As you can see it is very inconsistent. Sometimes the area of effect of the power poles renders above and sometimes below the rails. In detail:
- most rails render below
- it's (for me) hard to tell if the railway tracks (the metal bar*) render above or below
- buffer stops always render above
- in some cases the railroad ties render above
Edit
The same problem occurs with electric mining drills and beacons. Turrets and roboports are fine however.
*english is not my first language