From the very beginning, I had always planned to have signals on the layout. The goal was to have a fully operational Centralized Traffic Control system complete with a dispatcher's panel based upon one of the Union Switch and Signal installations. The dispatcher would be able to control the entire railroad from a remote location, and trains would move according to signal indications. I studied whatever material I could find on signals and signal systems. I learned what the various aspects and indications meant and began to figure out how they might apply to certain locations on the layout.
As progress continued on the layout, I added signals based upon what I thought would be a typical CTC installation. All of the signals have LED's and are wired for operation. Then in 2004, I purchased the user's manual and related materials for Bruce Chubb's Computer/Model Railroad Interface (C/MRI). As I began working through the manual and designing the system, it became apparent that this project would require much more time and effort than I originally anticipated. The programming required to make even a small layout like mine operational simply seemed overwhelming. The manual went up on the shelve to be considered another day.
Fast forward almost ten years and I meet Gerry Albers. Gerry and his crew have created one of the most remarkable model railroads that I have ever seen. The Deepwater District of the Virginian Railway was featured in Great Model Railroads 2013 and the layout can be seen here: http://www.deepwaterdistrict.com/. The railroad features a fully operation CTC system that utilizes a program developed by Gerry. Information on this product and the related hardware is available here: http://www.signalsbyspreadsheet.com/. I attended several operating sessions on the Deepwater District and got to see the system in action. I then attended a clinic on signaling at a local hobby shop that was put on by Gerry and the hook was set. I had finally found a system that I could manage in terms of setting up the signal spreadsheets and installing the hardware.
In order to install the signal system, the layout has to be wired in blocks. The CWE is divided into two separate power districts and has many built-in gaps due to the hand-laid track. I used all the recommended wiring techniques when building the layout so it appeared there wouldn't be a lot to do in order to get the layout ready for signalling. All I needed to do was verify where all of the existing blocks were located and I could begin to plan what additional blocks would be needed. That's when the Nightmare began.
I disconnected the power district furthest from the power supply on one half of the layout to begin the testing. Surprisingly, the whole section still had power. So I disconnected the bus to the next session. Everything still had power. I eventually disconnected every district from the main bus- and the entire half of the layout still had power. There were three track feeder wires that ran from the terminal strip where the power came in from the booster connection that were the only possible source of power left. I disconnected the first two- and the entire half of the layout still had power. Finally, I disconnected the last one and the power was off. Half of the layout was receiving power from one track feeder wire. I'm sure it wouldn't have been enough to run trains, but power was there nevertheless.
After a lot of head scratching, it occurred to me that the power from that one feeder to those two rails took a long trip all the way around the layout. Out along the solid connection from the Sand Fork Branch, down through Big Chimney, down the feeder wires at Big Chimney, back up the feeder wires at Summit Springs- you get the picture. It became apparent that I was going to have to document the electrical connections on the entire layout if I ever wanted to figure out how to set up the blocks for the signal system.
So I spent the next two and half days under the layout tracing wires, drawing diagrams, cutting new gaps, and installing new feeders. Fortunately, I had just about finished the drawings for the signal system so I could use this as a reference when establishing where the new blocks should be. The drawing below shows the blocks and signals at Big Chimney (the red X's are feeders and the red O's are gaps) that were used for this process.
The benefit of all of this work is that I now have a notebook that contains wiring diagrams for the entire layout. The drawing below shows the master schematic for Zone 2.
And there is a separate drawing for each zone which includes all of the feeder wires and their locations. The drawing below shows the zone that is controlled by the terminal strip between Bus 2 and Bus 3.
Having these diagrams and the layout properly connected to separate power blocks is something I should have done many years ago. In fact, the lesson here is to do this as you build the layout, not after everything is operational and you've stored more stuff than you ever thought you owned under the layout. Believe me, your knees will thank you for this.