Factorio Forums

When a train approaches a merge point, occasionally its yellow light can get ahead of another train merging from a different branch.



In this image all trains are not moving. The circuit train is blocking the copper plate train.
Pausing the circuit train removes the yellow light and frees the copper plate train.

I have seen this problem 5 times on my world with over 100 hours.
I have tried reverting to an auto-save to deterministically watch it re-occur, but have so far been unsuccessful.

My gut feeling says it occurs more when a slow train gets in front of a fast train (slow copper getting in front of fast circuit).

We already had reports of these problems, I am not entirely sure what causes this and I haven't been able to reproduce it, but since the train code has seen a lot of changes during the integration of chain signals, I hope this won't happen anymore in 0.12. I'll mark this as resolved, and if it happens again in 0.12 or later, please report it again.