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This has been an issue for several builds, but finally decided to spend some time to try and report it. ("Previous Log" attached, as I just switched to 0.17.52. My save from 0.17.50 is attached, and the log is from the last session on 0.17.50).

(Edit - This occurs in 0.17.52 as well, and have updated the title accordingly. Log file and screenshot from 0.17.52 is in response.)

I've been building a megabase for some time now. It's attempting 10kspm at 60ups with 12-24 trains and direct insertion. I'm still in the process of building it, but have it dumping science in to my old base to keep all of the trains moving just a little bit so I can fix any issues.

Base overview at max zoom (most of base captured, but not all). To do this, I've got large stackers leading into preloads queues for each station set. I have it setup to conditionally, disable the "input" stations to ensure that I get even coverage across the many stations that I have. To prevent train rerouting if all stations close, I have a dummy station that is behind a permanently red signal. This used to be accomplished with a single rail signal with a single engine behind it, but as you can see in the screenshot, it is now accomplished with a chain signal that by circuit network is permanently red.

What's been happening is that occasionally I'll come back and look at the interchanges, and find what's in the screenshot. Inexplicably, one of the trains has bypassed the chain signal, and is trying to get at the "dummy stations". Getting on the train, setting to manual, backing the train out, and resetting to auto resolves the issue (temporarily). Eventually, it happens again.

Detail of specific issue with rail logic. View of the stacker arrangement with stations. This block is repeated 15+ times down the main "train bus". Over the past few versions (can't tell you when it started), I have seen this happen several times (5 or 6). But I don't check often (as I'm focused on building, not production), and leave the base running 24x7 to ensure I have enough materials being made by the mall.

Interestingly, of the 15+ versions of this stacker and exchange, it seems to *only* happen (or mostly happen) at this one stacker exchange, despite sharing the same blueprint (recently updated) at all of the exchanges.

Thanks for the help! Let me know if you need more info!

Here's the save file (151MB - sorry...)
https://wetransfer.com/downloads/0c7ddf ... 456/1b1c5b

TSinge

And, it just did it in 17.52.

On the first screenshot of the train taking wrong path he bypassed 2 signals.
On the second one, it seems like the event only occured 1 time, he bypassed one signal. Was probably ready to continue.


There is no way i can load and check this (150MB ) map sadly.

But that makes me think it is a short event and i would try to look at the station that enable/disable if there was somewhere on the map a station named like the dummy station of this particular stacker. It would open and close shortly after when a train that was queueing arrive, long enough for a train in another stacker to cross one signal trying to reach it, and realise all station except the dummy is closed so it would repath toward the dummy.

If this happen once you got the second screenshot, it happens again you got the first screenshot.

Maybie it has to do with a station name also because it happens only in one stacker, with 15+ copy, maybe one of them you forgot to change the settings on one station to adapt the new adress and didn't notice if you assigned train with the minimap. This would cause it to mostly happens to the least used of the two stacker that has the same name ( but also a little in the other ).

hopefully it helps.

Hmmmm. I could see that happening. Most other places I've actually disabled the circuit conditions to "Enable/Disable" the actual stations of interest.

I'm thinking your right, this is not likely to be a bug...

Setup 1: dummy station after red 'rail signal' (red by circuit). Effect: train may path to dummy station and turn. For replay download trains-path-through-red.zip ---
Setup 2: dummy station after red 'rail signal' (red by circuit) with dummy locomotive. Effect: train may path to dummy station and turn. For replay download trains-path-through-red-2.zip ---
Setup 3: dummy station after red 'rail chain signal' with dummy locomotive. Effect: train may path to dummy station and turn. For replay download trains-path-through-red-3.zip ---
This feels like "Not a bug". In the end, red signal only adds penalty for train path finding. For true "do not path to dummy station" you would need to disconnect tracks, but this would lead to "no path" errors that you most likely want to avoid

For reproduction:
1/ Build blueprint (best way is using editor)
Copy blueprint
2/ (if using editor, resume time)
3/ Wait for train to be built and fueled by construction bots
4/ Change locomotive mode to automatic
5/ Train will go one full circle (to speed up) and on second lap it turns left

The train respects the correct exit through the chain signal as long as it actually can find any. If it can't find any path this way, it tries to find path ignoring the chain signal state.