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Comment by renewiltord | Hacker News Reader

This is clearly written for an audience that already knows what's going on. I don't, so I'm curious. Is the difference between:

    outer terminus------>ny penn|alight|board new train|----->later station

vs.

    outer terminus------>ny penn|stay on train|---->later station

Why does the latter need more tracks? This seems intuitively obvious that it shouldn't, but maybe I don't understand this.

EDIT: Thank you to the commenters (who I can't answer because I'm rate-limited).

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It's about how trains are running.

Consider a rail network connected like A-B-C . With terminating trains you'd have one train run A-B-A, and another train run C-B-C. With through trains you'd have one train run A-B-C and another train run C-B-A. Terminating trains have to stop and reverse, which takes quite a lot of time because the driver has to go to the other end of the train. Through trains can just continue in the same direction, so it is a lot faster.

Because a through train occupies the track for less time you don't need as many tracks to serve the same number of trains per hour.

more importantly, if A and C are suburban locations, they probably don't need as much expansion as dogpiling everything in B, which is even more expensive because B is a block of some of the most expensive global real estate in the world.

The former (terminating lines) needs more tracks/platforms at the station, because turning the train around takes more time than stopping and continuing (through running) and turning around at the end of the line.

Issue is cost, through running could happen for much less cost. It would actually just be through running a little further at first and maybe integrated later. The current plan is to demolish an entire city block, the true motivation is for private gain.

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