Now that the switch machines on the staging level are installed, tested, and fully wired/operational (with the exception of the final model board installation), benchwork for the second level roadbed can be constructed. Rick came over and we spent this past Saturday building the stringers for the remainder of the main line!
This image illustrates the general approach we took. The design leaves approximately 9-1/2 inches of clearance between the bottom of the top level and the railhead of the staging area, which will be plenty to adjust train or locomotive consists. The main stringers here are 2X3 pine, therefore there is approximately 6" of clearance between stringers and railhead, plenty for even my tallest equipment.
After 6 hours with both of us working, we had completed the new stringer arrangement and could re-populate the staging yard. Here you can see the difference between the future Onondaga Yard area (to the right) and the open mainline running (on the far side of the studs to the left). The Yard will consist of plywood installed directly on the stringers. On the back side, the subroadbed plywood will be at the same elevation, but supported by small risers to allow the scenery to fall away a bit on each side of the mainline - much like it does in many open rural areas of Central New York.
Above is the CP 282 area with the top layer subroadbed installed. The staging at CP 274 is below. We used scraps of 2X4 and 2X3 from the wall construction as supports for this area of the staging yard since the lower-level stringers were not accessible. This is a good example of how you need to be flexible and creative with your benchwork sometimes - it is not as cut and dry as you imagine all the time! The most important thing is to constantly check the level and elevation. When building atop a layer that was carefully constructed to begin with, this gets easier and easier as you go along.
More to come as I continue installing the second level subroadbed!
This image shows a typical installation for a pair of the Circuitron 'Tortoise' machines. These come with a mounting jig, allowing the installer to locate the machines using a small hole drilled through the benchwork at the location of the throwbar on the turnout. Four pilot holes are drilled for mounting screws, and the machine is installed from below the subroadbed. I had to check the alignment several times in order to get the location just right, but it has worked out well so far.
This is the 'heart' of one of my interlockings, CP 295. This is the 'west' end of my staging yard, and this terminal strip is how I have routed a separate power suppy to the switch machines. While I used red and white wire for track power, I have used black and green for switch power, and will someday use blue and yellow for signal power. The heavier 14-gauge green and black wires lead to another terminal strip which is the location from which all my switches will be powered, and it in turn is wired to an old transformer set to 10 volts.

The temporary model boards for each end of the staging yard...
And, finally, a close-up shot showing the throwbar itself on a Micro-Engineering #6 switch in the staging yard. If you look at the close end of the throwbar, you can just barely make out the end of the steel wire that links the machine to the throwbar and moves the point rails. It's a nice set-up and worth the extra money compared to other machines.