I built two of the Miami Valley Warren Truss kits. Both are double track, one is 60" and the other is 72". I added some homemade swivel hinges to one end since they span the doorway to my workshop. Here are some early photos (from 2012) when they were built and installed.
Hinge:
The 60 inch bridge is in front, 72 inch in the rear:
Here they are a year later (2013) with scenery completed: