curved stone viaduct


Maxitrains

Maxitrains

Member
OK, so here is my thread about the curved stone viaduct which I need for the upper rail, over the river and lower dockside line. I'm building this in carton, I hope it works, I made a sort of mould to hold the layers of carton while the glue dries up, holding them in the curve I want them, then once dry I drew up what the arches had to look lke and started cutting up the shape. After that I have to apply mosr glue to it, so it solidifies and will be a robust structure. After that I will start coating in plaster to give more body and could be able to sculpture the bricks, or else I can print some brick paper and apply on it, but sculpturing has a more dramatic effect. Here are some photos of the process.

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That is a really cool idea for making a viaduct. I look forward to seeing it with the plaster on it. Nice work!
 
Very ingenious idea, Maxi. After seeing what you did with the styrofoam warehouse, I think you can do almost anything with stuff most of us would wreck. :)
 
You are quite the resourceful modeler. It's nice to see how somebody has a need for an item and then creates it. Good for you! I'll enjoy following this thread.
 
Thanks for all your wonderful comments. I am a guy that tries everything before going to the last choice ( i.e. Ready made items ), sometimes I cannot do otherwise since the details would be too much time consuming to recreate, but I always tried anything, sometimes though I started things which I never finished, maybe because in some detail I lack from thinking. fo example, the foam warehouse which I was doing, I simply stopped working on it, cause I cannot get any ideas on how I should make the windows, initially I thought I would print a window ( square frames ) on transparent sheets, and then stick them to thin frames of wood, but that didn't work cause the transparent print was indeed transparent and couldn't get that wooden frame effect, and now its there standing at a still, waiting for the right idea to come up.

But there are other times where I finish up my jobs, something like the wooder trestle bridge I made some years ago or the other stone bridge which I made as an initial trial.

Now since I don't have any plans for such bridge as the above, I made all in my mind and looking on some photos found on internet, but I still lack from the bridge width, which I still think I made it narrow, the width is 8mm - Rail - 8mm ( HO scale ), so if anyone has some good photos or some plans, I would be greatful if he could pass me some information before I proceed on this project.

Thanks
 
Maxi. I'm not quite sure where you're measuring from but the absolute minimum clearance should be 3.5 mm measured from the center of the track. So that means you need to have 7 mm plus the width of the track. This does not count the additional clearance you need because the bridge is on a curve, which is about .5 mm for each degree of curvature. Just from your pictures, it appears the end of the ties will be right up against the side of the viaduct. This is not enough clearance.

I couldn't find a good picture of a single track viaduct but here's one of a very old stone viaduct still carrying traffic in Canton. Mass.

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If you just eyeball the clearance and follow it on your own viaduct, you should have it right. You can see there's enough room for a walkway and a fence on the side of the viaduct. There have been narrower viaducts built but, with the exception of very small narrow gauge viaducts, the engine was never close enough to the edge the he could lean out of the window and look down the side of the viaduct. That kind of thing made engineers nervous. :)
 
Great idea Maxi. I ended up making a major change to my viaduct yesterday. Some times changes need to be made. I hope you finish this one. I'm interested in how it will turn out.

NYC_George
 
Looks close, Maxi, but you are going to have to watch the clearance as the viaduct curves. One thing you can't have is any part of the train swinging out and overhanging the viaduct. Railroads were careful to provide enough clearance that any dragging equipment or wide loads wouldn't derail the train and send it plunging off the viaduct. I'd get some flex track and tack it down to the viaduct as you build it to make sure you're maintaining enough clearance. Some kind of barrier, like a concrete berm or heavy steel fencing, was also common at the top of the viaduct.
 
Oki, now I checked the height in place and had to cut some of the pier height to fit in place, I made it taller just in case (you can cut from a long piece, but its harder to join a short piece and had it steady :) ). I sanded a little the sides and fitted it in place exactly. I took the moment to snap some photos which will be displayed here under, and soon after that I took it off again and applied white glu on it to solidify the layers, after it dries up, I will decide with what to cover it, either plaster or clay ( which gives you more tie to work on, and can build up a thick layer to widen it a little, and its also good to model it while still soft. If any of you guys have any other idea with which I can cover it, I would like to hear the idea/s.

Thanks

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Looks good, Maxi. I think I'd avoid regular plaster, since there's a lot of water in it and I'm afraid it would end up warping the bridge. I don't know what it would be called in Malta but we have a product called patching plaster here. It's already mixed up in small tubs. It's mostly clay with a lot less water than regular plaster. You can apply several thin coats until you get the coverage you want. It's carvable and sandable and doesn't crack. I've used it before on wood structurs without ay warping problems.
 
I decided to start covering the bridge in clay, since clay is more workable and also resistant after it dries, and so far when applying it, I was achiving a very good result, its very workable and very smooth.

To my surprise the following morning, when it started to dry up, on parts where I applied a thick layer of clay, some small cracks appeared, but where I applied thin layers on a smooth surface, it cracked like the earth in a desert, cracked in patches and lifted up, I guess this happened since the clay dried from the outside, but on the carton side it was still moist, and so the wet surface remains expanded more then the dry one, resulting in upward curved cracked surface.

something like this
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I will now try to ticken the layer on the side where it cracked heavily, maybe I can fix it, the side where small cracks appeared, I will leave till when I will apply the final thin layer for detailing, since clay will give me time to apply piece by piece and do the detail at the same time.
 
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Heck, Maxi, if it really looks like that, just weather it with some india ink washes and you should have pretty good looking stone viaduct. :)
 
Just wondering Maxi if you might have a problem in the furture with the clay falling off after it totally drys ?
 
Interesting problem! I think you just happened upon a neat way to make dry river/lake beds...
 
OK here's my update so far on my curved bridge, after letting it drying up from the layers of glue, I gave it another coat of white glue to harden the cardboard, and sprinkled some beach sand on, to give is some grip when I started to cover with clay.

On my first trial I was so happy, because the clay looks so smooth and nice while applying!!!, then my nightmare, when it dried up I found this:

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and on the other side it was worse because the layer I applied was thinner. Then I sanded up the front part till I leveled it smoothly adn applied again some patching clay, left it drying, sanded it again and re-applied some more clay, and so far on the front side I have this result, not yet satisfying but getting there.

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I hope it doesn't get too heavy till I finish it :) so far I'm still working on teh other side which I had to start allover again since I had a thin layer and almost nothing to sand down.
 
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