High Density Flexible HDPE Ladder Roadbed, Wood Trestles & Bridges

[John Carmichael]

Modern Flexible HDPE Ladder Roadbed, Wood Trestles & Bridges

This how-to video describes our modern flexible HDPE (High-Density Polyethylene) ladder roadbed, redwood timber trestles and bridges for the Cholla Patch Railroad in Tucson AZ. I highly recommend this type of roadbed for its ease and speed of construction, low cost, durability and beautiful curves.

Our non-traditional flexible roadbed is made from 3/4" thick HDPE house siding ripped into 20ft. long thin strips. I made the roadbed by attaching two HDPE strips together using short pieces of composite wood that I call "brownies". Video has useful design plans, graphics and assembly photos, and shows the advantages of this modern roadbed construction design. All the wood pieces are redwood, stained and sealed with Minwax dark walnut stain before assembly, then glued together with Titebond III secured with solid Brass Escutcheon pins (brads). I made printed templates of the pieces needed for everything. I attached the template drawing of the biggest trestle to particle board, making a sturdy wood jig for easy assembly. Wood is re-stained about every four years. I think you'll also enjoy seeing the detailed and extensive wood trestles and cool wood Bridges.

Feel free to copy, use or modify any of the images or video shorts you see here. I highly recommend this type of roadbed. I hope this helps you make your decision on the type of roadbed and materials you'll use for your own garden railroad. - John Carmichael

See my other projects here Cholla Patch Garden Railroad Design & Construction Series:

Cholla Patch Garden Railroad Design & Construction Series

 

[Paul M]

Looks very similar to Filcris, which works well, if you can overcome the expansion/contraction.
As an aside, I know a chap who is using aluminium ladders for the straight runs on his layout

 

[JimmyB]

Looks very similar to Filcris, which works well, if you can overcome the expansion/contraction.
As an aside, I know a chap who is using aluminium ladders for the straight runs on his layout

Looking at the price of Filcris, it is not cheap!

 

[dunnyrail]

Looking at the price of Filcris, it is not cheap!

Abreed, this is one if those products that using un recyclable products should have environmental price benefits for the manufacture and sale of the products.

 

[philg]

Looking at the price of Filcris, it is not cheap!

Looks very similar to Filcris, which works well, if you can overcome the expansion/contraction.
As an aside, I know a chap who is using aluminium ladders for the straight runs on his layout

I wholly concur about the expansion issues with Filcris - I have had to abandon its use on my railway because it wouldn't stay put.

 

[John Carmichael]

Don't use Filcris for the stringers of a flexible ladder roadbed. Filcris is NOT flexible enough and will not bend well for making curves. Filcris is more like a composite wood and has structural strength. HDPE is sold as non-structural house siding- like vinyl siding. That is why it bends so well. BTW, if you can't find HDPE house siding, you can use vinyl siding instead. It is a little more flexible, but is not quite as durable as HDPE.

TrexTrim is the material I used. It is PVC lumber but is very similar in all ways to HDPE lumber. It’s very flexible, but I don’t know if it is more or less flexible than HDPE. I bought this size: SKU: WW010618B. This measures: 3.4” thick x 5.50” wide x 18 ft. long (actual). It’s white with wood grains. I had the supplier rip each board into 1.75” strips for the stringers. Wider boards are available but all will need ripping. The supplier delivered the ripped strips to my home for a small fee. Website: Trex trim brochure - Trex Inc. - PDF Catalogs | Documentation | Brochures

 

[Paul M]

Don't use Filcris for the stringers of a flexible ladder roadbed

Mine seems to work well

 

[dunnyrail]

Filcris does work very well providing you accept what you are going to be faced with in terms of expansion. Track not too severely pinned or screwed down works very well. I have a short section that gets early sun and mives around a lot and this is on wood! To keep track in place I have oblongs of HIPS pinned in the centre of sleepers, this is smaller than the oblong that it sits in thus allowing the track to move in all directiins. As all track is held with Clamps that movement causes no issues as it is contained withing the track and board limits.

