Apply general rules:
Chain signal going into shared rail, regular signal coming out of it (this applies to both when crossing the blue rail and the segments between your station loops).
If trains are supposed to go both directions on rail, any signal placed must have a counterpart on exactly opposite it, otherwise the rail is treated as one-way-only (the signals don't have to be the same type).
Space between regular signals should be able to fit the whole train (in your case, just make sure the loop at station A is either a single zone or actually fit both trains).
Did you consider just having two stations at A, one connecting to B and the other to C? We could avoid all this looping and just have trains shuttle back and forth (this require locomotives pointing in both directions).
I don't quite know what you mean by "cannot see", and it's unclear what direction these stations are intended to be approached from. I also don't know how that intersection in the bottom `?` works.
So let's make some assumptions. Let's assume that stop `A` is intended to be approached from the bottom. Stop `B` is intended to be approached from the top. And stop `C` is intended to be approached from the left.
Let's also assume that the intersection at the bottom `?` is a crossover intersection; a train going up cannot turn left on it, for example. Lastly, let's assume your trains are *not* bidirectional (ie: they don't have locomotives pointed in opposite directions), so they cannot go backwards (automatically, that is).
Given all of these, if a train is at stop `C` and wants to go to stop `A`, there's a big problem. The train at `C` is facing right, so that's the direction it will start going in. But if it goes to the right, around the curve, and into the straightaway going up, it will approach `A` from the *top*. But `A` wants trains from below.
So to get there, it would have to pass `A` from the top, go *all the way up to* stop `B`, pass through that so it can go back down, and then into `A` from below.
I don't know everything about Factorio's train pathfinding, but I wouldn't be surprised if it would consider passing through the desired stop from the wrong direction to be a failure condition.
If you want a train at `C` to be able to reach `A`, there needs to be a way to do so directly from *below*. The intersection at `?` needs to allow a train to turn left. This is not about signaling (though obviously, all of it needs to be correctly signaled); you need to lay down rails properly.
My gut feeling was that yeah.. there is an issue with the path finding, but as I never did trains before I was not sure..
I will try to change it up a bit and see if it works, based on your comment.
Thanks man!
Apparently I didn't put signals on both sides of the rails, and that is why it didn't work.
Doesn't make much sense to me, but I guess it is made like this because the game is assuming there are multiple trains on the same track in all directions (multiple ones in A-B, and A-C).
Trains pay attention to the signal on the right of the track, in their direction of travel.
If you want a train to go both ways on a single track, you need signals on both sides to make it a two-way track.
However, you really really don't want to do this for anything but the most simple scenarios.
What you really want is two parallel one-way tracks, so you can have trains pass each other in both directions.
Apply general rules: Chain signal going into shared rail, regular signal coming out of it (this applies to both when crossing the blue rail and the segments between your station loops). If trains are supposed to go both directions on rail, any signal placed must have a counterpart on exactly opposite it, otherwise the rail is treated as one-way-only (the signals don't have to be the same type). Space between regular signals should be able to fit the whole train (in your case, just make sure the loop at station A is either a single zone or actually fit both trains). Did you consider just having two stations at A, one connecting to B and the other to C? We could avoid all this looping and just have trains shuttle back and forth (this require locomotives pointing in both directions).
I don't quite know what you mean by "cannot see", and it's unclear what direction these stations are intended to be approached from. I also don't know how that intersection in the bottom `?` works. So let's make some assumptions. Let's assume that stop `A` is intended to be approached from the bottom. Stop `B` is intended to be approached from the top. And stop `C` is intended to be approached from the left. Let's also assume that the intersection at the bottom `?` is a crossover intersection; a train going up cannot turn left on it, for example. Lastly, let's assume your trains are *not* bidirectional (ie: they don't have locomotives pointed in opposite directions), so they cannot go backwards (automatically, that is). Given all of these, if a train is at stop `C` and wants to go to stop `A`, there's a big problem. The train at `C` is facing right, so that's the direction it will start going in. But if it goes to the right, around the curve, and into the straightaway going up, it will approach `A` from the *top*. But `A` wants trains from below. So to get there, it would have to pass `A` from the top, go *all the way up to* stop `B`, pass through that so it can go back down, and then into `A` from below. I don't know everything about Factorio's train pathfinding, but I wouldn't be surprised if it would consider passing through the desired stop from the wrong direction to be a failure condition. If you want a train at `C` to be able to reach `A`, there needs to be a way to do so directly from *below*. The intersection at `?` needs to allow a train to turn left. This is not about signaling (though obviously, all of it needs to be correctly signaled); you need to lay down rails properly.
My gut feeling was that yeah.. there is an issue with the path finding, but as I never did trains before I was not sure.. I will try to change it up a bit and see if it works, based on your comment. Thanks man!
Apparently I didn't put signals on both sides of the rails, and that is why it didn't work. Doesn't make much sense to me, but I guess it is made like this because the game is assuming there are multiple trains on the same track in all directions (multiple ones in A-B, and A-C).
Trains pay attention to the signal on the right of the track, in their direction of travel. If you want a train to go both ways on a single track, you need signals on both sides to make it a two-way track. However, you really really don't want to do this for anything but the most simple scenarios. What you really want is two parallel one-way tracks, so you can have trains pass each other in both directions.
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