Here is a blow by blow description of how it was decided where to locate signals, how many heads were needed, and what type signals.
First, David Hadley and I went around the entire layout and he made a diagram of the track plan and where signal heads were needed. This was before everything had been officially named and some of the names changed later. This first step was to locate where we needed signals. The first page shows a 2-track mainline that first has a crossover and then a right-hand switch on the track on the left side. (This is looking at the plan from the top down.) The other mainline track on the right passes the crossover and has a left-hand switch which enters a 4 track passenger yard. (Chicago Union Station)
On the left mainline track it calls for 3 heads, one for the mainline, the next for the crossover, and the last for right-hand switch. The colors on these three heads will tell which way the crossover and the right-hand switch are thrown. It will also tell if there are any trains on the selected route.
On the right mainline track it calls for a 2 heads, one for the mainline and the next one for the left-hand switch that enters the yard. All of these signals will be mounted on a 2-track signal bridge.
Further down is the location of a 3-track signal bridge just past the entrance switch to the yard. On this bridge, the first track has one signal as there are no switches that it can take going forward. It will be red, yellow, or green depending on occupancy of trains ahead of it. The next track is exactly the same with the need for only one head. The third track has 2 heads because it has a switch leading into the crossover so it will show if the switch is set for straight or diverging and indicate the occupancy of the selected route.
The yard will have all dwarf signals with the one at the beginning of the yard a 2 head signal which will show the mainline and the switch leading into the crossover. There will be four dwarfs in the yard, one on each track to indicate if track power is or not for the yardmaster.
The last 3 track bridge is bi-directional and just shows occupancy with singe heads over all tracks on each side. (It originally was noted to have a cantilever bridge over two tracks and a half-staff signal due to special vision problems with this location, but was latter changed to a 3-track signal bridge.)
This process was repeated foe every section of the layout. When that was completed, My son, Jim entered all the data into a spreadsheet. We then had to decide where all the blocks would be, had to number all the mainlines, number all the blocks, number all the signal heads and designate which direction they were facing, east or west. That took a fair amount of time, but when it was done we could take an inventory of how many heads we needed, how many of each type and size of signal bridges and all the other types of signals.
We knew we had to make all the signal bridges so Jim made a design template for each bridge that we could use during the construction process so the left hand would know what the right hand was doing so to speak. here is an example of the template for the first bridge described on these sheets. It shows all the signal heads are on one side. It has a 2-head and a 3-head facing in the same direction. So Alan 3D printed the heads, Jim wired and assembled the heads, cut the brass poles, I painted the Lionel 450 signal bridge, Alan laser cut the walkways, I removed the unneeded loops, painted the walkways, Jim assembled the heads and walkways to the bridge, I then masked and finish painted the bridges and individually painted the planks, and they were to have a final LED light check before installation.
Here is a picture of this bridge installed on the layout, but not lit yet. The railings, maintenance platforms, and pole end caps have not been added yet either.
A methodical process then began to build all 11 bridges with a solid plan. We knew who had to do what and in what order to bring it all together. Of the team, two were still working at regular jobs and I was the only one retired. As we kept saying about snags in our schedule "life gets in the way" and I had to remind myself that this is a hobby and we are doing it for fun. Alan's office is an hour from me and Jim's home is 22 minutes from me, not too bad in a major metro area. David is also retired and a half hour away. Plus we meet regularly for "train luncheons" so that is another way to exchange materials and give each other updates.
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