I'd think prefabricated concrete spans would be involved. Pilings or piers would be a different story. On most concrete pile trestles I've seen, the bents so not have any reinforcement between spans like a wood trestle. However, we're talking about a 50-foot-tall trestle here, and assuming 30' concrete girders that's about 19 50-foot piles all-told.

And at that height, downward loading wouldn't be as much of an issue--rather bucking, or failure in which a vertical member fails laterally before failing at its conventional compressive limit, would be the biggest design constraint. Wonder how they'd address that...