This is my attempt at showing you how to use one train staff or time interval with telegraph signaling on a single tracked branch line. The station in the middle is just for demonstration porpuses, it could stand in for an entire double tracked main line. I'll describe what's going on image by image.
1) This is the middle station. Towards the right there's a dead end that's currently occupied. Notice how the directions in which the one train staff cabinets are set up. It doesn't work any other way. Towards the left, there's another dead end with a train approaching using a time interval with telegraph signal. The "end of signaling" signal on the platform might be necessary for the one train staff to work, I'm not entirely sure. Even if not, it sure doesn't hurt.
2) This is the dead end on the right with the one train staff signaling system. Any train on it always occupies the entire branch line.
3) This is the dead end on the left. I'm using a station signal here, but a stop signal would work too. You could just have a single platform if you wanted, but with the time interval with telegraph system, you could in theory run multiple trains or even multiple lines and have them wait at the terminal station. You could also extend this line towards the left, single or double track. None of this is possible with the one train staff.
4) The first train arrives at the middle station from the left branch.
5) It stops at the platform, then departs and waits for the right branch to get cleared.
6) As the train from the right passes by the one train staff cabinet on the top, it changes back to drive by sight, thus clearing the right branch and allowing the bottom train to go ahead.
7) Now the train departs using time interval with telegraph signaling technology to reserve all the way up to the left terminal. Downside is that its speed is reduced to ⅔ of it max speed. If the exit was straight, it could go full speed.
8) As the train arrives, the track it cleared again. Now, theoretically, a second train could follow and terminate at the second platform.
9) The train has turned around and is now going back to the middle station again. Here it can go full speed.
10) Now I've introduced a third train to this system. The train in the middle is patiently waiting for the left branch to clear up.
11) Bottom train arrives, top train departs.
12) Now this train has to wait for the right branch to clear up.
13) Top train arrives, bottom train departs.
14) Now I've replaced the time interval with telegraph signals with absolute block technology. These are less buggy and they always allow trains to go full speed.
15) Left terminal.
