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Discussion Starter · #1 ·
Hi, All

I’ve been reviewing back “raised bench work� posts, and have devised yet another variation on the theme. I ask the accumulated wisdom of the group to help me evaluate this notion. Is it workable? Am I missing something? Can it be improved?

Druthers. For the DC&M’s outdoor division, I wanted something elevated to spare my back and eliminate ground contact issues, and something I could fabricate and install by myself. Something that could be expanded or rearranged easily to accommodate changing track plan. Something not likely to get trampled by inquisitive deer. Andâ€"in deference to the timesâ€"something with minimal impact on the land.

Concept. Well here’s the idea, which I hope you’ll critique:



The half-inch plywood girders can be as deep as required for the intended span (e.g. 8� for 8’ span), and are easily curved laterally for a “flowing� roadbed:

“…where she’s narrow, she’s narrow as an arrow,
and she’s broad where a [bench] should be broad…�
--South Pacific (with apologies)


Construction. Eight-inch wide strips ripped from full sheets are spliced end-to-end to make girders of any length.
Girders are screwed to the treated 2x4 piles (legs) for easy repositioning in height. Treated 2 x 4 joists on 16� centers tie the stringers together and support the drainage layer. The trestle “footer� rests directly on the undisturbed soil in my back forty. Rebar spikes through the footer provide additional stability (think wind) if necessary.

The drainage layer is pure Richard Smithâ€"hardware cloth, landscape fabric, and a thin layer of quarter-minus road mix. Prefabricated or hand-laid track is set directly on (or in) the road mix and lightly ballasted with, um, well…ballast. A thin, easily renewable topping of sand or “real dirtâ€� provides all the “textureâ€� I care for.

Will this structure survive those extreme Montana winters? And hot summers? I think so. Frost heave should not be an issue, and in any event would be easily corrected. The elevated structure will drain and dry quickly enough after any rain. To test this notion, I’ve begun building a proof-of-concept module, small enough to be “portable�, but large enough to serve as a test bed for methods, weather resistance, etc:



The test bed is 48� long x 18� wide x 39.37� high. All wood is either pressure treated or painted with noxious CA solution, except for the rain cap, which will feel lots of elbows and fingers; that I will just seal or paint. I know it looks pretty yucky now, dripping green preservative as it does. But after three months’ exposure outdoors, it’ll be dry enough to paint with brown or hunter green latex paint. Then I’ll add the drainage layer, track, and ballast. More data when I have it.

OBTW, I have an ulterior motive for making this test bed nominally “portable.� I want to exhibit it at the All Scales Train Show at our mall in July. Perhaps I will be able to recruit a few good men (or women) there to help build the DC&M’s outdoor division.

Thank you for your time and suggestions.

Dawg
 

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Steve,
Don't have a graphics program to show what I mean, but looking at the pictures, it might be of benefit to place a "header" above where the "piles" attach to the "girders" and the outside ends of the "joists" to help spread the weight of the upper roadbed mass..

Sort of like a "T" affair, and I'd think about securing the piles to the girders (or vice versa) with plated carriage bolts...

Might be overkill, but it's a thought...
 

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Dawg

A very workable design imho.

As always, a few tradeoffs are involved and your need for lightness drives some of the compromises. Just a few observations not meant to change the basic design as it will only get unmanageably heavy.

I would be nervous of the strength of the small cross section piles - they are plenty strong in compression but given the ravages of weather and the weight of a ballasted roadbed they may not be as stable as you think to lateral forces no matter how well braced.

The girder made of plywood is also a concern. Raincap or not, I would fear moisture penetrating the open grain of the plies and causing delamination. Perhaps a marine grade plywood could be used but it is scarce and expensive. I would be tempted to bed the raincap against the plywood with a "red lightning" copper compound used by boatbuilders and to also treat the under edge of the plywood as well.

You do not show a curve but I assume it will simply be a wider version of the straight?

The structure once ballasted will be very heavy, perhaps too heavy to easily move. Only a test will prove or disprove. Of course, if you only need a couple of sections to be portable then ballast could be left off them. Having said that, if a section is not going to be moved, it could be made more heavily substituting pt 2x4 or 2x6 for the girders and pt 4x4's for the piles.

A word on cost. I do not know the American lumber prices (I do know they have risen since the USA restricted the importation of Canadian softwoods). Here in Canada, all the woods are readily available with pressure treated being relatively inexpensive. Cedar and redwood are both about double the price of pressure treated ... and commercial pressure treated is a bit more expensive and quite a bit more rot resistant then buying spruce and treating it at home with a preservative.

In short, I believe the idea will work.

Regards ... Doug
 

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Dawg

An additional point.

I built my own elevated trackage using 4x4 piles on 4 foot centres and 2x6 stringers ... cross bracing was 2x4 all wood pressure treated. I then used 2x2 on 1 foot centres to hold hardware cloth topped with landscape fabric and then about 2-3 inches of soil. I just waded through knee deep snow to see how well everything held up and discovered a problem.

In a place where a screen fence had been erected, the wind drifted the snow into a huge mountain at least 6 feet high on top of the benchwork. The snow was not evenly spread on the benchwork but sat against one edge. As the snow has melted down, it turned to ice and what once weighed a couple of hundred pounds suddenly became very heavy as it absorbed water. Eventually about 8 feet of benchwork gave way on the edge where the snow was piled, ripping away the girder and canting the 4x4s forward, the hardware cloth also ripped and that area fell against the fence toppling a section of screening as well. In other words, I need to rebuild 8 feet of benchwork, 8 feet of fence and relay about 8 feet of double track. I cannot see under the snow if it damaged a switch or how badly the track is twisted, if any is salvageable.

