Leo, it was by TimeTable and Train Order. You checked your TT to see if any other trains were scheduled on that track at that time, you had to await up to 12 hrs after their scheduled time if they were late. If at a depot or other location where a register book was located you checked the register. You consulted your train orders, to see if you had any other trains to wait for, esp extras that were not in the TT. You checked the markers, either lights or flags, on the train that passed, to see if they had another section following. You also knew your place, what class was your train and your superiority. With that information you knew the pecking order, where you stood in the scheme of things. You carried your rule book, so you could consult it at all times. And sometimes you waited.
If there were no other trains scheduled on that track at that time, you had confirmed all scheduled trains had passed, you had no orders confirming extras or work trains that might be in your way, then and only then did you depart the siding and proceed to your next stop, meet or siding.
Doug Harding
www.iowacentralrr.org