TL;DR
Flag a train as express/priority to give it pathing preference.What?
It's my understanding that once a trains' "ready" condition is met it try's to path and if not it jumps in a queue of sorts and wait's until it's turn and/or a path is open.My proposal is a switch to make some trains "express" to attempt to guarantee that they'll leave to conduct their route ASAP. Effectively it will jump it to the top of the stack, or potentially introduce a new "priority" stack that does the same logic as the "normal" stack, but first.
This could even be to the point where it can force/overwrite current signals instead of waiting patiently for a currently running "low priority" train to complete its journey.
Why?
This could potentially mean something low priority leaves (yet more uranium) whilst your factory hits a standstill cause your iron train is delayed. Or perhaps you wish to make your "science" trains have a higher priority so you're always researching.Obviously, this has the potential to jam your entire system if you do not manage it well (just like the current signals system), but this style of management is common in IRL train systems around the world.