Train crashes into itself on rare occasions

[Rattlembones]

Hello,

Factorio Version: 17.66
Creative Mod 1.2.0
Save file: https://drive.google.com/open?id=1FOVlZ ... sXNdf6VKbl
In the linked save file, the player is in a train set on automatic. The train immediately goes through three loops. In the third loop, the train crashes into itself. This is unexpected because the train does not crash into itself in what seems like identical circumstances in the second loop.
I've been working with this type of loop for quite a while and this seems to be a rare issue (bug observed in less than 1 in 100 loops).
Let me know if I can provide any more information.

-RattlemBones

[Loewchen]

viewtopic.php?f=23&t=62183

[Rattlembones]

Thank you for your response.
It seems the topic you linked is unrelated. In the loops in my save file, the train is not long enough to crash into itself, but somehow occasionally does. I would expect the train to either always crash into itself or never crash into itself.
Hope this helps!

_Rattlembones

[Bilka]

Doesn't really look like "fitting in the loop" to me.

[Rattlembones]

It does fit in the previous loop which is identical, and if you switch to manual it also fits.

[Loewchen]

Maybe it is caused by the adaptive length or trains, but I don't think it touches collision boxes, or it simply ticks over the collision in the first loops the same the character can move through walls when fast enough.

[Rattlembones]

I did a little bit of additional testing - here is a save file where the train successfully runs through the same loop 23 times before running into itself (takes about 2 minutes at game.speed = 1). I ran this for about 10hrs of in-game time before observing a collision, so it seems pretty rare indeed.

https://drive.google.com/open?id=1lXH0v ... VUAQ7YBivr

[Klonan]

I checked it, each 'loop' takes 281 ticks, and it changes its position on the rail slightly each time.

So some times, due to the updating and the collision boxes, the train gets through,
but other times, with a different 'offset' from the start of the loop, it will collide

I am moving this to minor issues unless there is something more actionable.