The PRR high voltage wires, these days being 138,000 Volts, (increased form the original 131,000), are two-wire, single phase, center-tapped circuits, with the center tap being grounded. That means that there are 138,000 Volts between the two wires of any individual pair, and 69,000 Volts from either side to ground. There are generally two sets of these two-wire circuits along the top of the poles. I imagine that if you are seeing 4 sets of wires (8 wires) at the very top of the poles, that at that point there are four, 2-wire circuits. If the extra 4 wires are lower down on the poles, they are probably the 12,000 Volt traction supply wires.
You could comply with the NEC and use 48 Vdc bare wires to discourage the occasional child or cat (or bat or parakeet) and by keeping the ambient room humidity above 80%. Children and other human vermin would be required to keep bare arms when viewing and touching the layout.
