I am building on NC red clay, which is very expansive. Any advice from someone who has done it would be most appreciated.
The simplest way is to just float your track in the ballast. The ground can expand as it wants to, and the track will just rise and fall with the tide, so to speak. You're going to have to do some occasional tweaking to keep things level, but that's typical regardless. I'm also on a rather expansive clay base (Bentonite). My track is anchored to a PVC pipe run under the track, which is then anchored to 24" rebar stakes that are driven into the ground. The rebar stakes stay where they're supposed to for the most part, but if I were to do it over again, I'd use something other than PVC pipe. It's round cross section makes it prone to ballast pushing it up out of the ground between the stakes.
Truthfully, if it weren't for my 2 kids and 2 dogs running around in the yard, I'd probably not bother anchoring the track to anything and let it freely float. But with the foot/paw traffic, it's beneficial to have the track held fast to the ground.
Later,
K
My track is/was located in Calif. White Clay, which moves when wet. I simply constructed a rock roadbed. Cut a “trench” 2 inches wider than the track, 4 inches deep, lined with gardeners fabric normally used for weed control. The fabric keeps the crushed gravel from floating away in the clay. I level the road sub bed about half to three quarter inch above ground level. On that I place the track and then backfill with crusher fines. So-Cal = lots of sun, little rain, small wind: So I have to tweak the rails every eighteen months or so. The only attachment to the ground is provided by Mother Nature: Gravity.
Tom Trigg
Kevin, you have mentioned pvc in several articles, as base for your track. Please tell me what dia. you use, as I intend testing that method on my new garden railroad. Details would be appreciated on track and pvc relationship. I intend planting vertical pieces of pvc, with 12" above ground, using pvc tees at intervals. Diameter is big question at this point.
Thanks for all the articles you have written in general.
I agree with this method too. I suggest using crusher fines, or "rock dust" for all ballast work. The stuff compacts nicely when watered, and has the right look for the scale we're using. Rock dust can be a little hard to find, but I find it worth the effort.
I'll say that the track on almost all garden railroads will need periodic attention to adjust for weather, vegetation, and the occasional pet. A floating track plan will allow you the flexibility to make these adjustments without major reworking.
I use 1/2" ID PVC conduit, laid under the track as a guide of sorts. It's held in place by tying it to 1/4" rebar posts driven into the ground.
The one thing I'd do differently today (and have re-done in places) is to double the amount of rebar posts. At issue is the round cross section of the PVC pipe. As things shift due to the natural forces of freeze/thaw and thermal expansion, the PVC pipe moves side to side. As it does this--because it's round--it tends to ride up over the ballast that surrounds it rather than push it aside. As a result, you get scallops between each rebar post where the pipe rises up. In some cases on my railroad, it's risen as much as an inch or so. (See my "GR Basics" Column in this month's--April--issue.) I've gone in and added more rebar, so they're placed every 2' or so, and I've noticed a definite decrease in things moving.
Combined with this, I've lessened the frequency of how often I attach the track to the PVC. When I first built the railroad, the PVC was tied to the rebar every 5 or so feet, and the track to the PVC every 18" to 2' or so. Now, that's pretty much reversed. The track is only periodically anchored to the PVC, about every 5'. This allows the track to expand and contract without "dragging" the PVC with it. It's still held down often enough to where errant feet, paws, etc don't disturb the track.
Bob,
My club is in Milton, Florida - so conditions are similar to where you are. I would recommend using 2" PVC Sch 40 pipe for the risers, a 2" x 1/2" reducing coupling on top of that. Drill the 1/2" through before attaching to the 2" post, then drill a clearance hole for a #6 or #8 sheet metal screw. Cut a short length of 1/2" to go into the reducing coupling (make it a little longer than you think you will need) and set this in the branch of the 1/2" tee you will use for the 'running pipe". I would recommend no greater than 18" using 1/2" pipe. For longer distances between posts I would recommend 3/4" or even 1" pipe. The down side to the large pipe sizes are they are less flexible than the 1/2". The reason for the hole in the reducing coupling is so you can drive a screw into the vertical pipe allowing for elevation adjustment.
Personally, I am going to use similar, but larger technique. I will be using 3" for risers, a 3" x 2" recusing coupling and 2" pipe for the adjustable riser. I will then use a more conventional ladder track base. I am also looking at splitting the hub on the 2" side of the recusing coupling and using a hose clamp or u-bolt in lieu of the screw. My height will also be higher than yours, at about 18" - 30" or so. If you know you will never move any of your track work, I would also suggest setting the posts in concrete.
Bob C.
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