This is a rather simplified explanation, but it covers all the basics you need to know for Rolling Line. Essentially, most signals have three possible colors. Green means "Clear to proceed", amber is "Caution" or "Slow", and red is "Stop". Kind of like a traffic light.

Some signals can only show red, and will simply be off otherwise. Semaphore signals use an arm instead of a light, with horizontal meaning "Stop", diagonal meaning "Caution"/"Slow", and vertical meaning "Clear". Otherwise, they all function pretty much the same.


When setting up (most) signals in Rolling Line, you have two possible zones to adjust, the amber and the red. If a train is in (or moves into) the red zone, the signal will display "Stop" (via either a red light or horizontal arm, depending on the type of signal you're using). If a train is in the amber zone, the signal will display "Caution"/"Slow", and if there is no train in either zone, the signal will display "Clear". Changing the length of the zones changes the ranges at which the signal will detect trains in each zone.


Signals also have "toggle source track" and "switch direction" buttons, which change the track and direction that the signal detects on.

Thankyou so much, you've explained it so well, I now should be able to stop those collisions.lol

I am finding that the signal switches rarely seem to work properly. My trains regularly blow through Red signals. I've checked the settings many times and added little "Enable AI" signs to make sure that the trains use AI. I've deleted and replaced the signals countless times and many of the trains still blow the Stop signals.

What I am trying to do is get two tracks to merge and have trains to reach the merge at similar times figure out who goes first and not just crash into each other.

And, it really shouldn't matter how I've set the track and detection settings -- if the signal is red, the train should stop.

This is very frustrating. Either I am completely clueless how to set up the signals, or there are severe bugs in the code.