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So as you’ll see in the link bottom of my signature, I’m embarking on Barnstaple Town’ish!

The curved steel/cast viaduct is quite a feature I would like to represent.

Seen Here.

 

post-32910-0-81939300-1546551280_thumb.jpeg

This video shows it well.

 

So I’ve found this https://www.track-shack.com/acatalog/Wills-SS57-OO-Scale-Vari-Girder-Plate-Girder-Panels-Plastic-Kit-Wills-SS57.html

WILLS SS57 OO SCALE VARI-GIRDER PLATE GIRDER PANELS - PLASTIC KIT

I’m wondering if it’s worth trying to bend it heat? Gently or slot Vee cuts out. There is what looks like a 1.1/2 width panel on each span but a dremel can soon sort that out.

Or do the viewers think just get some plastikard and crack on.

Now rivets! Are Archers the best bet? 2 lovely lines of them along the top as seen in the video.

The main track bed will be 3.6mm ply and probably wood dowel for the columns. Are they 2ft diameter anyone know?

All comments greatfully received.

Cheers

Ade

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The Girders aren't curved, they are straight, and spaced at angles to each other to get the curve. Look at the photo and you will see this also corresponds with the piers.

 

Andy G

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The Girders aren't curved, they are straight, and spaced at angles to each other to get the curve. Look at the photo and you will see this also corresponds with the piers.

 

Andy G

 

Really? That's what I would have thought - but the video still suggests otherwise.

 

Regards,

John Isherwood.

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Really? That's what I would have thought - but the video still suggests otherwise.

 

Regards,

John Isherwood.

 

It is difficult to determine in the video. The top plates are certainly curved. I would have expected the plate girders themselves to be straight, as Andy G has suggested, but in the video, they do look to be quite short and curved. That may be true, or it may also be a trick of the camera angle.

 

In my opinion, and using that video and all the photos I can find, the jury is still out on whether they are straight or curved. :)

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It is difficult to determine in the video. The top plates are certainly curved. I would have expected the plate girders themselves to be straight, as Andy G has suggested, but in the video, they do look to be quite short and curved. That may be true, or it may also be a trick of the camera angle.

 

In my opinion, and using that video and all the photos I can find, the jury is still out on whether they are straight or curved. :)

From an engineering practice point of view I would expect the bridge to be made up of short straight girders.  And early in the viaduct section of the video I think this can be discerned.  On page 101 of 'The North Devon Line' / Nicholas & Reeve / Irwell 2010 is a photo where the effect is very subtle but close inspection shows straight girder sections.

 

Chris KT

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That fits better with what we would expect, Chris.

Incidentally, for anyone using the Wills vari-girder, each section is a separate piece, so it would be relatively easy to build it with a light angle between each piece to create a similar 'curve'.

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The Wills kit is a nice product but the sections look too short for that bridge.

I would happily accept this compromise because the alternatives are to scratch build them from plastikard or 3d print.

If you plate both inside & outside, then a little filing on the inside plates should be enough to help it bend, but the riveted top may require a different approach.

Why not just get on & try it? You will probably think of a solution as you build it.

 

Try to visualise the columns in relation to the track gauge, which as we know is 4'8½". It may be worth making 1 up & deciding if it looks right.

If you can't get the right size of wood dowels, you could try brass or plastruct tubes.

 

Good luck with building it. It will make a nice feature on the layout.

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That video is great. As per the other I was expecting to say the girders were straight, but I agree that if they are, they dont look it. It may be an optical illusion, or it may be that the top (and bottom plates are actually curved and the vertical section is shortish flat sections

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I have watched the video a couple of times, both on the computer screen and my 42 inch telly and it definitely looks like short straight sections of girder, each section slightly off set from the previous one, the butt plate joining the two section, slightly off set between the two. I paused the video a couple of time to double check it.

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Thanks for all the great replies, but as Pete The Elaner says probably best to have a crack at it and see how it goes.

But telling if its curved or not I think as Snooper says its short sections slightly off set.

three more pic's to add to the debate!

On the people on the viaduct one you can see the rail bulks are in straight sections compared to the curve of the steel. 

The other two the bottom one the section beyond the handrail does look curved in sections looking at the bottom edge against the river.

Photo Credits I think to the Cornwall Railway Society I'll have to check when I get home.

 

post-32910-0-63720500-1546593742_thumb.jpgpost-32910-0-61278000-1546593788_thumb.pngpost-32910-0-38549700-1546593825_thumb.png

 

 

Until next time 

Cheers.

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The Wills kit is a nice product but the sections look too short for that bridge.

I would happily accept this compromise because the alternatives are to scratch build them from plastikard or 3d print.

If you plate both inside & outside, then a little filing on the inside plates should be enough to help it bend, but the riveted top may require a different approach.

Why not just get on & try it? You will probably think of a solution as you build it.

 

Try to visualise the columns in relation to the track gauge, which as we know is 4'8½". It may be worth making 1 up & deciding if it looks right.

If you can't get the right size of wood dowels, you could try brass or plastruct tubes.

 

Good luck with building it. It will make a nice feature on the layout.

Regarding the 'shortness' of the Wills girders. Surely it depends on what radius the OP intends to build it to? If the model is going to have tighter curves than the prototype, then it might work out well as is.

