With what we have in hand, I'd like to go out on a limb here. Expect animal puns. You'll be warned.
Lets consider the movie showing only part of the services the ZTA shows, including all the railroads. We can assume there is commuter rail, subway, streetcar/tram, skycar, ferry, and bus service. We'll ignore the latter three, of course.
Commuter rail shows as a partial ring around the various climate areas of Zootopia, using RDC or EMU units (no engines), with some way of "hiding" the third rail. The downside is that it's all one rail... and it looks like it corkscrews in... although there's four tracks into what I'll call "Watering Hole Station". Not all the railway is shown, though... and that's a plot hole I intend to drive a EMD GP40WH-2 through.
So let's speculate this:
- Communter Rail is called "TRAX" and one of the lines is to the Bunny Burrows ("Hopper" service). I think the other lines could be the "Polar Express" and maybe a line that lets you transfer to "Anitrak" for "Piggsburg."
- Two levels of rail service would be available: Direct and Scenic. Scenic service would travel a ring railroad and switch off at two points. Direct service would be underground for part of the way and then tie into the other lines. The outer tracks at the station are Direct trains. The inners are Scenic.
- Scenic service gets delayed due to snow drifts in the colder climate zones and sand storm drifts in the desert climate zone.
- There's a ton of pocket tracks around. Ooooh woe when those trains break down...
