By Gary Reighn (gary@reighn.com)
The O scale modules of the East Penn members who regularly participate in the train shows are classified into modules that are relay protected (to prevent collisions during operation) and those that are not. (The O scalers in East Penn have adopted a relay signaling/block protection system which uses the extra running rail to engage relays and provide automated block protection. For the technical details on this system, you can download the article by Rich Kerr: Automatic Control of East Penn Trolley Modules.) The layout is usually organized so that one segment of modules consists of all the relay protected ones while the remaining section(s) do not have relays. The relay protected sections generally require fewer operators to maintain safe operation of the cars, even when distracted by conversations with the show crowd. The unprotected sections generally require more operators to man the numerous control points and to ensure cars do not collide with one another especially when the operator is distracted. The relays also allow us to maintain heavy operation on at least the relay protected section of the layout when there are insufficient operators to run the entire layout.
However, in order to facilitate this arrangement, there needs to be a turn back loop in the middle of the layout where the protected modules meet the unprotected modules so cars can circulate from end to end of the relay protected section. It is the need for this turn back loop that forms the basis for this new module.
The other major consideration in module design, one which is frequently missed, is the means to be used to transport the module to the shows. If you can't fit the module in your car or truck, what's the point! You would be surprised at how many people build bigger modules than their vehicles will accommodate (present company included!) To fit my current vehicle, the new module will be limited to 50.5" in length. The width will be slightly larger (around 33") than my other loop (30") in order to accommodate the additional trackage and scenery. I plan to join the two loops together using "splice plates" so they protect each other and form one unit for carrying and such. This is purely an optional way to go as many members use wood or aluminum to form a series of shelves in their car/truck and then slide their modules in one at a time. Either way works fine.
Now for the track plan. Below is a drawing of the new track plan (not drawn to scale). It gives you an idea of how the module will look. I then create a full size paper drawing to work out all the curve radii and turnout locations. It always looks like you can do more based on the rough sketch. Once you actually do the plan to scale, all of that space you thought you had evaporates.
You will note that the left end of the module will contain private right-of-way (PRW) trackage and the right end will be street running trackage. Since many of the unprotected modules have street running (and vice versa for the protected ones), it makes sense to organize the module this way for maximum flexibility. We always try our best to mate street with street and PRW with PRW for obvious cosmetic reasons. Having an extra module that does the transition gives us additional flexibility.
[Note: The remainder of this article assumes you are familiar with or have a copy of the East Penn Traction Club's module standards. If you do not, you can obtain a copy from the East Penn Traction Club web site at www.eastpenn.org/standard.html. For more background material, and additional module and trolley building tips, visit the East Penn Traction Club web site's Modeling Tips page.]
The next several photos show the module in various stages of construction. (Click on the thumbnails for a larger view.)
 Photo 1 |  Photo 2 |  Photo 3 |  Photo 4 |  Photo 5 |  Photo 6 |
 Photo 7 |  Photo 8 |  Photo 9 |  Photo 10 |  Photo 11 |
Photo 4 shows the module with a top of 1/4" luan plywood installed. Unless you are planning on standing on the module, 1/2" and 3/4" plywood are overkill and add a lot of extra weight. You will note that the plywood overhangs the ends by the required 3/8". When two modules are joined, these 3/8" overhangs form the 3/4" slot for the leg to fit. Do not forget this detail. For more illustrations of this, refer to the standards or check out this article: Module Building Techniques.
For the roadbed, I decided to try a different approach instead of the usual homasote material. Since I would be laying rail on two different mediums (PRW and street), I needed two thicknesses of roadbed to account for the difference in height. I decided to use 3/32" and 1/4" basswood. This gave me just the right height difference between the section laid on ties and that directly on the roadbed. Photo 5 shows the basswood in place. Photos 6 & 7 show closeups of how the ties of the PRW section will mate up against the street trackage. The basswood is also easier to spike through than the plywood, which is very tough and bends a lot of spikes.
Photo 8 shows one of the completed ends of the module with a 3/8" by 7/8" strip of plywood glued under the overhang of the top 1/4" ply sheet. This piece forms the mating surface for joining with another module. Be sure to refer to the module standards for the appropriate dimensions of this strip for your module. If it extends down more than 1 1/2" from the top of the railhead, it will interfere with the leg. Photos 9 & 10 show how the module looks with all of the ties glued in place on the roadbed. Note the extra wide ties where the turnout will go. Photo 11 shows the ties painted with Campbell's Tie Stain. After brushing the stain on, let it sit for a minute and then wipe it off with a rag. If it comes out too light, repeat these steps until you achieve the desired shade.
Please send any questions or comments to gary@reighn.com.
Copyright 2001 by Gary Reighn. All rights reserved.