Stone Arch Viaduct / Bridge

[railandsail]

Here is an idea just offered,

Check out some of the products by Chooch Enterprises. I think that they might be of use to you.

https://www.choochenterprises.com/HOwalls.html

I just sent them an email asking:
I wonder how thick those flexible walls are?

And I wonder how I would fashion the ring of stones that form the arch openings,.....and those proud 'columns' that stretch vertically down each footing??


There is also the possibility that these 'Chooch wall materials' could be used to make molds for casting?

[railandsail]

Yesterday evening I experimented with making the arches all identical rather than 2 sizes (with the exception of that one single one over track coming thru the back wall).



 
I think it looks presentable, but I do have a question about the very lower portion where the footings are getting to be quite a bit 'wider' compared to the others ?.....opinions??



BTW, in constructing this mock-up I had to place each 6" wide arch drawing at different heights to the adjacency ones,...and even more exaggerated so in this particular higher grade slope (about 4%). I imagine this means I would have to do the same offset of each 6" piece whether I was constructing this 'wall of arches' with a casting method, or a decorative flexible facing material ??

[Charlie B]

Just keep in mind there would have to be a legitimate reason for an arch, or for that matter a bridge, over anything, otherwise the road would be built on a fill.  Many old rail lines would use wooden trestles to build a line and then cover them with fill. 
Charlie

[ngauger]

Charlie's correct in this.

If there is no legitimate reason to "Build" an arch, the standard construction company would build the road on a fill dirt hill.
Then place a retaining wall across the front of the dirt or use the first arch support/wall as the retainer, Then begin the viaduct from there.

The picture on this page shows the PRR/Reading viaduct near me. It starts right at the hill in the background.
https://en.wikipedia.org/wiki/Philadelph...er_Viaduct

[railandsail]

I figured I was going to have to stop making arches as I got lower and lower to 'ground level', but sort of wondering where that might be?

It has been suggested that I could make use of that Chooch flexible stone wall material to form the decorative facings of my viaduct structure,...and i liked the idea. BUT at $12.99 per each piece (3.5" x 6") that could become pretty expensive.

[doctorwayne]

.....It has been suggested that I could make use of that Chooch flexible stone wall material to form the decorative facings of my viaduct structure,...and i liked the idea. BUT at $12.99 per each piece (3.5" x 6") that could become pretty expensive.

For the price of perhaps 3 or 4 of those Chooch sheets, you could buy a 4'x8' sheet of .060" styrene, and, if you don't mind making it a concrete bridge rather than a stone one, make the face of the arches as a single piece.  I'd probably use .020" sheet styrene to do the arches, as the .060" stuff won't curve sharply enough.  

You'd also have lots of material left over to build all sorts of stuff.  I use it for the unseen side of kitbashed structures, and cut into strips, it's great to use as bracing inside of large structures.  I've gone through at least four or five sheets.













The retaining wall visible in the photo below (which extends pretty-well right through this town, mostly hidden by structures) was also scratchbuilt using .060" sheet material...







This one makes use of a bunch of Walthers window castings I had left after building the Languay factory, shown in the second photo.  The rest of it was scratchbuilt using .060" sheet styrene.







All of my many paper background structures are on the same material, too...





I agree with Charlie and Mikey, though....the approaches to the viaduct would be on fill at least to a height that would be practical.  It would have been a lot cheaper than using stone or concrete for the whole thing.  I'd think that the lowest arch that would look appropriate should be at least high enough for a vehicle to drive under it, even if you don't need a road at that particular spot.


Wayne

[railandsail]

So a lot of the brick facings on your buildings are printed paper glued onto the sheet styrene?

[doctorwayne]

So a lot of the brick facings on your buildings are printed paper glued onto the sheet styrene?

The first of the last two in my post, above, is, and there are quite a few of them on the layout.  Some are simply two dimensional "flats", while many have some depth, like this one (ignore the curve at the eaves - imparted by the camera's lense)...





This one has some short side walls, too, but looks only so-so in this view...



...and less-so here...



...and this one pretty-much finishes it off...



These two have about an inch of side wall depth , but there'll eventually be three-dimensional structures in the foreground...



These two are basically "flats", with their depth only that of the .060" sheet on which they're mounted, plus  the 1/8"x1/8" stiffeners cemented to the back....





Unfortunately, those background structures are no longer available.

But, to answer the un-asked portion of your question above - yes, if your viaduct isn't going to be right up front to viewers, then you can likely do a very convincing stone "veneer" using printed paper.

