Curved bridge

On Nov 29, 11:39 am, "Just zis Guy, you know?"


Mould your own masonry sections. Various resources on the web and in book. One method is to make a tray from a thin flat lego base (the ones that are slightly flexible) with a lip of bricks around it. Add a layer of plasticene and impress your masonry pattern into it. Pour in plaster of paris, incorporating some strengthening if neccessary. The beauty is you can dis-assemble the lego mould to get the cast piece out easily.
MBQ
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 30 Nov 2009 05:42:10 -0800 (PST), " snipped-for-privacy@hotmail.com"

Good ideas, but I am building in brick. Guy
--
http://www.chapmancentral.co.uk /
The usenet price promise: all opinions offered in newsgroups are guaranteed
  Click to see the full signature.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Nov 30, 10:48 pm, "Just zis Guy, you know?"

Masonry, brick, same technique applies.
MBQ
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 28 Nov 2009 03:12:43 +1300, Graham Harrison

It is possible to find curved model bridges, eg Kibri, Faller, old Tri-ang etc.
Prototypically, a span can't be curved, because the center would be outside the supporting points at the ends and would roll over. The prototype gets over that problem in several different ways that I am aware of: - very short straight spans. - wider straight spans so that the track can curve from inside to outside to inside on a single span. Tri-ang and Faller made brick/stone viaduct spans that went around R1 curves and didn't look tooo bad. Faller (also Kibri and Vollmer) makes ramp sections of vaguely girder construction intended to sit on graduated piers. Kibri even does a heavy girder bridge which curves about 30 degrees - it is, as I mentioned at the beginning. a physical impossibility.
Greg.P.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

So are most of the curves on model railway layouts.
--
Martin S.

Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Curved arches work. I suspect overly tight ones wouldn't. Both Ribblehead and Glenfinnan viaducts are curved.
http://www.visitcumbria.com/simon/ribblehead-7772.jpg
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Wouldn't it be possible to support the centre of the curved span, to prevent it rolling over?

--
Jane



Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
[ re steel bridge spans ] : > : > Prototypically, a span can't be curved, because the center would be : > outside : > the supporting points at the ends and would roll over. : > The prototype gets over that problem in several different ways that : > I am aware of: : > - very short straight spans. : > - wider straight spans so that the track can curve from inside to : > outside : > to inside on a single span. : : Wouldn't it be possible to support the centre of the curved span, to : prevent it rolling over?
Then there is little to no point in having a curved structure and all the complications, one would just use two (shorter) straight spans - as they do... Duh! :~)
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jane Sullivan wrote:

[...]
[...]
That's what a curved masonry/concrete arch bridge does. John Dennis's Australian example works for this reason, too: the curve is slight, so that the center of moment (as far as I can tell) lies within the footprint of the straight span between the piers. A straight span in its place would be have to be much wider, hence heavier and more expensive.
cheers, wolf k.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Certainly, but then you would effectively have two half length spans :-)
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 27 Nov, 14:12, "Graham Harrison"

You could try :-
Model Railroad Bridges & Trestles: A Guide to Designing and Building Bridges for Your Layout http://www.langtoninfo.co.uk/showitem.aspx?isbn=0890241287
Kalmbach 12452 The Model Railroader's Guide to Bridges, Trestles & Tunnels. http://www.kato-unitrack.co.uk/kalmbach-12452-the-model-railroader-s-guide-to-bridges-trestles-tunnels-20712-0.html
We are talking 'OO' ? If it's 'N' then try Kato N Scale Unitrack http://www.kato-unitrack.co.uk/kato-n-scale-unitrack-745-0.html
This Curved Wood Trestle Kit looks OK but a bit TOO American http://www.walthers.com/exec/productinfo/345-2016
Chris
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

"Bridges for Modellers" is very good and relates everyhting to the prototype. No idea if it covers curved examples.
MBQ
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Graham Harrison" wrote

No kit that I'm aware of, but you might like to take a look at this British example of a curved bridge:-
http://www.flickr.com/photos/blue-diesels/4149173553/sizes/o /
I don't think there's anything uncommon about curved bridges or viaducts, it's just one part of railway infrastructure that is rarely photographed.
One problem with producing a kit of a curved bridge would be deciding on the many variables possible. For starters let's conside
a) method of construction (stone, brick, steel etc)? b) track radius? c) single, double or mult-track?
I guarantee that is a manufacturer produced one, it wouldn't satisfy but a small section of the market.
John.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
John Turner wrote:

A junction on a viaduct! Lovely!
wolf k.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
: John Turner wrote:
<snip> : > : > http://www.flickr.com/photos/blue-diesels/4149173553/sizes/o / : : A junction on a viaduct! Lovely! :
Especially when a collision occurs, Google the Irk Valley Junction accident on 15 Aug 1953 to see what I mean! :~(
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Nov 27, 2:12 pm, "Graham Harrison"

Just seen on the N gauge Yahoo group that there was an article about curved viaduscts in the April 2008 Railway Modeller.
HTH
MBQ
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 20 Dec 2009 10:16:57 -0800 (PST), " snipped-for-privacy@hotmail.com"

Thanks, I will see if I can get a copy. Guy
--
http://www.chapmancentral.co.uk /
The usenet price promise: all opinions offered in newsgroups are guaranteed
  Click to see the full signature.
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.