Factorio Forums

What?
Pleas look at attached picture.
There are three rail crossings which looks very similar. And one Rail Chain Signal with weird behavior.
Let's start with that first one, it works correct.
Add a second track under the upper horizontal one, and get that second crossing.
One signal don't work (flickers green-yellow-red) - it's marked in picture.

So I taught it's to near to lower horizontal track. If so, I wouldn't report it as an bug. But on an other place I found a crossing like the third one.
The signal is at the same place as in the other crossings and just work.

What I expect?
It may even work in the first one and neither in the second one nor in the the last one, because of the horizontal track.
Or it may work in the last but not in first and second because of the track switch.
Or it should work in alle tree cases.

I duplicated this in 0.17.42, and found a simpler case where the bug appears. If there is only a short straight track after a diagonal crossing, the signal can be placed close to the crossing. If there is a longer straight track, the space closest to the crossing becomes invalid, even if the farther spot is also made invalid by a straight+curved switch track. In the attached image, you can see which signal spots are considered valid in each configuration.

Thanks for the report, fixed for the next release.