How do you build a pile trestle from scratch ?

During a discussion of the OB Pile Driver demonstration on the Cumbres and Toltec, someone asked me a question, I couldn't answer. It's easy to see how you would drive a pile when you have an existing track where you push the pile driver into position and are able to set up everything by the book. But what do you do when you are building a new trestle and don't have a solid platform to position the equipment? It's not like you can drive a set of piles (a bent), lay track to them, then move forward to drive the next set. OB and its steam supply are heavy! Is the trestle initially built with the bents temporarily on top of the ground, so that you can construct the entire span, then you come back and drive piles into the ground with a pile driver?

Building the trestle at Los Pinos must have been an adventure!

Bill Kepner