The moral of the story is ... build it strong not just initially but for the long term. You may not face the almost 200 inches of snow we faced this year but the weather is a problem for everyone in some way. Mother Nature has ways to make you pay for any shortcuts!

Regards ... Doug
 

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I understand the need for sideways stability, but I think the extra width of the footer and sway bracing sticking out beyond the width of the roadbed will constitute an irritating tripping hazard. Our constant companion, "Murphy", says that things that require your attention will always be such that you will need to stand where that footer is, or have to constantly cross from one side to the other.

Also, the base (footer and piles) need to withstand BOTH a lawn mower being banged into it as you try to get as close as possible when mowing AND a trimmer (string or blade) cutting the grass around it. If they are too thin, they will get destroyed.

In addition, the footer, if not WIDE, as well as long, will sink into soft earth. I have 4x4 posts standing on concrete patio blocks, some 2-ft squares and others 8-inch squares and BOTH have sunk and really screwed up my very carefully layed out grades.
 

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I think that your design should work outside. Just a note that you plan the width so that if a car or loco falls over that they don't topple over the edge and down to the ground. So keep the track about a foot from the edge.

Terl
 

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Although some of the following ideas may not meet your light construction criteria, I have included the information for other forum members who might be considering a raised railway.

Rather than plywood with a rain cap, might I suggest a façade made of 5/4 inch fence boards. They are sold at Home Depot in cedar, redwood or pressure treated lumber. Wood preservative is only required where the boards have been cut to fit. They have rounded edges which will not gather rain, are easy on the hands if you lean on them, and can be painted or left to color naturally.



The boards should be no more than a tie height above the top of your drainage layer. That way locomotives and cars will not catch the façade on curves. I used a spare tie as my gauge. After the track has been laid, ballast is added to the top of the ties and the façade. Although child labor was used to ballast the Nelson Yard, such practices may be frowned upon in your area.

If 4 x 4s legs, concrete posts blocks and patio stones are too heavy for your intended purpose, I would use a water resistant 2 x 4 for the base of your trestle. The ends of the cross braces would rest on the 2 x 4 and not on the ground where they would be more susceptible to moisture, insects and rot.

If I built a railway using you method, I would be tempted to include a hedge underneath to hide all the lumber.



Several people have mentioned 4 x 4 legs on patio stones, which is also our preferred method. The legs are crossed braced where the road bed is wide enough for that to be effective. In areas where the soil is undisturbed and level, the grass is lifted and the patio stones set in. In areas that are not level, a shallow square hole is dug and filled with ballast to level the patio stones.

In areas where the roadbed may be too narrow for two legs and bracing, the legs are wedged in concrete post bases with pieces of cedar shingles. The blocks are set on patio stones.



Note the sturdy step over set on crushed stone.

Our wide yards are built like decks with heavy lumber joists and sides. A façade is still used because it is difficult to offset the exterior of the deck by the height of a tie when using such heavy lumber. Because of the heavy construction the 4 x 4 legs can be bolted directly to the frame without cross bracing.

Although an added expense, concrete deck post bases are something to consider. When an area of the railway settles unevenly, perhaps due to frost heave, it is a lot easier to use cedar wedges under the legs in the post bases, than to try leveling buried patio stones.
 

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Discussion Starter · #8 ·
Hello, again


First, and most important, let me thank you all for the careful suggestions and warnings. I asked for advice, and wow did I get it! I am accumulating your ideas in a summary list (off line). I will try to incorporate as many of them as I can in another trial design before I commit to extensive building this summer. I hope you will critique the next "go around" as helpfully as you have this one.


And then let me apologize for the overlarge type in my original post. I didn't mean to shout. I'm struggling a bit trying to recall enough HTML to post things here, and I got the font size wrong. Given the number of tries it took me to get the @!!# pictures to post at all, I'm leaving well enough alone for now...


Again, thank you all. I'll have more soon.


Dawg
 

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Hey Steve !!!!
I'm on the raised roadbed bandwagon myself.. there's a thread here somewhere...

http://www.mylargescale.com/Communi.../1/view/topic/postid/10694/Default.aspx#10912
My 2 cents.
I built a section of my design for the raised roadbed system back in Febuary. The only thing of note (and I heard the same advice for Richard Smith as well ) is that they tend to hold snow longer than the surrounding ground. The ground heats up afster and melt off happens quicker. Also, on a warm day then a refreeze at night will form ice on the rails.
If you are dealing with really wintery winters bear that in mind. It will need to bear the weigh of multiple sowfalls and freeze thaw cycles.
Otherwise.. looks GREAT!
df
 

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No apology needed for the large type. My aging eyeballs rather liked it. For me it was great readability.



One thing you'll get here on MLS is lots of advice and many options to choose from.



Your module looks good. The idea of taking it to shows is good, if you can manage it. It looks a might heavy to me. Otherwise, I lack the experience to comment further on the technique.



This is a hobby (to most folks anyhow). Try anything. If it doesn't work, scrap it and try something else. That's part of the fun!



Carry on and have fun!



Michael
 
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