3 ms·

When I was in Japan it was strange to see how slow some trains are. You will see that sometimes they stay more time in a station and will accelerate way faster

by kartan 8y ago

When I was in Japan it was strange to see how slow some trains are. You will see that sometimes they stay more time in a station and will accelerate way faster than usual. But when one train arrives it is common that there is another one arriving at the same time. People exchange lines from one train into another in a few seconds and then both of them depart. My feeling is that the optimization is not for the speed of the trains. Japanese trains do not go as fast as they can. But all the train system is optimized to reduce waiting time. Each individual train is slightly slower. But the mean time that Japanese travellers spend is reduced. I would love to see some study about this, as it was just my travel experience. It would be cool to compare that on how ants behave. It will not be the first time that ants have resolved an optimization problem way before even humans existed.

analog31 8y ago
I noticed something similar in Switzerland. First time we went there, it was before cell phones, and we went from A to B by going to the station and telling them where we wanted to go. We were given tickets and a little itinerary. At one station, our "layover" was 1 minute. I protested: "We will never catch our next train." The agent looked at us and said: "You will catch your train." Sure enough, we did. The other thing I noticed was that when one of our trains was delayed a bit, it seemed like they slowed down the entire system so that nobody would miss a connection, and then made it back up on the trip to the next station. We never missed a connection, and the only times when we had to hustle, was because we were nervous Americans accustomed to US air travel. Even the buses were synchronized with the trains.
- panarky 8y ago
  In Eliyahu M. Goldratt's "Theory of Constraints", you can't increase the throughput of a factory by making each step in the manufacturing process faster [1,2]. That only results in building up inventory which actually decreases the efficiency of the entire process. Instead, identify and fix the biggest bottleneck. Even if you do that inefficiently, with more labor, or with a sub-optimal machine, fixing the biggest bottleneck increases total throughput. Once that's done, then focus on the biggest bottleneck of the newly revised process. The counterintuitive result is that by focusing only on constraints, the process steps that are unconstrained will be idle much of the time. Inexperienced factory managers see people standing around doing nothing and think this is inefficiency to be eliminated. Experienced managers realize that idleness is essential at unconstrained stations, and trying to eliminate it will actually decrease total output. [1] https://en.wikipedia.org/wiki/Theory_of_constraints https://en.wikipedia.org/wiki/Theory_of_constraints [2] https://en.wikipedia.org/wiki/The_Goal_(novel) https://en.wikipedia.org/wiki/The_Goal_(novel)
omginternets 8y ago
So basically: they optimize for throughput, not latency.
- Consultant32452 8y ago
  This reminds me of the story where a Houston airport kept getting complaints from airline passengers that it took too long for their luggage to arrive. So they moved baggage claim farther away. This made travelers walk farther to get to their bags, but have a shorter "wait" time. Complaints dropped to zero. I wonder if there is a cultural difference there, where throughput is understood to be better than latency or something. https://www.nytimes.com/2012/08/19/opinion/sunday/why-waiting-in-line-is-torture.html https://www.nytimes.com/2012/08/19/opinion/sunday/why-waitin...
joewee 8y ago
This explains why Japanese train conductors make a big deal out of delays of a few seconds. It’s very common to hear announcements like “sorry we were delayed by 20 seconds because someone was holding the door.” Because that delays the entire line and all connecting trains by 20 seconds. And I’m sure these delays are tracked to measure performance of the conductors.

by kartan 8y ago

analog31 8y ago

I noticed something similar in Switzerland. First time we went there, it was before cell phones, and we went from A to B by going to the station and telling them where we wanted to go. We were given tickets and a little itinerary. At one station, our "layover" was 1 minute. I protested: "We will never catch our next train." The agent looked at us and said: "You will catch your train." Sure enough, we did. The other thing I noticed was that when one of our trains was delayed a bit, it seemed like they slowed down the entire system so that nobody would miss a connection, and then made it back up on the trip to the next station. We never missed a connection, and the only times when we had to hustle, was because we were nervous Americans accustomed to US air travel. Even the buses were synchronized with the trains.

panarky 8y ago
In Eliyahu M. Goldratt's "Theory of Constraints", you can't increase the throughput of a factory by making each step in the manufacturing process faster [1,2]. That only results in building up inventory which actually decreases the efficiency of the entire process. Instead, identify and fix the biggest bottleneck. Even if you do that inefficiently, with more labor, or with a sub-optimal machine, fixing the biggest bottleneck increases total throughput. Once that's done, then focus on the biggest bottleneck of the newly revised process. The counterintuitive result is that by focusing only on constraints, the process steps that are unconstrained will be idle much of the time. Inexperienced factory managers see people standing around doing nothing and think this is inefficiency to be eliminated. Experienced managers realize that idleness is essential at unconstrained stations, and trying to eliminate it will actually decrease total output. [1] https://en.wikipedia.org/wiki/Theory_of_constraints https://en.wikipedia.org/wiki/Theory_of_constraints [2] https://en.wikipedia.org/wiki/The_Goal_(novel) https://en.wikipedia.org/wiki/The_Goal_(novel)

omginternets 8y ago

So basically: they optimize for throughput, not latency.

Consultant32452 8y ago
This reminds me of the story where a Houston airport kept getting complaints from airline passengers that it took too long for their luggage to arrive. So they moved baggage claim farther away. This made travelers walk farther to get to their bags, but have a shorter "wait" time. Complaints dropped to zero. I wonder if there is a cultural difference there, where throughput is understood to be better than latency or something. https://www.nytimes.com/2012/08/19/opinion/sunday/why-waiting-in-line-is-torture.html https://www.nytimes.com/2012/08/19/opinion/sunday/why-waitin...

joewee 8y ago

This explains why Japanese train conductors make a big deal out of delays of a few seconds. It’s very common to hear announcements like “sorry we were delayed by 20 seconds because someone was holding the door.” Because that delays the entire line and all connecting trains by 20 seconds. And I’m sure these delays are tracked to measure performance of the conductors.