Attached are a few pics of a short, elevated section I made to span my work table.
I used 1 X 1's to make a three-piece pier for supports.
I was using Fastrack and also used 1/8 " hardboard under the Fastrack for additional support. If you're planning on running any significant weight engines and rolling stock on it, I wouldn't trust the track, itself, to be of sufficient strength to support them.
I also used self-adhesive, automotive sound deadening material between the track and hardwood board.
You also need to consider how you're going to supply power and drops to the elevated loop.
