...."split phase" is single phase...
There are limited instances where there is 60Hz power on the track as a grounded conductor, but those are 60Hz traction power systems, like the New Haven-Boston part of the North East Corridor.
BTW and going into the weeds here-
IIRC the original New Haven RR power system was 25Hz traction with 60Hz signal and track circuits. It also derived the power system from wye-connected generation where one leg is grounded as a delta would be and the "neutral point" left floating. All that pre-WW1.