[bobthepanda]

It has a timetable primarily because

- due to all the merging in and out throughout the system, trains need to be in the right place at the right time or merging delays will cascade throughout the system

- for purposes of employee scheduling, you need to make sure that the right employees are in the right place at the right time; generally a train leaving a terminal is being driven by a crew that had to come in from somewhere else.

[nerdponx]

It's also still useful as a general approximation for "how long should I expect to wait for the next train". Same with the bus lines.

[viraptor]

Isn't that a different idea than a timetable? "We're aiming for one train every 10min" and "there's a train at 12.10, 12.20, 12.30" are similar, but not quite the same. You can get your approximation without a timetable though.

[dredmorbius]

Tracked vehicles require centralised traffic management and scheduling as they cannot casually overtake one another as street traffic can, and setting switching points and clearing control blocks is required for safety.

Passengers transferring to other lines or transit modes may also appreciate predictability.

https://en.wikipedia.org/wiki/Centralized_traffic_control