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Comment by derdi | Hacker News Reader

Bunching also happens on things like subway lines that have no other traffic. Many passengers are irrational about forcing their way onto already overcrowded trains.

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>Many passengers are irrational about forcing their way onto already overcrowded trains.

the train that leaves first gets there first

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although, entering a station once with a friend, we ran for an arriving subway train with a friend. they got on but I did not. however, I was familiar with the station we were in, and the destination station and I realized....

so I ran down the platform, continuing in the same direction, and before I reached the other end of the platform, as I expected, the follow-on train arrived. I boarded it, and now I was ahead of my friend schedulewise: blew their mind when I was waiting for them to exit at the destination station.

Tell me you don't take public transit without telling me you don't take public transit

I don't understand how this is possible. Trains are single track in most subways and metros, and definitely do not stop before an already waiting train.

I think the implication is that the time between two trains was little more than the time it took to walk along the whole platform, which the friend still had to do after getting off, plus someone familiar with the stations not needing time to orient themselves and find the intended exit.

they climbed on the last car of the first train

i ran down the platform and, without any other waiting, climbed on the first car of the next train

they got off the last car of the first train and started to walk in the same direction as the train. while they were walking, the first car of the next train, me, rolled well past them before stopping.

> the train that leaves first gets there first

I understand this is what motivates people, and I also understand that, when asked, they would claim that this is in their rational self-interest. As I also wrote elsewhere, I tend to disagree or at least question this assumption in general. Are you really in that much of a hurry? If you have a very hard deadline, wouldn't it have been in your rational self-interest to leave home five minutes earlier? etc.

> the train that leaves first gets there first

Yeah, but in this bunching scenario I prefer taking a train with lots of space than arriving maybe two minutes earlier packed like a sardine. Having screens which also show when the following trains will arrive helps a lot of course...

Getting on the train that's physically in front of you, no matter how crowded, is the rational decision basically everywhere outside Japan, where you can have metaphysical certitude that the next train will show up as scheduled.

It's not, when you know through announcements that the next train is right behind it and will be much less crowded.

It's not as irrational as all that.

Subway system here has an amazing propensity to send random trains on express tracks, especially during peak traffic. I understand that this is done to alleviate congestion, but the net effect is that when you see a train going somewhere you want, you _seize the opportunity_.

It's a coordination problem - taken in isolation, it's not irrational. If only you refrain from doing it, and 37 other people do, you will still have to wait for the next train, and the train in front of you will be almost as late anyways.

The wait for the next train is one factor, the overcrowding is another one. I'm usually not in such a hurry that a minute's wait would make a difference. But the next train is very likely to be much less crowded and much more comfortable to ride on. From my point of view the decision is clear, in isolation, just from my own selfish point of view. And I think many others are making a choice that makes them unhappy. (Train systems differ, the one where I live has sufficient capacity that you rarely get two overcrowded ones back to back. I know there are places where this does not apply.)

> a minute's wait

Is your subway system running trains every 1-2 minutes (30-60 trains per hour)? Mine has trains at 5-8 minute spacing at peak times and 8-12 minutes off-peak.

No, it's running at 3-5 minutes at peak times. But bunching significantly shortens the interval between the delayed, overcrowded train and the empty one right behind it.

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