Factorio Forums

Link to video (deadlock happens around 15s)
I was stress-testing my 4-way intersection, and my trains deadlocked in an unexpected way. You can see the north exit signal being locked on the yellow state even though the train going this way stopped moving. This results in that path being reserved, and that intersection being completely locked. Removing and replacing the north exit signal fixes the deadlock.

Interestingly, all the instances I've had of this bug were with the same signal locking, even though the intersection is symmetrical. I'm not sure if this is just a coincidence or a side effect of the way my trains are routed, or if it is relevant to the bug.

Thanks for the report,

Looks like some wires got crossed somewhere in the code, the top right signal becomes reserved by error or out of sequence

This is not a bug, This is a design flaw. Only use regular signals at the end of a junction. Not at the start

Looks like some wires got crossed somewhere in the code, the top right signal becomes reserved by error or out of sequence

Are you sure?

Yttrium wrote:This is not a bug, This is a design flaw. Only use regular signals at the end of a junction. Not at the start

The intersection ran flawlessly for 40 minutes before locking when I tried recording the bug. It's not a design problem.

Regardless of the position and type of my signals, a yellow signal means a train is incoming. If a signal is yellow but the train reserving it isn't moving, then it's a bug.

Looks like this one to me: viewtopic.php?f=182&t=28660

Teraka wrote:

Yttrium wrote:This is not a bug, This is a design flaw. Only use regular signals at the end of a junction. Not at the start

The intersection ran flawlessly for 40 minutes before locking when I tried recording the bug. It's not a design problem.

Regardless of the position and type of my signals, a yellow signal means a train is incoming. If a signal is yellow but the train reserving it isn't moving, then it's a bug.

You're right, it's a bug. I assumed it was a design flaw because of the normal signals at the beginning. They are not necessary as trains will always consume that same block.

If you are able to reproduce deadlock on your crossing, please provide the savegame. Preferably before the deadlock around the start of your video. It will help developers to track down the issue.