I wrote some open source software[1] many years ago for mapping out bus routes, their stops, timetables, and everything else. It's pretty old and probably only runs on linux.

It will let you generate GTFS data (the standard for transit), and then there are OSM importers for GTFS data.

The nice thing, is that since GTFS data has routes, stops, timetables, holidays, ..., it will work with any of the routers with OSM.

[1] Subte