Trains without locomotives are weird with groups

[mm678]

I was trying to get rid of interrupts in order to import new interrupt settings from an updated blueprint. To do so, I got rid of all trains with the interrupt (that I knew of), but could not get the interrupt to disappear. It turns out that the interrupts were still part of a group that had only decommissioned trains (without locomotives) on some abandoned platforms. It was hard to figure out why these interrupts would stick around and how to get rid of them.

Apparently, if a train is added to a group and then all its locomotives are removed, it stays in the group, but is tricky to find. In the ui of other trains in the group, it will count toward the 'Number of trains in this train group' count. However, it does not show up in the train overview as part of the group.

[robot256]

Nice observation. I learned years ago that trains with no locomotives can have complete schedules and even be set to automatic mode by script. In that case, they produce the "No Path" error continuously. When a locomotive with a schedule couples to them, the locomotive's schedule usually overwrites whatever was left on the wagons. But I agree it might make more sense for wagons with no logos to have their schedule and interrupts erased.

If we had an API for altering interrupts, a mod could detect detached wagons and clear the interrupts. Actually we could do that now, since writing to the normal schedule API seems to erase all the interrupts.