 

[John Carmichael]

Mine seems to work well

Hi Dunnyrail:
Your statements raised more questions than answers for me. I admit I'm not familiar with Filcris. Please tell us more.
Questions:
My concern about using Filcris stringers in a flexible ladder roadbed is its lack of FLEXIBILITY IN CURVES. Do you use it where you have small curve radii? If so, what is the smallest curve radius you have? Also, how thick is one of your Filcris stringers.? My HDPE has 3/4" thick stringers and the smallest radius I could make is about 4 ft. for my trolley line. (see roadbed photo below). Can your Filcris bend this tightly? When you buy the Filcris, what is the size boards you buy (length, width, height? And what are the dimensions of your stringers after you cut them to size?

Thank you for your comments and please pardon all the questions- John Carmichael

 

[John Carmichael]

Websites on Post & Ladder Open Stringer Roadbeds:
Here is the VERY informative article about a Columbus-area architect named Bill Logan who in 2002 began developing the construction method for I used for my raised HDPE flexible roadbed. I located the original online article that taught me about his “post and ladder” flexible roadbeds. It was a game-changer for me when I read it years ago. This brilliant innovator, Bill Logan was my mentor and unsung hero! Thank goodness I read this BEFORE I designed and built anything.

This 4 part article series is the best online information I can find on ladder stringer roadbeds. It describes inventor Paul Logan’s flexible stringer and post construction method. It’s often called the “Post & Ladder” method. This was the basis for my own railroad. I modified slightly Mr. Logan’s design and construction technique to improve strength, facilitate cutting, and allow a hidden place to run electrical lines:

Here it is!
https://familygardentrains.com/primer/roadbed/ladder1.htm
HDPE Flexible Roadbed Method - Part 2
HDPE Flexible Roadbed - Part 3

HDPE Flexible Roadbed - Part 4

In short, his revolutionary construction method involves the use of HDPE (high density polyethelyne) in what its inventor, Bill Logan, describes as an “open stringer”. He calls it the flexible post and stringer method. Mr Logan says “it still uses posts and stringers, but the finished installation looks far more "open" from above. In fact, the roadbed looks something like flexible "ladders" for which the "rails" and "rungs" are prepared in the shop and assembled to fit onsite.” Now, it’s often called a “Post & Ladder” Roadbed.

See the following video showing the great load bearing strength of one man’s post and ladder roadbed. Note the wide 4 to 6 ft. spacing of the support structures. The HDPE ladder roadbed between supports doesn’t even sag under the heavy weight train engine! Even so, a closer maximum spacing of 2 ft. would be much better. Also note the unsightly placement of the electrical conduit line tied to the bottom side of one of the stringers. A much better place to place the electrical lines is to hide them between the rails just under the ties in the small ¼” space above the stringer connector/spacer blocks in my design:

 

[dunnyrail]

Hi Dunnyrail:
Your statements raised more questions than answers for me. I admit I'm not familiar with Filcris. Please tell us more.
Questions:
My concern about using Filcris stringers in a flexible ladder roadbed is its lack of FLEXIBILITY IN CURVES. Do you use it where you have small curve radii? If so, what is the smallest curve radius you have? Also, how thick is one of your Filcris stringers.? My HDPVC has 3/4" thick stringers and the smallest radius I could make is about 4 ft. for my trolley line. (see roadbed photo below). Can your Filcris bend this tightly? When you buy the Filcris, what is the size boards you buy (length, width, height? And what are the dimensions of your stringers after you cut them to size?

Thank you for your comments and please pardon all the questions- John Carmichael

I have never used the Filcris ladder section but built a Garden Railway for a buddy using their Decking planks. Later we covered them with a product called ‘Eco Board’ that has much less issues with expansion. This stuff if a light colour and appears to be made from stranded plastic glued together rather than melted plastic that Filcris appears to be made of being a uniform Brown or Black colour. I am pretty sure that you would be able to get the curves to 4ft radius as some if the lines I have seen it on appeared to be a little smaller than this, perhaps users in the forum could comment re radius achievable.

