[kovarex] [0.17.21] Train changes mind while path through intersection is reserved

[reduke]

Apologies if this has already been posted - I looked and searched everywhere I could find, but the only thing I could see was a similar bug from pre-0.16

Log file attached

factorio-current.log

(9.53 KiB) Downloaded 126 times

, savegame is here: https://drive.google.com/file/d/11XFB2A ... sp=sharing

Game will need to be slowed down to 0.1 or less immediately on load - there's only a few in-game seconds before the bug is visible, at co-ordinates: -1459, 555.5, zoom 0.455

This intersection was recently rebuilt, and there is 1 broken signal planned for deconstruction, which afaik should have no bearing at all on this bug. There is no further (de/)construction planned here, or anywhere else on the rail network.

The bug concerns "Locomotive Mougugy", which is the 2nd train to pass through this intersection after loading the save, travelling east-west on the southern most line.

It is following another train, and wanting to go the same path as it. As it is approaching the signal, it's desired path is blocked due to the train before. As soon as it's breaking point hits the first signal, it switches paths to take the north-west exit instead of the north-east exit. It reserves this path successfully.

As soon as the actual locomotive reaches the first signal, it changes it's mind, back to it's originally desired route, and stops from ~147kmh to 0kmh on a sixpence.


I have seen the aftermath of this bug several times, and was never able to find a cause, but this was the first time I witnessed it in full and was able to get the appropriate autosave captured.

I am running mods: "Blueprint footprint" and "DestroyEmptyChunks". "UPS-up" is disabled due to version incompatibility.

I have run console commands to get rid of pollution, turn down biters as much as possible, and generate some ore patches.

This game has a very large amount of active entities - it normally runs around 25-30 UPS on my PC.

Apologies also if I have missed something really simple

Thanks.

[reduke]

Just a quick update, don't mean this to be a bump, but I can confirm that this bug still exists in 0.17.21 - the same save file still produces the same outcome.

[kovarex]

It is a known property of the path finding. The train path finding doesn't take current speed into consideration. So it can change a path to a section, where it needs to stop faster then normally possible.
For this case, it can "magically" slow down as fast as it needs to not cause crashes.

We could probably adjust the path-finder, add a constraint to it, that it would not be allowed to consider a path that is blocked closer than the current breaking distance, but I don't feel that it is worth it at the moment, as it is happening quite rarely and doesn't actually break anything.

[Davv]

Isn't that fixed by 0.17.38?

[reduke]

Nope, this still occurs in 0.17.39

Thanks for the update kovarex - it would be really nice to see this fixed in future, as it really is immersion breaking, if nothing else.