Conduit? What's THAT ;-? Only exposed (bridge crossing, etc) parts are in conduit.
Conduit is typically used along the entire length of most railway builds I have seen. Most recent railway builds have been multi conduit projects with up to 12 x 1.5 inch HDPE conduits plowed in by rail mounted cable plow. Your correct that steel conduit is used at bridge crossing or other exposed locations. I understand that when railway routes became popular some years ago for telecom that some railway/telecom companies did some research to understand where to place the cable with respect to the rail to minimize damage in a derailment. Apparently by placing the conduit 3-4' down and relatively close to the rail (ie: 2-3' from the rail) the steel rail will act somewhat as a shield to minimize exposure of the cable in a derailment. (ie: the car has to rip up the trackage and move the dirt to get to the cable) -Randy