Another option may be to look at the products used for Barge Boards on houses, this I have used for Concreteting sub-bases and does bend quite to small radius and has much less issues in expansion. There are quite thin and thicker options available UK, the thiner for the outside and the thicker for the cross beams to enable screws to be used. You would of course need to extensively cut things to get to the size you need, a bench saw used withncare and slowly ought to work and give the accuracy required. Again I have nit used it on my line being either wood ir concrete, bricks, paving slabs for my line.

 

[John Carmichael]

I beg your pardon as I must admit a big mistake. I'm not a chemist, I mix up chemical names- and I'm old. I told you incorrectly that I used HDPVC (High Density Polyvinyl Chloride), but it was actually HDPE (High Density Poly Ethelyene). I just plain forgot the name.

TrexTrim is the material I used. It is PVC lumber but is very similar in all ways to HDPE lumber. It’s very flexible, but I don’t know if it is more or less flexible than HDPE. I bought this size: SKU: WW010618B. This measures: 3.4” thick x 5.50” wide x 18 ft. long (actual). It’s white with wood grains. I had the supplier rip each board into 1.75” strips for the stringers. Wider boards are available but all will need ripping. The supplier delivered the ripped strips to my home for a small fee. Website: Trex trim brochure - Trex Inc. - PDF Catalogs | Documentation | Brochures

Please excuse me! I'll try to fix this mental typo error by editing my previous posts.

 

[John Carmichael]

HDPE (high-density polyethylene) roadbeds are made from very flexible high-density UV-treated PVC sold for house siding. UV-treated vinyl can also be used, but is less flexible. It’s available with faux wood grain and is ¾” thick. The lumber yard ripped many 18 ft. long 1 ½” wide strips for me. Two 18 ft. stringers screwed together back-to-back form a 18 ft. section of ladder roadbed by screwing 2 ¼” x 1 ¼” x 1 ¼”” composite wood spacers (we call them “brownies”) between the stringers every 6”. Its flexibility automatically forms perfect curves of the desired radii between any three points. Before joining with brownies, a single stringer can be bent into almost any curve, even tight R3 radii. After joining, both stringers become rigid and hold the desired shape. Stringers are connected end-to-end with 8” long pieces of HDPE screwed to abutting stringers. Position and join all stringers on the ground, then raise the entire joined roadbed little by little to the correct heights indicated by SCARM (a great track design app). Temporary vertical posts support it every 6 feet.

Now paint the roadbed. Sun eventually destroys plastics, even UV-protected ones. For extra protection and aesthetics, paint HDPE with primer and with two coats of desired color. After painting with Krylon flat dark brown spray paint for plastics, I removed the temporary vertical posts and replaced them with wood trestle bents using steel angle brackets. Then I bent the rails and attached the track. The roadbed is 3 ½” wide, matching LGB ties which are screwed to it. Use countersunk waterproof deck screws for the ladder brownies and joiners, and ¾” stainless steel tiny rounded screws for ties. Note: For strength, do not put stringer abutment joiners across from each other. Stagger them.

 

[John Carmichael]

Mine seems to work well

Hi Paul:
Would you please share a photo with us if you have one? I'd love to see what we're discussing. "A picture is worth 1000 words".

Thanks!

 

[John Carmichael]

I have never used the Filcris ladder section but built a Garden Railway for a buddy using their Decking planks. Later we covered them with a product called ‘Eco Board’ that has much less issues with expansion. This stuff if a light colour and appears to be made from stranded plastic glued together rather than melted plastic that Filcris appears to be made of being a uniform Brown or Black colour. I am pretty sure that you would be able to get the curves to 4ft radius as some if the lines I have seen it on appeared to be a little smaller than this, perhaps users in the forum could comment re radius achievable.

Another option may be to look at the products used for Barge Boards on houses, this I have used for Concreteting sub-bases and does bend quite to small radius and has much less issues in expansion. There are quite thin and thicker options available UK, the thiner for the outside and the thicker for the cross beams to enable screws to be used. You would of course need to extensively cut things to get to the size you need, a bench saw used withncare and slowly ought to work and give the accuracy required. Again I have nit used it on my line being either wood ir concrete, bricks, paving slabs for my line.

Hello Dunnyrail:
Could you possibly share a photograph of your roadbed so I can see what we are discussing? "A picture is worth 1000 words".

Thanks!