For the first batches of those flats, I used contact cement to affix the paper to the styrene (it helps to first "prep" the styrene with some brushed-on solvent - I used MEK, which I also use as a cement for styrene.  Such prepping makes applying the gelled contact cement easier, and gives a better bond because the styrene otherwise draws too much of the solvent out of the contact cement, making it difficult to spread.  (I use a 2" brush for this work.) 
The back of the paper also requires a coat of contact cement, and you need to let it dry the for at least the amount of time noted on the can. 
To get good alignment of the paper on the styrene backing, lay a sheet of waxed paper over the dried cement on the styrene, then place the paper atop it.  Jockey the paper around as needed, then move the waxed paper slightly so that a sliver of the bottom and one side of the styrene are exposed.  Next, align the paper with both of the respective exposed edges of the styrene and very carefully press down to secure the paper in alignment with the backing. 
You can then begin to slide the waxed paper from between the two surfaces, following along with your free hand to smooth the paper onto the styrene.

Later, I experimented by using the same 2" brush to apply a liberal amount of MEK (it evapourates rather quickly) to the styrene, then simply placed the paper atop it while the MEK is still wet, smoothing it from the application side and across the full width. 
While this can be quicker than the contact cement method, you need to work while the MEK is still wet, but not pooled - too much MEK can soak through the paper and mar the printed image.  Also, you can't use the waxed paper method for protection while you align things. 
While I generally had good results, I also did some where the sheet of styrene backing was cut only to a rough size, allowing the paper image to be placed within its edges, then used a utility knife to trim the backing to-size.  Images that don't have sidewalls of any appreciable depth (the thickness of the backing and its associated bracing) should be painted a suitable colour that won't attract the eye of viewers.

Wayne

[railandsail]

Then here comes another suggestion that looks VERY promising?

If you are thinking of building this up from castings, consider Bragdon foam.  The castings are light, unlike most casting material, and can easily be cut with scissors.  Using the foam material and their high quality molds will produce superior rock walls and faces.

www.bragdonent.com

https://www.youtube.com/watch?v=BziZjHSf...ziZjHSf2LA

Have you ever worked with this material doctorwayne?

[BR60103]

One of the Platelayers built a rather large viaduct using hydrocal castings. I think he spent a couple of years on it.

A long presentation on the construction   https://torontoprototypemodellers.files....uction.pdf

This is the opening ceremony    https://www.youtube.com/watch?v=8Z7MsVcv...e=youtu.be

This is a bit bigger than the one you want.

[doctorwayne]

.....Have you ever worked with this material doctorwayne?

No, I wasn't even aware of it, but it looks like it would be useful for some projects.  I do think the relief is a bit too exaggerated for my tastes though, at least for a stone bridge.

Of course, while searching for suitable photos of stone bridge supports, this is the first one that popped-up...




...while these were the ones I was seeking...
















Wayne

[railandsail]

Here is an article about making molds and building a stone arch bridge. http://www.gatewaynmra.org/2010/casting-...h-viaduct/

I recall seeing this one before, but I just reread it. I like the idea of the individual arch molds, but think I want to make my separation down the columns rather than in the center of the arch. Then my separate 'proud column pieces' would cover that seam.

I also like the idea of supporting the mold with sand (or whatever), as then I could make a few of those arches that need to be curved?

I'm not particularly excited about the thickness of his arch pieces. Can they be made thinner?...with reinforcement materials?,...particularly if they are just going to be 'decorative facings' placed on PVC foamboard substructure? (I wonder why he needed such thick castings on those robust wood framing??

[railandsail]

Building with Molding/Casting Products



If I were to build with molding/casting type products, I think I could do it with 3 molds?

1) Mold #1.   The curved interior arch roof surface. Question would be if this could be a pre-curved mold, or if it needs to be filled with plaster/hydrocal while in a flat stage, then bent into curved shape prior to total hardening??

2) Mold #2.    For each identical arch section, 6" wide from c to c of arch columns, the flat surfaces of the faces, including those 'lip' of stones that rim the arch opening.

3) Mold #3.   A separate mold for those vertical columns that would glue on over the joints in the multiple arch moldings.

[cn nutbar]

I've been following this very interesting thread and even though I cannot add any technical suggestions I thought this picture might be useful---BTW,great work and contributions everyone

   

[railandsail]

Here is a really nice presentation of building the specific B&O viaduct.

http://basrr.blogspot.com/2013/01/mold-m...aduct.html

Two very interesting things;
a) the manner he included that vertical proud column in with the front facing mold,
b) casting of the curved arch roof