3 ms·

I presume then they are computer controlled? If so, how does one actually leave early or late?

by neom 5y ago

klodolph 5y ago
There’s a limited amount of computer control, you have people checking to see that the platform is clear and it’s safe to leave. Meanwhile, the computer is controlling a physical system and it’s not like the control will be perfect… everything from weather to mechanical failures will affect it.
myrandomcomment 5y ago
They have a driver.
bdonlan 5y ago
The signal will often go green (or in the case of this line, ATC will show that the train is cleared to proceed) prior to the actual departure time. This is because the trains are not allowed to close their doors until they have a departure signal, so this has to happen well before the actual departure time. Depending on the station configuration and signalling technology the signal clearing may simply occur automatically once the line ahead is clear, so it's up to the train driver to ensure that they don't depart too early.
jrockway 5y ago
Computer control is nice but it's one tiny piece. If wayside infrastructure fails during rush hour, trains are going to be delayed, so they have to assure that won't happen. Station dwell times are another big issue that computers don't have any control over (the train can't leave when someone's backpack is caught in the door). Computer control is more of a safety issue than a reliability enhancer. Computers are pretty good at stopping trains before they crash into another train or rocket off of a curve some idiot took at 80mph, but not so good at driving the train at its safe limits. Ever ride BART? It's been fully automatic since its inception (in normal operation, drivers have an e-stop button and make announcements) and it isn't setting records for on-time performance. I think the fascination with Japan's on-time record is a little overblown. I went to high school in Tokyo and I was late plenty of times due to train problems. Snow? Schedule is fucked for the entire day; trains canceled, trains late. Someone falls in front of a train? You're not going anywhere for an hour. As a rider of the New York subway system during the "meltdown", I can tell you that you can absolutely do worse than Japan. But the MTA was still happy to hand out vouchers explaining why I was late to work.
- cogman10 5y ago
  > Computer control is nice but it's one tiny piece. I don't know if they do this, but I'd imagine if they built in buffers and then controlled the train speed based on arrival/departure times they could get pretty accurate. If a run's maximum average speed (mouthful) is 120 km/h then plan on 100 km/h which gives you +20 buffer to play with in order to make sure the time is right. A computer would allow that +20 to be evenly spread so passengers aren't aware of it. That, of course, has much less to do with computers and more to do with planning and eliminating and accounting for unknowns as much as possible.
- anticensor 5y ago
  > the train can't leave when someone's backpack is caught in the door It can, if the door slam shuts instead of attempting to reopen and close.
bobthepanda 5y ago
Japanese train drivers are trained to the extreme, with periodic auditing by the trainers that involves being timed with a stopwatch as they cover the speedometer. https://youtu.be/xzkU6tmdImY?t=205 https://youtu.be/xzkU6tmdImY?t=205 The high punctuality isn't necessarily without its faults; it creates a high-stress environment to adhere to schedule. 106 people died in a train crash that is hypothesized to have happened because the train was 60 seconds late. https://en.wikipedia.org/wiki/Amagasaki_derailment https://en.wikipedia.org/wiki/Amagasaki_derailment

I presume then they are computer controlled? If so, how does one actually leave early or late?

by neom 5y ago

I presume then they are computer controlled? If so, how does one actually leave early or late?

There’s a limited amount of computer control, you have people checking to see that the platform is clear and it’s safe to leave. Meanwhile, the computer is controlling a physical system and it’s not like the control will be perfect… everything from weather to mechanical failures will affect it.

myrandomcomment 5y ago

They have a driver.

bdonlan 5y ago

The signal will often go green (or in the case of this line, ATC will show that the train is cleared to proceed) prior to the actual departure time. This is because the trains are not allowed to close their doors until they have a departure signal, so this has to happen well before the actual departure time. Depending on the station configuration and signalling technology the signal clearing may simply occur automatically once the line ahead is clear, so it's up to the train driver to ensure that they don't depart too early.

jrockway 5y ago

Computer control is nice but it's one tiny piece. If wayside infrastructure fails during rush hour, trains are going to be delayed, so they have to assure that won't happen. Station dwell times are another big issue that computers don't have any control over (the train can't leave when someone's backpack is caught in the door). Computer control is more of a safety issue than a reliability enhancer. Computers are pretty good at stopping trains before they crash into another train or rocket off of a curve some idiot took at 80mph, but not so good at driving the train at its safe limits. Ever ride BART? It's been fully automatic since its inception (in normal operation, drivers have an e-stop button and make announcements) and it isn't setting records for on-time performance. I think the fascination with Japan's on-time record is a little overblown. I went to high school in Tokyo and I was late plenty of times due to train problems. Snow? Schedule is fucked for the entire day; trains canceled, trains late. Someone falls in front of a train? You're not going anywhere for an hour. As a rider of the New York subway system during the "meltdown", I can tell you that you can absolutely do worse than Japan. But the MTA was still happy to hand out vouchers explaining why I was late to work.

cogman10 5y ago
> Computer control is nice but it's one tiny piece. I don't know if they do this, but I'd imagine if they built in buffers and then controlled the train speed based on arrival/departure times they could get pretty accurate. If a run's maximum average speed (mouthful) is 120 km/h then plan on 100 km/h which gives you +20 buffer to play with in order to make sure the time is right. A computer would allow that +20 to be evenly spread so passengers aren't aware of it. That, of course, has much less to do with computers and more to do with planning and eliminating and accounting for unknowns as much as possible.
anticensor 5y ago
> the train can't leave when someone's backpack is caught in the door It can, if the door slam shuts instead of attempting to reopen and close.

bobthepanda 5y ago

Japanese train drivers are trained to the extreme, with periodic auditing by the trainers that involves being timed with a stopwatch as they cover the speedometer. https://youtu.be/xzkU6tmdImY?t=205 https://youtu.be/xzkU6tmdImY?t=205 The high punctuality isn't necessarily without its faults; it creates a high-stress environment to adhere to schedule. 106 people died in a train crash that is hypothesized to have happened because the train was 60 seconds late. https://en.wikipedia.org/wiki/Amagasaki_derailment https://en.wikipedia.org/wiki/Amagasaki_derailment