How to Use Train Signals
You might have a very long track going from one town to another and maybe you need a second train. Building another station with a different set of tracks can be expensive, which is you might want to use train signals to be able to have two trains using the same tracks.
A nice and easy way to do this is to create side lanes that trains can use to pass through at the same time. Go to the train building menu and select a track. Split your current track in two and drag the new track right next to your main one, then you connect it to the main track again. Check the icon tabs above the tracks, this will let you select signals, the second one.
When you select the signals tab, a “Settings” window will open. Select Yes to make a track One-Way and place two signals, one for each track of the intersection. Now, your trains will be able to stop and see if the track ahead is available.