Factorio Forums

I am looking for info on the following regarding train interrupt mechanics - some of these may be intuitive but I believe the in-game descriptions leave out a lot of the specifics (an aside, it would be appreciated if there was a more detailed explanation of the mechanics in game, perhaps in quick tips)

• Order of Precedence: If multiple interrupts exist, what are the implications of their order in the interrupt list? e.g., are they evaluated top -> bottom, does evaluation stop once a single interrupt condition is met..etc

• Evaluation of multiple "allow interrupt of interrupts" mechanic: Can you explain the algorithm that makes this determination? Is the list iterated only once? Does the last interrupt to be evaluated always "win" if multiple interrupt conditions have been met?

• When are interrupts evaluated: Is it on a timer (e.g., every 5 seconds), or some other condition (e.g., only when leaving a station)

• Are interrupts only evaluated when a train has a destination?

Interrupts are evaluated when a train is at a station and the waiting condition just became true. In this case, the train is about to leave a station. Before unconditionally going to the next destination in the schedule the interrupts are evaluated, and if one interrupt triggered its associated schedule entries are added in front of the next regular schedule, so the train will first go there instead of the next regular schedule entry.

My understanding about interrupted interrupts is that as default, the whole temporary schedule block added by some interrupt is executed completely before interrupts are checked again. This is only relevant if an interrupt adds multiple destinations. All these destinations are visited before interrupts are checked again. But if you allow interrupted interrupts, my understanding is that interrupts are evaluated even while working on the list of temporary schedule entries - after each visited destination, it's evaluated and might insert entries in front of the remaining temporary entries.

For reference :
https://factorio.com/blog/post/fff-389
https://factorio.com/blog/post/fff-395