NO-PATH with multiple trains

[Sudomeapizza]

-- What did I do/ what happened?
I didn't do anything, the things that are happening is two trains going into buffer stations, or "stacking stations", then going straight into the final 2 differently assigned stations.

-- What did I expect to happen?
1) if there wasn't an issue, then I'd assume that the train would just stop and wait at the signal, or just perform a dead stop in the tracks like if you switched the train from automatic to manual while in movement.
2) if there is a no-path issue, then i would assume it would perform a dead stop in the tracks like if you switched the train from automatic to manual while in movement. But it still continues to run like normal as if nothing happened.
3) or if it were normal, just slow to a pause at the next available red signal and wait it's turn

-- What is the frequency of occurrence?
This is repeatable 100% of the time.

I am using a modded save, but all of these issues are caused using vanilla mechanics as nothing about the trains, train stations, rails, signals, etc were changed using the mods i used. Thus attached a vanilla save with the same issue, and same layout as i copied it with a blueprint.

Youtube video example of the bug

In the attachments are the world file and log. To initiate the trains, just toggle the constant combinator.


If I had to take a guess at what is going on, the train is getting confused with the rail signals somehow where it thinks that there is no path when it's turned red, but then finds the path again almost immediately after saying no path. I would assume it's happening within the same tick but i can't tell.

[robot256]

Can you share the timestamp when the "no path" text appears over the train? It's hard to see in the video. It does seem like the trains behave normally overall.

[Sudomeapizza]

It is at 29 seconds
https://youtu.be/fXCumzSYl5s?t=29

[Nosferatu]

What I see:

The second train intends to drive through the buffer station at full speed as the first one did.
When it starts pathfinding the second leg of its journey it realizes it can't do that because the way out is blocked.
That's where the no path is thrown but is immediately resolved by switching to stopping at the buffer station instead of driving through full speed.

I think the train resolved the problem correctly.
The only problem is that it throws a no path witch gets catched by a ?mod? or is that an option somewhere?
and alerts the user.

[Sudomeapizza]

The first thing is that the video is with my mods enabled, but with the save file in vanilla it does the same thing (probably should've just posted a vanilla recording, I'll update the post with that later)

but even through the pathing of the train, it shouldn't be saying no-path since if it were anything else as it approaches a red light, it'd slow to a stop. but a No-path is always referred to as there is zero way, track missing or no possible path to get from point a to point b, but there's always been a path. just a difference in red lights in the path of the train

[disentius]

First: As long as you do not see the no path appear above the train, it doesn't count:)
Second:. your use of chain signals causes the very brief no path.

Change all chains to rails, and the no path disappears. the trains seem to work like you intend.
Proof:

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

Copy blueprint

[Sudomeapizza]

Thank you, That does seem to fix the issue!
I rewatched Doshdoshington's video on it again and yeah with your blueprint i see it now, i wasn't placing the signals accordingly, thank you for your help!

[disentius]

welcome:)

[robot256]

Yes, there's no reason to use a chain signal before a station on a one-way track. There might sometimes be a reason to use chains on the single rail connecting the two groups of stations. Does the problem still happen if there is a chain signal exiting the buffer stations?