Factorio Forums

Cannot place signals on the upper side of some rails:

You managed to badly confuse the hinter by implying that right part of your rails is of unspecified direction.
On picture it thinks that it should match the upper leg so shows only one direction hints for signals.

Even if it would allow you to position on the other side this wouldn't really work with set of signals as on picture.

If you add two signals on middle track then it should add hints for right side I think.

Better would be the helper shows only possible positions for signals, but placement is allowed everywhere as usually and not locked to the suggested positions.

Greetings steinio

Placing signal(s) in the lower left leg should fix it.
NaB.

No, placing a signal in the lower left doesn't fix it. This was just a minimal test case to demonstrate the bug. Maybe it was too small?

Here is a larger test case. It is a simplified version of my railway network, but it has the same problem. I still have the save file if needed. I would like to add a pass-by loop in the middle, but I'm not allowed to place signals on the upper side of the rails. So I built it elsewhere and tried copying the signals with a blueprint.
The lower signals work fine, but the upper signals just flash green/yellow/red. Another bug? If I add two signals on the right, then I can add finally the upper signals.

Will placing a signal in the middle fix it?
Could you upload your test map?

I've attached the savegame to this post.

Placing signal on lower left is not helping since it's still implying that middle part of track is two-directional but there are no signals anywhere on it.
I think I understand what are you trying to do but I don't think it will work here (and I do realize it works in OpenTTD ).

It seems that game is unable to figure out that middle block - it might do with how game manages blocks. This is also why even if you force signals in there they will blink - they think that it's an invalid position still. This block might be very confusing since it has entrance and exits on both sides and middle is two way.

Adding set of signals in the middle makes game notice that this part is two-way properly and all seems well then.

I would side with this being an actual bug - layout proposed is logical - it creates a siding for trains to bypass. And it's a quite simple one used in other games like OpenTTD.

Could not rebuild this exact issue, but found other questionable behaviour of the indicator. Ill try to find a recipe.
Reopened.

I increased the distance of rail direction check for signal building from 3 to 5 rail segments.

This means, that less confusion should be there, as it will happen less often, that the algorithm finds one direction end, but the other is too far for it.