It's not really a new, crazy idea - before actual tram tracks were added, trams were generally created using electrification of roads, which somewhat made sense, but restricted those "tram tracks" to be placed on roads only, rather then in the grass next to the road.
Anyway, you essentially plan to create roads that look like tracks, and trucks that look like trains. Thus, they totally get mixed up with normal roads and cars, everywhere - not only the menu, but the depot too. If you are to build those faux tracks near a city, the city will eventually claim the roads and convert tracks to city roads. Citycars will spawn on your tracks.
Since trams exist, you will be able to have 3 tracks on one tile, though with very different behaviour. That will be quite thight I imagine.
Some problems are not that bad if you go the classic route of electrified roads. Your tracks can actually be just the tracks, so they would work on roads, and in addition you create roads that represent the gravel to put underneath.