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I'm not sure if this was reported or not; there are some signal related bugs open, maybe this is a side effect of another bug. So before I make a bigger, complete issue with save etc. I show just the screenshoots and a small explanation:
This is the situation. From player position the rail number 2 there is a train, that blocks the whole connection. But - as you might also see, when you think of this picture logically - this train can never allowed to be there, cause the signal that allows him to enter was red, cause the train before just occupied the entry signal, like on track 3, 4 and 5.

Here is the same situation as map-view with debug signals.

I saw this error now the first time, which wonders me, as this construction now works really near perfection since V0.16. So what has changed is the Factorio version.

And I can also explain how this happened 20 seconds before:
On the right side there are the 3 entry rails. The rightmost was occupied with the train which now blocks, but from the center rail a train drove into track number 3, which was at that time not occupied. In the moment when that train stopped, the rightmost train starts driving into track number 2. But the entry-signal for track 2 was still red! I saw this exactly, cause I was looking at this moment onto the map with this debug view open.

So what I saw was in end-effect, that a train, that drives through an allowed chain-signal-passage, that this train opens the path for another train into a blocked signal-path.

As said, I've the save etc. If you need more explanation just PM me.

PS: Maybe it's something with the very close to the end-of-train signals (the red signals track #3, #4, #5, where the orange chunk-border goes through)? This is done to enable entering faster into the waiting-area; immediatley when the train before moves, the next train can follow.

Trains have a small position window and not a fixed point when stopping at a station, so the signal might simply not have been red.

Loewchen wrote: ↑Sun Sep 01, 2019 12:01 pm Trains have a small position window and not a fixed point when stopping at a station, so the signal might simply not have been red.

The station is two trains further, train on track #2 waits here in front of a signal. And no matter if it is waiting in front of signal or stop: it does not move anymore.

I try to explain it shorter: Track #2 was occupied. Waiting train could not go in. Then other train goes into track #3. After that, the waiting train drove into the closed area through red signals.
The logical conclusion is this: something must have happened, so that Factorio thinks, that this track is free now. What could that be? For me as programmer this looks like it is a problem, that there are two (or more) methods to calculate, if a track is free and they are not perfectly equal in what they do.

PS: I'm sorry, after replaying the autosave this doesn't happen again. :/ Maybe you should sort it into "Pending"?

well... you do have 3 4 partially signalled crossings here. They might have something to do with this. With block viz on:

Yes, it's just one block. 3 rails goes in, 6 goes out. No magic involved here. The number of crossings doesn't count.

please check you setup if you don't have a similar construction bug as I did some weeks ago
viewtopic.php?f=18&t=62078

It's a while ago, but now I have nailed down a save, where I can really see, that the train is here going the wrong way. I managed to track that down, because it happened at this station nearly every 5 minutes.

As you see in the pic, it is nearly the same kind of station as above: The train to the right has been running over the blue chain signal below and then (instead of choosing the second row) it uses the third row. Which was and is red signal. The rules shouldn't allow that.

So it MAY be due to this kind of crossing (3 in, 6 out) that I use here. Nevertheless: it's a bug - but I will accept that it might not be fixed, because it is such a strange edge case.

I have also a save. (*) It takes about a minute or so, when a train arrives, which will go into these closed signal path. The save takes a lot of mods, and I haven't tested it, but I'm nearly sure, that all mods that are really needed to reproduce it is LTN. But I can test that also. But I would be interested, if someone cannot reproduce it.


(*) unfortunatly it's 136 MB and I cannot upload it here and I'm in holyday and have a very crappy upload speed. So: I'm on it and will upload it somewhere, but it may take some hours. Meanwhile I finish this post.

Link to the save:
https://drive.google.com/file/d/12EWMBt ... sp=sharing

Where am i supposed to look to find the issue? There is chain signal missing on the upper lane meaning train properly passed the regular signal and stopped at the rail chain signal.

Hm, copied that station from a blueprint. Like all the others. Seems, copy failed. I will have a closer look tomorrow...

Sorry...

disentius wrote: ↑Sun Sep 01, 2019 4:45 pm well... you do have 3 4 partially signalled crossings here. They might have something to do with this.
2019-09-01 18_38_32-Window.png
With block viz on:
2019-09-01 18_57_37-Window.png

The red chain signals at the tops of each image are in different places. The bottom image's is one position to the right.

I don't think this matters in the situation, but when I saw the first image my first thought was that that chain signal was too far to the left to properly enclose the intersection.