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RhB Landwasser Viaduct in HOm (3.5mm/foot) ?


Talbotjohn
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Well, on balance I’d say that constructing straight arches, even with a 20% gradient, plus wedge-shaped piers, would be more straightforward than scratchbuilding curved arches with rectangular piers.

Modelling in HOm, I won’t be building a scale replica of Landwasser, but I will need to build a smaller curved viaduct. It’s a pity that all the kits I’ve seen (which are quite good in themselves) are on pretty tight radii. 
Just toying with ideas at this stage. Has anyone tried carving a curved viaduct out of dense foam or balsa wood?

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52 minutes ago, Samedan said:

Has anyone tried carving a curved viaduct out of dense foam or balsa wood?

This ones my test piece although the arches are too compact it proved the theory. 
0CCB96C6-FB6D-4C89-A503-104A39C90511.jpeg.e5cf9ff9843b57f0d3f7b614540414d0.jpeg

 

More here,

 

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37 minutes ago, grow45 said:

Just in case it is of use here is another drawing from a book published by Bemo.

 

IMG_20210710_163315.jpg

Hmm like several of their stock drawings they’ve got the arch dimensions wrong though. 
As the RhB used the Hennings drawings in their UNESCO documents I’d hope they are the accurate ones ;) 

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29 minutes ago, PaulRhB said:

Hmm like several of their stock drawings they’ve got the arch dimensions wrong though. 
As the RhB used the Hennings drawings in their UNESCO documents I’d hope they are the accurate ones ;) 

You can never be 100% certain of architects drawings, or in builders ability to interpret them. I once had a very angry architect call me up to tell me the steel staircase for his building had arrived (that I had drawn) and it didn't fit in the stairwell. Turns out that the builder had ignored the instructions that said "build wall to underside of half landing" and had instead built the wall all the way up two stories high before the staircase was craned in, last I heard the Architect was planning on using the builders head to demolish the wall LOL. Even after construction surveys can be wrong, surveyor sees 5 arches that look the same and decides to measure one accurately, measure the total span and average everything out afterwards.

 

Also never scale off a drawing only follow dimensions, I worked on a set of QE2 drawings that had been left in a drawer for years, if you had scaled off the drawing the ship would have been about 2ft wider on one side of the centre line compared to the other, drawers can be exposed to heat and damp and drawings especially paper ones distort.

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2 hours ago, Samedan said:

Well, on balance I’d say that constructing straight arches, even with a 20% gradient, plus wedge-shaped piers, would be more straightforward than scratchbuilding curved arches with rectangular piers.

More straightforward and more correct. Curved arches would have unsupported bits on the inner sides and outer top. These would fall down, leaving you with straight arches.

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2 hours ago, DGO said:
3 hours ago, PaulRhB said:

 

You can never be 100% certain of architects drawings, or in builders ability to interpret them

No I agree but the Schweers & Wall books are rather notorious for being inaccurate in the RhB modelling community. For stock the Claude Jeanmarie books are considered the definitive guide and the Henning drawings were used by the RhB in the UNESCO application for the Albula and are on the info boards if you walk the pass too ;) 

If I was to put money on it the latter two sources would be where I’d go for reference. 

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20 hours ago, PaulRhB said:

Hmm like several of their stock drawings they’ve got the arch dimensions wrong though. 
As the RhB used the Hennings drawings in their UNESCO documents I’d hope they are the accurate ones ;) 

Looks like a site visit with a very long tape measure is needed.

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33 minutes ago, grow45 said:

Looks like a site visit with a very long tape measure is needed.

Don’t you just hate the idea :lol:

 

I’ve got a laser measure that can do 100m but you’d need to work it all by trigonometry as the arches are 60m up. 

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Yes the Solis viaduct is also in the book. I’m currently trying to find someone with a flatbed large scanner as the folio style means the book won’t go through the local shops scanner rolls. The other alternative is to set up a camera stand. 

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On 10/07/2021 at 18:29, Jim Easterbrook said:

More straightforward and more correct. Curved arches would have unsupported bits on the inner sides and outer top. These would fall down, leaving you with straight arches.

Try telling that to Messrs Faller, Kibri, Noch etc! Your reply amused me. I googled a few articles, forum threads etc on building “curved” viaducts. It’s amazing the lengths people go to to get the underside of curved, tapering arches to fit. Of course, real viaducts on a curve are very gentle curves and so the straight arched are not as obvious. 

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Great thread this, I knew the piers were wedge shaped from front to back but didnt realise that the arches were straight, although I have written that down in my notes. Sorry if Ive missed this but any idea how wide the arches are (not the span but the width) I once drew the bridge on a piece of card in NM scale and worked out that it was 433mm high and 906mm long with a radius of 666mm (although I think track radius tightnes across the bridge) The arch span is 133mm.

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36 minutes ago, Nutbrook said:

Great thread this, I knew the piers were wedge shaped from front to back but didnt realise that the arches were straight, although I have written that down in my notes. Sorry if Ive missed this but any idea how wide the arches are (not the span but the width) I once drew the bridge on a piece of card in NM scale and worked out that it was 433mm high and 906mm long with a radius of 666mm (although I think track radius tightnes across the bridge) The arch span is 133mm.


This is a cross section of pier 4 

C4E37196-4CB3-4DCA-A2C4-BD6D8D90BF62.jpeg.8fce1347ed73bebc0be47c292500473f.jpeg

 

Looking back at the S+W drawing I see where they’ve got the dimension error from. 
The pier centres are at 23.5m so the top of each pier is 3.5m with a span of 20m so the wedge appears to have confused them. 
3131FB28-9FE0-469D-A5A4-0839624AF9D5.jpeg.b6f269e21bcba0161b57954897d67034.jpeg8D7BBBE9-B12A-4114-B412-FB71C4B14340.jpeg.a56f92a1ca60ceb71f50daad010a2662.jpeg

 

 

Edited by PaulRhB
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50 minutes ago, Nutbrook said:

Great thread this, I knew the piers were wedge shaped from front to back but didnt realise that the arches were straight, although I have written that down in my notes. Sorry if Ive missed this but any idea how wide the arches are (not the span but the width) I once drew the bridge on a piece of card in NM scale and worked out that it was 433mm high and 906mm long with a radius of 666mm (although I think track radius tightnes across the bridge) The arch span is 133mm.


This is a cross section of pier 4 

C4E37196-4CB3-4DCA-A2C4-BD6D8D90BF62.jpeg.8fce1347ed73bebc0be47c292500473f.jpeg

 

Looking back at the S+W drawing I see where they’ve got the dimension error from. 
the pier centres are at 23m so the top of each pier is 3m with a span of 20m

 

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Its also interesting that the top of the piers last measurements are 1.20m on one side and 1.34 on the other possibley for the cant of the rails on the bend or for drainage on the deck, or both

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Yep it’s the cant, the drainage was through the stepped area outlined which was full of ballast. 

4B6F94EA-D909-4A91-B935-2C1830C189C9.jpeg.5994aaadbbf824bede704fa03c324147.jpeg
 

and through the drains 

42E985AB-9971-4C6E-AC2F-23C7E6C68F50.jpeg.458625ad146a929fe058b9d728443be9.jpeg
 

As part of the refurbishment about ten years ago it got a new deck and drainage system. 

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