Factorio Forums

What did you do?
In the attached configuration, I placed a rail signal expecting it to separate the block.
What happened?
The rail signal with highlighted placement did not separate the block (but did trigger a recolouring of the nearby blocks and changes the colour of the block it was placed on to yellow). No amount of placing or removing signals nearby ever causes them to resolve to be able to split their section of rail.
What did you expect to happen instead?
For rail signal placements that cannot ever separate a block to not be highlighted, or for the block to be separated (it looks possible to separate a block here to me)
Does it happen always, once, or sometimes?
Always.

That it doesn't divide the segments isn't a bug (per several previous reports) because the collision boxes of rails on both sides overlap.

I don't know if anyone has actually reported "why do the boxes even show up then?" as a bug though.

I've encountered the same issue with essentially the same configuration of rails as OP, the rails are just going the opposite direction, so the signals are on the other side of the track. When placing signals at the boxes circled in red, the signals don't work, suggesting that the signal placement boxes aren't pruned correctly.

Thanks for the report, this is a duplicate of 116405.