As I noted above, and elsewhere, I think that manipulating the Hillock rules to apply to an embanked railroad is unnecessarily confusing, not to mention unrealistic. I've seen many embanked railroads. In almost every case, seeing something on the other side of the tracks is not possible unless one climbs up the embankment itself to peer over. Of course, there are also examples of EmRRs only a few feet above ground level that would not block such views. (But wouldn't such a low lying RR simply be treated like a normal road)?
Nevertheless, for simplcity reasons, it could be assumed that In game terms the embankment is essentially a wide 3/4 level wall. Wide enough to allow a unit to 'perch' on top, and see over, but high enough to block LOS between units not on top on either side of the EmRR artwork unless either or both have a height advantage.
Just my ruminations. I have no illusions the rule will be modified anytime soon, if ever. Best just to deal with the complications in the few times they come up in a game in the meantime.