[desas]

> Terminating a train and turning it around takes a lot of space, space that is usually unavailable in a city center.

This doesn't happen in London in my experience. Trains don't turn around, instead every train is double-ended. The driver gets out of the cab at the terminus, walks to the other end of the train and gets in the other cab. They can do it faster than the passengers disembark.

[frosted-flakes]

That's what turning around a train means. The point is that a train at a terminal station is "occupying" a disproportionately long section of track, and as a result you need a multi-tracking and a ridiculous number of platforms to allow storage of trains to handle enough trains... while a through-running station can achieve the same capacity with just two tracks and 2-4 platforms.

[schoen]

Huh, I never thought of that as the reason for the small number of long-distance platforms in, for example, Berlin Hauptbahnhof (all through-running) compared to some other big-city stations that are terminal.

[Animats]

There are several solutions to turning around at a terminal. Sometimes there's a turnaround loop. Grand Central has two, one on each level. Older systems would detach the engine, rotate it on a turntable, and reattach it at the other end of the train. Double-ended trains are far more common today, since control from either end was solved long ago.