Currently, the mainline is operating from the Durango cutoff (approx) to just below Rico. There's no sidings yet, so I just have a test train that runs forwards and backwards over the line. This section includes nearly all of the hidden track, and I've wanted to make sure that was operating well before covering it. I had a little trouble over the winter with wood contracting, and despite my expansion joints the track did pop out in a couple of areas. Those were reworked (more gaps were cut), and they seem to be ok now.
Here's a few pictures of the real use of the Durango yard area (the upper level is raised while I complete work on the lower level). Sometimes I think the layout just provides a roof for all the forts and tunnels being created below it!