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Hello all,

Part of my N scale layout is going to feature an Austrian bridge (based on the Pfaffenberg-Zwenbergbrücke) which is similar in size to this giant bridge that I came across on Jernhesten (highly recommended for Swiss modellers but written in Danish). I would estimate the bridge span at 14 coach lengths which at 1:160 scale is about 16.5 cm x 14 = 2.31 m!!


Picture from Jernhesten

I have begun to design a bridge in Google SketchUp 6 (available free), although my bridge will have to be a bit smaller:

Picture from Eurofima Prima!

But I wonder what is the best method of constructing the main span? By gradually bending plywood using water etc. or by using flexible plastic sheets or plasticard? It will be quite an engineering challenge...has anyone attempted such a scratch build? I would ask Jernhesten but my Danish is rather non-existent. Any advice would be most welcome...

And for those who doubt such bridges do actually exist:

SBB Locomotive 460 093-8 with IC 835 Brig-Romanshorn
Bigger picture available here

Goedel
 

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QUOTE But I wonder what is the best method of constructing the main span? By gradually bending plywood using water etc. or by using flexible plastic sheets or plasticard? It will be quite an engineering challenge...has anyone attempted such a scratch build? I would ask Jernhesten but my Danish is rather non-existent. Any advice would be most welcome...

I think I would attempt to build the central arch around a former. You could use Masonite (hardboard strips) these are very pliable and then build it up using the vertical sections to help retain the arch. In effect it would be an assembly jig.
 

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QUOTE I would ask Jernhesten but my Danish is rather non-existent

You should ask in English anyway. Many Danes have good English. I was in Denmark for an international scout camp way back in 1972. We had hospitality with a Danish scout and his family for a week beforehand. I remember watching a US film on Danish TV which had Danish subtitles, i.e. it wasn't dubbed. I don't think this was unusual, which explains the high anglo phone ability of this small nation.

Meanwhile here's a model of the "Landwasser viaduct"; reputed to be the world's most photographed:-

Bridge Plant Landmark Aqueduct Formation

The model can be seen at Modellbahntreff which is located next to Interlaken West railway station. I think the scale is O gauge or larger, so you can imagine just how big this model really is. Those ceiling hangings are probably one metre on the long dimension.

I hope to have my own photo of the real thing by the end of the summer
. I hope I need those sunglasses!

David
 

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QUOTE (Makemineadouble @ 8 Jul 2007, 18:35) <{POST_SNAPBACK}>I think I would attempt to build the central arch around a former. You could use Masonite (hardboard strips) these are very pliable and then build it up using the vertical sections to help retain the arch. In effect it would be an assembly jig.


I agree with MMaD's idea.
For the vertical sections and track bed I would use Supawood (MDF) as it is stable and it can be shaped, formed and glued as you would solid wood and it is easy to paint. I am in the planning stages of my layout and have been considering several options for a removable "duck under".
I think a bridge like this will actually work very well for that purpose and it can be custom made to fit the available space.

Like Goedel said, it will be quite a model engineering challenge. But then again us modellers thrive on modelling challenges. I will be watching this post with interest.

Kind regards


Johan
 

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I'm not aware of the product mentioned by MMaD and Johan so I can't comment on that, but I do have a lot of experience in building wooden boats (models) so I would employ some of the skills I have from that area.

I would use very thin ply 3mm -4mm, soak it to enable it to flex and then shape on a former to the required radius. Once dry aand set in the required shape add the second layer by gluing it with PVA glue and pin it into place(using small nails for finescale woodworking available from model shops who sell model boat kits). I would add several layers of this glued and pinned together until I had acheived the scale thickness of the main arch. Once the glue sets you can remove the pins. This should be strong enough for your vertical struts to be added to.
 
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