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By Gary Reighn (gary@reighn.com)
In order to use the relay-based automatic control system, it is necessary to make sure the left and right hand rails are electrically isolated from one another. This is one reason why I avoid the use of PC board ties in my street trackage. It just adds one more complication to keeping the rails isolated. The first step is to determine where to make the cuts. My philosophy is to keep the inside rail (the one that supplies the power to the trolleys) as continuous as possible, and put the gaps in the outside rail (the one that carries the signal). You can see from photo 1 how the frog at the street turnout is gapped. Photo 2 shows the gapping at the crossover. To make the gaps, I use a cut-off wheel in a Dremel rotary tool. This makes a nice clean cut all the way down to the baseboard. To make sure the gap never closes (and to prevent the car wheels from bumping) I insert a piece of styrene the thickness of the gap into each one. I then thoroughly soak the gap and styrene with CA glue. Once it has dried, I use an Xacto knife to carve the styrene to the contour of the rail. This makes for a nearly invisible electrical gap (see photo 3)
The other place you need to gap the outside (signal) rail is wherever you want a block to begin. I divided the turn back loop into two blocks by placing a gap halfway through the loop. This provides for two stopping sections in the loop. See photo 4 for a picture of how I gap the private right-of-way rail using the same technique as the street trackage.
Next up is installing all of the power and signal feeders. Each electrically isolated section of rails requires a feeder line. I prefer to put as many of the feeders as possible in the paved street section as it is easier to hide the wires once the street is paved. However, I will share my technique for hiding wires on the PRW section. Photo 5 shows a feeder wire soldered to the outside of one of the rails on the street section. Keep the solder below the railhead and it will be totally invisible once you pave the street. The same technique can be used on the PRW section. This will also be fairly well hidden once the rail is painted and the track is ballasted.
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Once all of the gaps and feeder wires have been installed, we can begin paving the street. Since I am trying to represent an asphalt street, I will be covering the entire street with one material and coloring it all the same. The material I am using is something I have used before with very good results. It is a material called ScaleCrete from CS Designs, 140 Brockton Pl, Valparaiso, IN 46385. (The product is available from Walthers if you cannot find it at your local hobby store). I like this material because it has a great texture (it appears as though sand or some other aggrgate has been added to what is probably a plaster base.) It is also hard as a rock. This is the first time I will be using this material right up against the running rails. As a result, I am taking extra care to make sure it does not sit above the rails in any place. Although I have not tried this myself, according to the manufacturer, you can work with the material after it has hardened by wetting the surface first.
It is very important to properly prepare the surface you will be paving. First, I paint everything with a thick latext paint (any color will do; I use a dark brown which I also use underneath any ground cover) to waterproof the wood and homasote base. This helps prevent unintentional warping. The second preparation is to erect forms along the sides to hold the ScaleCrete. I use some thin strips of basswod for the forms and make them high enough so they are just below the railheads in height. You also need to put some temporary "dams" in place where the road meets the end of the modules. I tape sheet styrene at these locations. This results in a smooth finish once the paving material has dried. The last prep work is to coat any exposed spikes with a sealer. If you do not do this, rust spots will show through the paving material where every pike is. To seal them you can either paint each one with a thick oil paint or coat each one with CA or epoxy glue. Photo 1 shows the module prepared as mentioned above. Photo 3 shows the results if you miss coating a few of the spikes. Unfortunately, these spots will still be visible evan after I apply the black india ink wash I use to color the asphalt streets. Photo 3 shows the wooden grade crossing planks I installed before paving where the road crosses the PRW track.
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Please send any questions or comments to gary@reighn.com.
Copyright 2001 by Gary Reighn. All rights reserved.