In 2.0 we're getting the power to assign each train station it's own priority (LETS GOOOOOOO), but what do we do in the interim if we need similar functionality? I'm mostly thinking of mods where you have byproducts which are used earlier in the production chain, and you'd like to have their output(s) prioritized over that of a mining outpost. Space Exploration and it's stone obsession comes to find. As the title suggests, I think this kind of functionality could be simulated by adding an additional signal that tells potentially incoming trains to skip it when they are at full capacity. This would make it possible to do something like "Copper Load T1 -> Copper Load T2 [new signal] -> Copper Load T3 [new signal] -> Copper Unload". Trains will always go to Copper Load T1 if it has enough items to be enabled, and when they are done loading they then skip T2 and T3 since they no longer need to be loaded. If T1 isn't enabled they'd go to T2 for loading, then skip T3 to go straight to unload, etc. Technically you can do this now by just letting your trains run the full route, but it's not very efficient.

I was going to make a fork to add this functionality myself but I figured I'd check with you first to see if you'd be interested in making it a feature in the original before I jump the gun.