*[14.5] [Hanziq] Switching signal by circuit AND approaching train coincidently causes collision

[jonatkins]

Found a pair of trains, both running in automatic mode, collided at a junction.

train-automatic-collision.jpg (569.18 KiB) Viewed 3199 times

Might be related to the circuit network connection the blue train passed through? It's intended to hold the signals at red when there's a queue of trains trying to leave the copper unloading stations.

Managed to reproduce it from an autosave, so here's a save ~30 seconds before the crash (and save after, and mod folder, just in case):
http://www.jonatkins.com/factorio/bugs/ ... sion-0.14/

[Loewchen]

Can not reproduce without mods on your save.

[jonatkins]

Not surprising - the 'warehousing', 'add-loader' and 'compound-splitters' mods are integral to the train unloading/resource distribution process, so lack of these will change the train timing. Warehousing alone may be enough to reproduce it, or possibly replacing warehouses with steel chests (e.g. via a map editor, or somehow while paused, otherwise it'll affect the timing still)

[Loewchen]

Not surprising - the 'warehousing', 'add-loader' and 'compound-splitters' mods are integral to the train unloading/resource distribution process, so lack of these will change the train timing. Warehousing alone may be enough to reproduce it, or possibly replacing warehouses with steel chests (e.g. via a map editor, or somehow while paused, otherwise it'll affect the timing still)

Indeed, the crash was still too far off, I now have a save closer to the collision that shows the issue in vanilla as well (will upload when time).

My assumption: The signal turns red by circuit for the incoming train from the NW but the train has just passed the point of no return (or is exactly at it). The train from the south sees a not (yet) reserved block and enters, the train from the NW overshoots the signal...

This is a fun one

[Nexela]

Setting a signal to red does not guarantee that a train will stop as it could be past its stopping point. Might need a reverse circuit case to not set the signal to red if the signal is yellow.

[jonatkins]

Setting a signal to red does not guarantee that a train will stop as it could be past its stopping point. Might need a reverse circuit case to not set the signal to red if the signal is yellow.

Shouldn't be an issue - if a train has already reserved a path through a signal (i.e. it's yellow), then then the circuit will not force it red, and the train will continue through the signal. Other routes remain blocked.

Usually this junction works like this, no issues, but this once, after many hours (possibly over 100) set up this way, trains collided.

[jonatkins]

Usually this junction works like this, no issues, but this once, after many hours (possibly over 100) set up this way, trains collided.

Just for reference, trains collided again at this junction, shortly after updating to 0.14.7. Didn't catch it happening this time, but it looked exactly the same.