Seeing it in action makes me wonder why no one had that idea sooner.

Two things that are quite annoying though:

1) Panning across the world when switching trains is annoying.
Please add an option to jump between trains without pan.

2) It follows "main" locomotive instead of forward locomotive.
Figuring out which locomotive is in front is a pain. You'd have to determine where forward is from speed a few ticks after a train left the station.
I think taking first front_movers or back_movers where speed is positive worked.

1) Panning can be disabled already: set transition time in mod settings to 0, it should work.
2) Thanks for pointing that out. I was sort of aware of that problem, but didn't know the solution. Will try to fix, don't know the ETA though.

Please try version 0.18.3, should be better with two-way trains now. Transition time from one locomotive to another is configurable in the settings. Set to 0 for instant transitions.

Works nicely, thanks.