[0.18.3] Trains don't repath properly depending on track orientation

[19wolf]

I have a train stacker that only fills properly in certain orientations, in the opposite orientation, trains don't repath properly to fill the stacker. See screenshots and save file, let me know if you need more details.

[boskid]

Define "properly"

[TruePikachu]

I was going to complain as such as well, but e.g. in the 2nd and 3rd screenshots, the exit stacker has a train sitting at a blue chain signal.

[19wolf]

In the second screenshot, the train will sit at the blue signal forever. It's trying to path through the second to the top, which is closed by the bottom signal. It should path to the open bottom signal first, even though that top signal is closed. It does this properly in the first/fourth screenshots. It paths to the nearest open signal.

[boskid]

I was going to complain as such as well, but e.g. in the 2nd and 3rd screenshots, the exit stacker has a train sitting at a blue chain signal.

I saw that in game, but because of CN logic, in all stacker branches, there is equal amount of rail signals set to ReservedByCN - it is eiher first rail signal or last that is ReservedByCN. Since all legs are of equal penalty, pathfinder is free to choose which branch it will go and this issue is because train cannot go through path it choosed because first rail signal is here ReservedByCN. In Train Pathfinder there is special tie-breaking code that is required to keep decisions deterministic. It uses for example, Segment ID, Segment direction and since Segment ID may be different based on build order, choosen paths may be different. Since they are of same cost, it is Not a bug.

[19wolf]

Since all legs are of equal penalty, pathfinder is free to choose which branch it will go

Perhaps when they have equal penalty, they should choose the one with the nearest/first open signal? Or else is there some other way to create a 'specific order' in/out stacker?

[boskid]

Perhaps when they have equal penalty, they should choose the one with the nearest/first open signal? Or else is there some other way to create a 'specific order' in/out stacker?

Yes there is one solution: not keeping all stacker lanes at equal penalty.
- use more penalty in case of closed rail signal near the lane exit, for example by using double rail signals parallel,
- or: by keeping both (enter and exit) rail signals closed when given lane should not be used at the moment.