The PRR Chartiers Branch - Lessons Learned
These are some notes I wanted to capture related to what I've learned while living with this layout for 7 years.

Extension Cords
When I was building the layout, I always had extension cords everywhere for the drill, soldering irons, bench grinder, etc. I kept tripping over them and they were always in the way. The construction phase can take quite some time and so during that entire time you wind up with extension cords on the floor which is unsightly and potentially unsafe. It would have been nice if I had integrated a 110-volt power line behind the modules with wall plates in the back under the scenery, into which I could plug the tools during the construction phase. This line could then be disconnected at the source when I was finished with the construction phase (i.e. when scenery no longer allows access to the 110-volt sockets).

DCC Turnout Control
Once I started operating the layout, I was bound to forget to move the points on one turnout and the engine triggered a system-wide shutdown. The problem with controlling the stationary decoders controlling the turnouts is that you cannot communicate with them while the system is shut down. I now realize that I should have provided a second DCC bus specifically for controlling the stationary decoders. That way, while the engine triggers the system to shut down when I accidentally run a turnout, I can fix the problem by flipping the turnout. Now what I have to do is manually move the engine off of the turnout to get the system to start up again. Of course, the engine's decoder still remembers the speed at which the engine was traveling when the system shut down, and the engine picks up where it left off. That means, invariably, the engine hits the turnout again before I have had a chance to flip the turnout. A real pain. This could be a real problem when there is more than one operator running the layout. The solution would have been to integrate another DCC bus to power the stationary decoders. This requires a separate booster or a Digitrax PM4.

Battery Power
Battery power in the engines is the way to go. It eliminates complex wiring, makes for smooth-running engines, and would simplify the track-laying step of layout construction. Regardless of which manufacturer's product is available, I will use battery-powered engines from now on.

Modular Construction
Although this layout did not need to endure an actual physical move to another house, the fact that I built it entirely modular makes its parts easy to construct in the garage and then move them to the layout room. Disassembly was equally easy, and allowed for the dirty job of removing the scenery (to preserve the wood) to be done in the garage rather than in the room. The downside of modular construction is that you always wind up having seams or gaps between the backdrops.

Layout Lighting
I still haven't quite mastered the art of lighting my layouts. I built the 4-foot fluorescent lights near the back of the layout, because I was worried that the overhead structure was going to be top-heavy and cause the whole backdrop to tilt forward (house rules were that I was not allowed to attach anything to the room's walls or ceiling). It turns out that this issue was moot, because of the U shape of the layout, which would have naturally allowed one side to rest up against the next side. Due to the lighting built the way I did it, the forefront of the structures, engines, cars, and scenery was always dark. Trying to supplement the lighting from the front when taking photos yielded a very unpleasant light mixture. Lighting really should come from above the viewer's head. A side note: a local exhibition-style modular layout used LED strips behind the front fascia (which was even with the front edge of the layout. The problems I saw were that the LED's were visible, and two, each of the LEDs created a shadow on the backdrop, so tree branches' shadows were duplicated a good number of times on the backdrop. A diffuser panel might have worked there.

The idea of hiding the electrical and mechanical things under the scenery while not being accessible from below the layout worked out well. It was always relatively easy to remove a section of scenery to gain access, and to then replace or redo that piece of scenery.