Layout Design Using Computer Aided Design Programs
by Larry Maier

With the advent of CAD software for layout design, there are new ways to translate your layout from the conceptual stage to the physical realization. As an example of the new possibilities that CAD software offers, this article will take you through a step-by-step process from concept to track layout. The particular software that was used for this example is “3D Railroad Concept and Design” published by Abracadata, although there are several other publishers with equally good products.

This part of the layout is for hidden staging track, and it requires the dual track main line to split into 4 separate tracks. The split is accomplished using a standard #6 left hand switch and a #6 three-way switch. After passing through the selection switches, the track must execute approximately a 90-degree curve to align with the actual staging tracks. Because of the odd angles in the three-way switch, the track radii to accomplish these turns are unusual fractions. In addition, straight track of the exact correct length must be used in order to assure that the curves, straight and switches all align. The design for these tracks is shown to the left. This picture is directly from the CAD program, with all of the track intricacies worked out.

The first step after finishing the track design is to print it out at a scale of 1:1. Since most printers can only handle 8.5 X 11 inch paper, this involves printing on multiple pieces of paper. Once they are all printed, they are taped together using basic Scotch tape. The entire template taped into place is shown left. A close-up of the finished template is shown below.

The next step is to transfer the track centerline from the template to the sub-roadbed. This is easily done by using an awl or other sharp pointed object. At each junction of the track centerline and one of the track ties, punch a small hole through the template into the underlying roadbed. The picture below shows how this is done:

After marking all of the track centerlines, the template is removed. You are left with a roadbed full of small holes. These holes are connected together using a pencil and ruler much as you did in kindergarten with connect-the-dots pictures. The picture below at left shows the process, while the one below right shows the finished result.

With the track centerlines drawn, the next step is to lay the cork roadbed. Split the cork in half as is normally done, flip one piece over, and align them center to center with both bottom sides up. Run a strip of 1” double-sided carpet tape down the middle, then use a sharp razor knife to slit the carpet tape down the cork centerline. This will leave you with a piece of cork with about ½ inch of carpet tape from the center out, and about ¼ inch of clear cork to the edge. Run a bead of carpenters glue down the exposed cork, then remove the protective cover from the carpet tape. Run the center of the cork down the centerline marked on the sub-roadbed, lightly pressing as you go. The carpet tape will give you instant adhesion, while the glue holds things for the long term. If you get it wrong, carefully peel it off and reposition it. Go back and install the other half of the cork next to the one just installed. Finish up by using a print roller or equivalent to pressure roll everything into place. The installed cork roadbed is shown below:

Finally, the track is installed in the conventional manner by centering it on the cork roadbed and using track spikes, nails, or glue to hold it in place. Shown below is the finished entry track into the hidden staging tracks:

The finished track exactly matches the original planned layout and it doesn’t require extensive use of protractors, rulers, compasses, etc. to get the final result. This technique also makes difficult track shapes such as spiral easements a snap.

If you are just starting out on designing your layout, it would be worth investigating the available Railroad CAD programs. Most of the vendors have free downloads that let you try the program before you buy. Typically, the downloads are fully functional versions of the software except that the SAVE function is inoperative.

Comments :

Some good ideas here in this how-to article ! Thanks. I use carbon paper to transfer the track centerlines from computer print-out (or trial sketch craft paper) to the train board below. You can still find it in some office supply stores. When you get the final positioning adjusted, simply slip the carbon paper under the track diagram and hand draw along the center line with a ball point pen. Easier and much faster than poking with nails or an awl and then having to re-sketch. The last few pictures didn't show up when I viewed it on Nov 10.

DonV

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