margin will be much more than a minute.

rolleiflex 7y ago
That’s technically true, but for any distance that is resembling of a train’s stopping distance, planes are fairly one dimensional, too. Passenger planes feel agile from the inside, but from the outside they’re just about a hundred tonnes on a tube of aluminium hurtling forwards at all costs, with just about as much steering capability as that begets.

cpitman 7y ago

The limitation for train capacity is the need to maintain a "block" to ensure that a train has enough time to brake in the case of an emergency, without hitting the train in front of it. For Japan's high speed rail, it takes ~2.5 miles to stop a train. On top of that, many railroads still operate with a static set of blocks, where the track is divided into areas called blocks that do not change over time. Only one train has essentially a lock on a block at a time. So a train has to own the block it is on, but also needs to get access to the next block early enough to avoid an emergency braking event. This reduces the capacity of a line. There's a movement towards "moving block" systems, where railroads use sensors to track train movement and create a moving buffer around the train, which should increase capacity.