viaduct arches - what decides their shape and material?

[NittenDormer]

To be specific:

1) Why do some (but not all) stone viaducts have brick arches?

 

2) Why do some viaducts have semi circular arches, while others have a distinct 'corner' between arch and pier?

 

Also, does anyone know any good fairly low, urban, northern viaducts? Its all very well having Google, but if you don't know what to search for, its harder to find!

Thanks

[Mark Saunders]

I think a potential location you are looking for is Leeds heading out towards Holbeck on the Midland and even has a viaduct crossing it!

[JSModels]

The shape of the arch is determined by several factors, including (but not limited to):

 

The location and position of the bridge;

The loading that the arch has to transfer, and where it transfers that load to;

The height available.

 

For example, if a bridge has to cross a wide river, for example lets say 80 feet of span, but the track level is only 20 feet above the river, then (assuming it cannot have central piers) you can't have a semi-circular arch, as by definition if it's 80 feet across it would need to be 40 feet high. So it needs a shallower arch with the 'corners' you described.

 

A downside to this shallower arch is that more of the load is transferred outward rather than down, so the abutments at the sides have to be considerably larger to avoid them being pushed apart.

 

There's a lot more to it than that, but there's lots of info available online about bridge design if you want to research it. I might even find some links for you later if I have time.

 

JRB

[JSModels]

13 hours ago, NittenDormer said:

Also, does anyone know any good fairly low, urban, northern viaducts? Its all very well having Google, but if you don't know what to search for, its harder to find!

Thanks

 

Todmorden is a great example of what you're asking for:

 

 

Here's a model of it in 4mm that my late Dad built (with more than a little assistance from a teenage me) in the early nineties for the model of Todmorden station built by the now-defunct Todmorden Model Railway Society:

 

 

The viaduct had a plywood/timber structure, and the 'stonework' was made in sections, each cast in polyester resin from silicone moulds made from plasticard masters. The viaduct itself was around 8 feet long IIRC, and was built without any compression.

 

JRB

Edited December 21, 2019 by jrb
added screenshot of viaduct linked

[MR Chuffer]

Have you looked at the viaduct in central Burnley between The Barracks and Burnley Central, on the line to Colne?

 

And a beautiful one though not town-based but eminently model-able is the 48 span Whalley viaduct on the Blackburn Clitheroe line that even contains architectural features in some of the piers to blend in with the nearby North West Gate of Whalley Abbey.

[JSModels]

10 minutes ago, MR Chuffer said:

Have you looked at the viaduct in central Burnley between The Barracks and Burnley Central, on the line to Colne?

 

That would be This one:

 

 

The height is I think similar to the Tod one, but the piers are closer together, allowing use of a semi-circular arch (which, incidentally, are brick lined rather than stone).

 

JRB

Edited December 21, 2019 by jrb

[JSModels]

Or there's this one in Halifax which is an eliptical arch - a kind of half-way house between the semi-circular arch (Burnley) and segmented arch (Todmorden):

 

 

Incidentally, in the above image the large rectangular wall section to the right of the viaduct was the end of a second viaduct that carried the branch line to Halifax North Bridge Station & beyond, and would have crossed the view above just in front of the camera.

 

JRB

[34theletterbetweenB&D]

If something more modest is required, there's a little beauty in Cullingworth W. Yorks, just two miles East of Haworth, low, on a curve and practically over a crossroad with a pub. (The GNR branch that once ran to Ingrow, now on the K&WVR.)

[Alister_G]

Buxton in Derbyshire has 2 railway viaducts - just greedy I suppose...

 

 

 

 

and a trio of consecutive railway bridges:

 

 

Al

[chuffinghell]

9 minutes ago, Alister_G said:

Buxton in Derbyshire has 2 railway viaducts - just greedy I suppose...

 

 

 

 

and a trio of consecutive railway bridges:

 

 

Al

There is also a nice Italian restaurant in Buxton called St. Moritz