After spending a little time in Switzerland, I started contemplating how complicated train scheduling must be even with modern computers to help. How this was done, say 75-100 years ago in a country with a reasonably high density of train traffic? Relatedly, how did a railroad decide to add/remove a station from a line or add/decrease number of train runs per day on a line?
The telegraph was invented because the railroads needed a way to communicate about deviation from schedule.
As an aside a then current engineering problem around 1900 was how to synchronize clocks that were far apart. Various solutions and protocols were proposed. Einstein was aware of that effort and it was one of the things that set him off thinking about time and how it related to movement.