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Comment by parpfish | Hacker News Reader

It seems to make the assumption that you’ll get any particular train instantly. Factor in expected wait time for each line and the local/express variants and the sheds will shrink substantially.

it’ll also get confusing because the sheds will change as a function of time of day

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That might not be an entirely wrong assumption to make. An office worker's working hours usually has some amount of slack, and people are willing to adjust their schedule to minimize wait time. No point waiting 25 minutes every day when you can get up 5 minutes earlier and wait basically zero.

The subway doesn’t keep to a strict schedule (it has one in theory but no one would depend on it), and has anywhere between 3 and 20 minute headways (time between trains).

You can sort of kind of get close to 1-2 minutes of slack if you have an app telling you how far away the subway is (CityMapper has this feature), but you can’t really time your sleep or known work hours for making a specific subway.

I mean super-digital people really do. If your train only comes every 20 min, you absolutely have your eye on the app and change the speed you eat breakfast in the morning, or decide you can reply to 4 more emails before leaving work.

There are tons of apps with live train countdowns. They're probably the biggest improvement to NYers quality of life in the past 30 years honestly, with ridesharing in second place.

Schedules are tough for a transit system to keep. Plus you aren't guaranteed to have the same walk to the station every day. Factor in maybe a couple light cycles of signals you need to wait for as a pedestrian to get down to the station, and your travel time on foot to the station can vary by a significant proportion, adding one or a couple three minute light cycles into the mix that might or might not hit for you. I try and anticipate getting to the platform at least 10 minutes before the scheduled train as a result. If I am closer to 5 minutes then I am rushing, feeling late, and stressed, and have missed plenty of trains in moments in this situation before.

Wait, I'm supposed to not cross the street when I don't have the light? Who has time for that? I got a train to catch.

Transfers take a very relevant amount of time, even during rush hour when the trains are running frequently. Aside from waiting on the train, which does not keep a strict schedule and can get delayed for many reasons there is the walking time to the other train, which can be a decent amount even in locations where you don't have to exit the subway to transfer. Factoring a minimum 5-10 minutes extra time per transfer is a safe bet.

You misunderstand. It's not about one seat rides or about schedules. Nobody knows the schedule in NY, the train is frequent enough to not care. But changing lines is basically a statistical 5 min of travel time each time you do it.

It’s still interesting/useful, though. Once you require factoring in average train wait times and stuff like that the project is going to be way too complex to ever be achievable.

for sure, it's still useful, but i think it might be worth some sort of down-weighting for trains that run less frequently.

for example, if the ratio of local:express trains is 5:1, the watershed should be more heavily influenced by what's accessible in 40 minutes via local.

this is also in part due to the way people use the subway in NY -- nobody looks at a timetable and says "i'll head down to the station to catch the 6:37 express" like you would in some cities with reliable timetables/schedules. in NY, you just go to the station and wait and hope the train you want shows up next/soon.

> this is also in part due to the way people use the subway in NY -- nobody looks at a timetable and says "i'll head down to the station to catch the 6:37 express" like you would in some cities with reliable timetables/schedules. in NY, you just go to the station and wait and hope the train you want shows up next/soon.

That was true 15 years ago, but it's less true today now that there's a multitude of apps (both the first-party MyMTA app and many third-party apps which are much better) which make this easy.

Even Google Maps gives train times in their directions, and they're mostly accurately updated as delays happen, etc.

I've used the arrival time on Google maps and it seems accurate enough but the A train run so often it's not really an issue so I rarely if ever look. Plus I use mta.info for updates to check for delays.

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