# Variation on Ladder Roadbed



## zr1rob (May 27, 2020)

First, I don’t want you to think my way is the only way. In fact, my way of building a roadbed outdoors is a modification of what I’ve seen others do. My way, which I call the “straight and narrow ladder” (SNL), works for me because I like flex track and since flex track inherently creates transition curves that look nice and allow trains to operate smoothly into curves. It's a relatively cheap and quick method of roadbed construction vs. concrete, wood/metal post, bricks, etc. 




































SNL as I use it is GROUND based. That is, it's meant to be constructed directly ON the terrain/soil. One might attach the upper part of SNL to posts high off the ground in order to have a railway running up high, but then it won’t be SNL. 


The most important feature of using SNL is its flexibility. If you don’t like the way the layout is constructed, it's easy to remove the roadbed and change it around with little trouble. Another important aspect is simple construction. You could (and I have done so) literally build a lengthy section of roadbed, lay down track on it and run trains the same day.













Having a method with this ability gives the modeler the freedom to avoid creating every bit of the track design only to find out later that the route is unsatisfactory from whatever standpoint, but you're stuck with the roadbed as designed. You could rough out a design, put down the straight sections, fit the curves, tack down the track and try it out in a short time without worrying that something that doesn’t look right can’t be fixed unless a lot of work is undone.


The SNL method uses several materials that are available at big box hardware stores, either inside or thru their online website. 


2x4 lumber
1/4” x2” x 8’ PVC composite trim
3/4” PVC pipe
2” deck screws


The amount of the materials list above is dependent on the length of track you intend to build.


The 2x4 lumber is used for two steps in the SNL process: 1) it provides the roadbed for straight sections and 2) it is cut into short 4” sections and used between the PVC trim on curves to keep the curves in line. 


The PVC pipe is cut to short lengths, beveled at one end, and used to hold the 2x4s in the straight sections from moving. The PVC pipe length you cut is dependent on your soil – for loose soil, make the pipe lengths long – 1’ or more. If the soil is dense and doesn’t move much, the length can be shortened. Experiment to find out what is ideal for your situation. Err on the side of longer is better because we don’t want the 2x4s wobbling out of line since they act as anchors for the curves. The PVC pipes are attached to the 2x4s with the deck screws. But first the 2x4 must have a hole cut into it the size of the pipe. Use a boring bit the diameter of the PVC pipe you are using. I used 3/4” PVC pipe so a 1 3/8” boring bit did the job. Go about 75% thru the 2x4, not much more – you will have to pound that board and force the pipe on the other side to go into the ground without causing the pipe to poke thru the side you are pounding on. Drive a deck screw into the side of the 2x4 about 25% of the way up from the hole and drive it thru the pipe. Do another screw on the opposite side. You will notice the pipe swivels back and forth lengthwise a bit. That’s good for slight expansion and contraction of the roadbed along with track movement. Unless the lumber is over 6’, you only need two pipes. Otherwise, put a pipe in every 3’ or so.

Here’s a video showing how to make the 2x4 straight sections with the PVC pipe attachment:







Now for the fun part. Find a straight section in the layout design and install pipes into a 2x4 cut to the length of the straight section. Place the pointy ends of the pipes attached to the 2x4 along the proposed route and pound it in. If the terrain requires it, dig down or fill where the roadbed will go so the 2x4 rests along its entire length on the ground. I’ve found that making the top surface of the 2x4 even with the top of the proposed route gives more stability and hides the PVC trim pieces used for the curves looks better than having the sides exposed. This will require you to dig a couple of inches deeper along the route. Remember: these pieces of wood are food for insects so coat them with wood treatment and let it dry before installing. 

Before filling the ladder:










After. Note the tops of the 2x4s are even with the grade, making it easy to attach track to them with nails or whatever.











More to come ...


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## Aflyer (Jun 17, 2020)

zr1rob,
I like it, very nice and simple as you said build method.
George


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## Pete Thornton (Jan 2, 2008)

You are clearly in one of the dry areas, so the wood may survive longer. 



> The 2x4 lumber is used for two steps in the SNL process: 1) it provides the roadbed for straight sections and 2) it is cut into short 4” sections and used between the PVC trim on curves to keep the curves in line.


I do have one comment.You space the PVC quite widely on the curves and the blocks are far apart. Proper track design (especially ladder types) suggests you support the track under the rails, lengthwise, so your PVC strips should be 1.5"-2" apart. With the big gaps and wide spacing, there will be subsidence between the blocks and you will end up with a roller-coaster. Any heavy loco will cause the same effect.


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## zr1rob (May 27, 2020)

*Building the Curves*

This post will show how to make the ladder for the curves. I took the pix in this post during one morning - 7/17/20. The time it took from the first pic to the last was about 4 hours. The only step needed after this is to ballast the track. I ran a train to end of track after the last pic was taken to see if there were any places that caused derailments. An Aristo SD45 was used because its trucks are plainly the most picky when it comes to bad track. No problems.


So here we go. First, you need a straight section 2x4 installed as explained previously in this thread:












Note how the terrain has been dug out about 2" with the width of 8" for the entire length of the planned roadway (the ditch on the left is the actual watercourse, the roadway is on the right):











Next, place a length of the PVC trim onto the roadway. Note: you want to use a length of PVC that will completely go all the way from one 2x4 straight section to the next. If you have to join multiple PVC trim pieces to get the required length, the same PVC glue used to join PVC pipes works perfectly and permanently. I always prime the joint first with "Purple Primer". Note that this PVC trim piece is actually 2, for a 16' length. You can see the joint to the right of the bridge pier.













I always put down the outer PVC curve piece first, just a habit. It doesn't matter. Now put a screw thru the PVC trim piece and into the 2x4 straight. Just use one screw now, near the end of 2x4 so you adjust the angle of the PVC piece. The top of the PVC trim piece is even with the top of the 2x4 and overlaps the 2x4 by a couple of inches. Later, after the entire PVC ladder is adjusted to the angle (grade) you want coming off the 2x4, put another screw behind the first:













With the outer PVC curve in place, attach short pieces of 2x4's to the inside of the outer PVC. It was suggested to cut the 2x4's width down so as to support the track better. I did this and it worked out well. (Thanks Pete Thornton!). Use 2 screws on the outer PVC piece and 1 on the inside to keep these short pieces from wobbling when you attach the track to them by nailing or screwing. I cut them down to about 2.5" in width. If you want superelevation, attach them so their top flat area is a little distance below the outer PVC trim piece's top surface. You can attach the inner PVC trim even with the top surface so there will be a natural tilt to the inside of the track. 












I put them in about 1.5 - 2' apart:














Now make sure your curve is to your liking and attach the other end to the next 2x4 straight. I'm attaching the other end here to a bridge abutment, but the outcome is the same - you are attaching to a fixed structure:












It is now a complete curve, it just needs the inner PVC trim piece. Don't let the outer PVC trim piece move while you attach the inner PVC trim piece. When done, the curve will stay in place:












At this point, you can fill in between the ladder with whatever fill material you use. I just used dirt and small rocks smoothed to the geometry of curve:











Now just lay down your track. I use flex track because it gives a natural spiral transition and is easy to conform to the ladder:


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## Tom Bowdler (Jan 3, 2008)

Maybe an optical illusion but I am troubled by your retaining walls which look like they are leaning outward.
A wall should lean toward whatever it is holding up a term called "batter".
Perhaps like the 2x4 lumber in your dry climate this is not a concern?
Tom


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