Factorio Forums

In the attached save file, I'm standing right next to a train. If I instruct that train to go to the station "Empty Pickup" it reports "No Path". I'm not clear why. It should be able to select the right track at the first switch where it can make a choice, the left track at the second switch, and from there get to "Empty Pickup". How should I adjust my signalling to make this work properly?

I'm totally confused now.

The save attached to this post was taken a little later, the train setup is basically identical: Cyan is still northbound up its "two way", pretty much keeping out of the way, and Yellow is trying to get back to "Empty Pickup". All I've done is to add the necessary switches and signals to get a third "two way" to service the new oil fields discovered to the west. But with these changes Yellow is now capable of going to "Empty Pickup" just fine.

Someone please explain. What's the difference?

As an editorial note on this factory, I'm very well aware that it simply doesn't need that sort of oil input, not at the size it currently is. I'm just doing this to try and learn how rail signals work, by getting multiple trains, each serving a single "two way" to one or more oil fields.

dgnuff wrote:In the attached save file, I'm standing right next to a train. If I instruct that train to go to the station "Empty Pickup" it reports "No Path". I'm not clear why. It should be able to select the right track at the first switch where it can make a choice, the left track at the second switch, and from there get to "Empty Pickup". How should I adjust my signalling to make this work properly?

I added a regular signal on the south side of the track your train was on and you were near in this save. Just to the west of where the Y is.

In your second map, the signal on the north side of the rail, opposite of where I added one on the south side, had been removed. I assume that was the fix.

Yea its because the rail segment the train is standing on only allows trains the other direction. The signal in front of the train makes the segment to only allow traffic westwards.

Your other save doesnt have this signal anymore. The segment the train is standing on is now also 2 way, because how you put signals on start and end.

The other signals are good btw. 2way rails are tricky because you never know which side of the rail to put the signals

Thank you both for your responses, I think I have a better understanding now.

@Mr Tact, I tied putting a signal on the south side of my red one just west of the Y, and noticed several things. Firstly, I am not permitted to put the signal any further west than directly opposite the one on the north side. Secondly, the placement spot directly opposite was white while the others were all green. I'm guessing that this means that a pair of signals on opposite sides of a two-way section of track are linked. This is confirmed by my third finding, it only works if the two signals are directly across from each other.

That said, in my current use case, I should never need signals on a section of two way, because there will only ever be one train on it, since each train is assigned to its own section. I should be able to remove that signal completely, since the signal for west-bound trains at the crossing will prevent a second train from entering that section of two-way track.

@aober93 you are indeed correct, two way tracks do take a little care to set up. It appears that a single signal one one side or other of the track makes it one way only, while a pair of signal opposite each other allow two-way traffic.