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Try building a bridge from foam board and or card to see how it looks.

 

You could experiment with curved and straight sections.

Does the local museum have any information, failing that a request to the National Railway Museum may reveal some information.

What does the bridge look like on the 25" OS map for that area?

 

Does anyone know who built the bridge sections?

If so a search of their archives?

 

Gordon A

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A card mock-up is a great idea. I did that for the station building on my layout. It was really quick to put together and helped to get the dimensions correct when building the proper plastic version.

I don't know why I forgot to mention it.

 

I must finish it one day....  :scratchhead:

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On the photo with the spamcan there is a definite angle in the girder above the pier (just ahead of the cab).  Also the bottom of the openings between the "spokes" of all three driving wheels coincide exactly with the top of the girder.  This strongly suggests the girders are straight between piers - which is what is to be expected structurally, as a curved girder would have forces tending to twist or overturn it so would have to be considerably stronger than a straight girder with the same load. 

 

Given that this photo strongly indicates the girders are straight, I suggest that the slight curve that appears to be there in the other photos is either an optical illusion or something to do with the camera lens.  Might be worth printing up one of those really big and putting a ruler on it? 

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On the photo with the spamcan there is a definite angle in the girder above the pier (just ahead of the cab). Also the bottom of the openings between the "spokes" of all three driving wheels coincide exactly with the top of the girder. This strongly suggests the girders are straight between piers - which is what is to be expected structurally, as a curved girder would have forces tending to twist or overturn it so would have to be considerably stronger than a straight girder with the same load.

 

Given that this photo strongly indicates the girders are straight, I suggest that the slight curve that appears to be there in the other photos is either an optical illusion or something to do with the camera lens. Might be worth printing up one of those really big and putting a ruler on it?

 

I understand from a friend that the local museum in Barnstable has some aerial pictures of the bridge.

 

Gordon A

Thanks Edwin I hear what your saying but! I love a but don’t you I’ve found a photo of its demolition in 1977 or 78. Shows it well and I know a camera can skew things but a straight edge on the photo blown up shows it curved via short sections angled a bit to the next one.

As for the aerial shots thanks Gordon I’ve found a dozen I expect myself but great info. Thanks.

 

 

 

All for the melting pot.

Until next time

Cheerspost-32910-0-13577100-1546652140_thumb.pngpost-32910-0-17917500-1546652241_thumb.pngpost-32910-0-64345200-1546652274_thumb.pngpost-32910-0-05572900-1546652306_thumb.jpegpost-32910-0-41447300-1546652320_thumb.jpeg

 

Edit to put photos back in.

Edited by AdeMoore
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Normal construction method for a girder bridge on a curve would be a series of straight girders between each pier/pillar.

 

But this one seems to be an exception where each span has been made up with a series of small (4'?) plates to form a curved girder. Given the very tight curve, building it the usual way, it would have needed it to be much wider.

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Normal construction method for a girder bridge on a curve would be a series of straight girders between each pier/pillar.

 

But this one seems to be an exception where each span has been made up with a series of small (4'?) plates to form a curved girder. Given the very tight curve, building it the usual way, it would have needed it to be much wider.

Cheers Joseph I believe you could well be right.

I’m gonna get a couple of packs of the Wills product ordered up, then see the viability of that route.

I’m planning on in my head 4th radius curve 572mm. Yet to put template to paper.

Cheers

Ade

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Thanks for all the great replies, but as Pete The Elaner says probably best to have a crack at it and see how it goes.

But telling if its curved or not I think as Snooper says its short sections slightly off set.

three more pic's to add to the debate!

On the people on the viaduct one you can see the rail bulks are in straight sections compared to the curve of the steel. 

The other two the bottom one the section beyond the handrail does look curved in sections looking at the bottom edge against the river.

Photo Credits I think to the Cornwall Railway Society I'll have to check when I get home.

 

attachicon.gifIMG_2787.JPGattachicon.gifIMG_3670.PNGattachicon.gifIMG_3671.PNG

 

 

Until next time 

Cheers.

Ah, but in the top photo, the longitudinal timbers that bear the rails are much longer than the pipe sections which are longer than the girder sections. Even the pipe looks curved, but who in their right mind would manufacture a curved pipe? So the pipe sections have to be straight, but the whole pipe looks curved, similarly the bridge girders are short straight sections.

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  • 2 weeks later...

Cheers Joseph I believe you could well be right.

I’m gonna get a couple of packs of the Wills product ordered up, then see the viability of that route.

I’m planning on in my head 4th radius curve 572mm. Yet to put template to paper.

Cheers

Ade

Be interested to see your findings on the viability of using the kit. With a curved bridge, albeit with angled joints to straight sections, the inner and outer ‘radii’ straight sections would need to be of differing lengths to achieve the curve?

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Be interested to see your findings on the viability of using the kit. With a curved bridge, albeit with angled joints to straight sections, the inner and outer ‘radii’ straight sections would need to be of differing lengths to achieve the curve?

Cheers Fairburn, I’ll be finishing the signal box and station first.

What you say about the shorter and longer sides I had not thought of, so thanks for the heads up on that. I think you are right on that.

Cheers

Ade

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