Curved bridge

Curved arches work. I suspect overly tight ones wouldn't. Both Ribblehead and Glenfinnan viaducts are curved.

OK. Thanks for that.

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

: > 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! :~)

ed

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

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.

Certainly, but then you would effectively have two half length spans :-)

Good ideas, but I am building in brick. Guy

You could try :-

Model Railroad Bridges & Trestles: A Guide to Designing and Building Bridges for Your Layout

Kalmbach 12452 The Model Railroader's Guide to Bridges, Trestles & Tunnels.

Masonry, brick, same technique applies.

MBQ

"Bridges for Modellers" is very good and relates everyhting to the prototype. No idea if it covers curved examples.

MBQ

"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:-

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.

A junction on a viaduct! Lovely!

wolf k.

: >

: >

Especially when a collision occurs, Google the Irk Valley Junction accident on 15 Aug 1953 to see what I mean! :~(

Just seen on the N gauge Yahoo group that there was an article about curved viaduscts in the April 2008 Railway Modeller.

HTH

MBQ

Thanks, I will see if I can get a copy. Guy