I recently toured a very nice garden railroad in a botanical gardens where the track and ballast were built on top of wooden subroadbed strips, attached to stakes in the ground, up to 18 inches off the ground. The track was screwed down to the subroadbed, and dirt and rock were then filled in under, beside and above the trackwork. It reminded me of building subroadbed on risers with open-grid benchwork on indoor layouts.
Most of the books I've looked at, though, show trackwork being laid on improved earthen subroadbed. This method obviously works for them, but what are the pros and cons of using wooden subroadbed in this fashion? I'm in dry West Texas, if climate and/or moisture are factors. Thanks for your time and consideration,
Dusty
Welcome to the forum,
I would suggest going back a few months on these pages, there are several postings discussing exactly what you ask. You should be able to find several techniques done by members of this forum. In your climate area, I think, you should have little trouble so long as you paint or otherwise treat the wood.
Tom Trigg
I don't know if my info will apply for you because I live in Rhode Island, but I used pressure treated 1x4 as a sub roadbed on two previous layouts and they only lasted about 5 years at best. A plastic based board would most likely last a lot longer, such as Trex or Tuff Board. Due to a bad back I am now rebuilding so my layout is at waist level using the same methods you would to build a deck minus the deck surface. At that point I lay on a cover of galvanized 1" screen covered with weed block. The track is then layed on Tuff Board that is put down in a ladder fashion. The surface is then filled in with ballast and dirt/sand/rocks/etc. This system is great for the ability to have access to wiring underneath for a bus and block system along with low voltage lighting for the buildings. Seems to be working well so far.
In my area the only wood that is reliably ground contact rot resistant is pressure treated pine. PT pine is terrible stable and I have seen 4x4 posts do a 90 degree twist. Its gets worse with thinner material. As said above, there are a few plastic and composite materials available that are much better adapted for roadbed.
my article on Tufboard ladder -
http://www.grblogs.com/index.php/2008/12/13/ladder-track-support-systems?blog=25
and a layout using it -
http://www.grblogs.com/index.php/2008/12/12/my-7-8n2-layout?blog=25
-Brian
Thanks to everyone for their replies so far. I guess I didn't ask my question very well - I'm not asking about what materials to use as subroadbed, I'm more interested in WHY you would choose building on wooden (or some other material) subroadbed, versus laying track and ballast directly on dirt and gravel.
Thanks for helping out a newbie.
Dusty:
As much as I enjoy my ground level layout, I'm beginning to think I should have built it above the ground.
Arthritis and a bad back are making it harder to enjoy the trains. Crawling around on the knees is not what it used to be 50~60 years ago. Age and health issues are among the most common reasons for elevated systems (not all "elevated" systems are done by us older gentlemen.) Some of the younger crowd prefer the looks of elevated systems. Myself, I prefer the look of a ground level layout, but am beginning to appreciate those layouts where one can stand up to operate.
Ground level roadbase on stable, undistubed soil is fine but when you start building above grade you run into issues. Most disturbed soil can take years to settle. Having a firm base is a must of good trackwork. I have seen plenty of layouts where this was not taken into consideration and they result is sloppy trackwork with constant derailments. Not a fun way to run trains. Give your track a good solid base and you'll have few problems.
Dusty --I live out in the country in West Texas (the San Angelo area) and I used a post and bench similar to what you described using PVC and 4"/6"hardi board for 3 primary reasons.
First....deer and other varmits, including the elk that got out of the neighboring ranch.
Second....to allow me, another newby, to establish and then reset the grades fairly easily as I figured out what works and doesn't work in my starting design.
Third....to deal with the enevitable settling that comes when you fill in about 100 cu yds of topsoil. The post and board and the ladder system mentioned above both can take some settling without movement so all that is needed is a little more dirt.
If I rebuild some time in the future I might do a ladder system, but because of the deer (elk) et al, I stick with something more substantial than a trench of 1/2 minus and crusher fines for roadbed.
Mark
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