Curved bridge

I assume you want a steel bridge. There's a reason there are no curved steel bridge kits. They don't exist in the prototype.

The only truly curved bridges are masonry or stone viaducts. In the last

30-odd years, curved pre-stressed concrete bridges have been built for motorways and occasionally for railways, but they are still rare.

Curved steel bridges were and are a series of short straight spans set at suitable angles to each other in order to follow the curve. IOW, they're trestles. Very short (50ft (200mm in OO) or less) through bridges are sometimes built wide enough to accommodate curved track.

So if you want prototypically correct curved bridges, you'll have to build viaducts or trestles.

OTOH, Faller makes curved "bridges" for Maerklin C track, radius 36cm (about 14-1/8"). The viaduct version looks OK, the through girder version looks like what it is: a plastic ramp with a few details to suggest it's a bridge.

HTH wolf k.

Well it depends on the type of bridge. Girder bridges cannot be built 'bent' so they go round corners in a series of straight lines. They have to be wider than straight bridges because the track will be curved on the deck. Stone, brick, and concrete bridges can be built curved and there are plenty examples around. I'm afraid you are not going to find any kits, so scratchbuilding is your only course. I have a large curved viaduct (the famous one at Calvine on the old HR, done from the original drawings) on my layout . This was made in 4mm ply with the internal abutments made as solid wood and the deck also 4mm ply, with 1/16" ply on the insides of the arches. The external abutments (fake Scottish castellated towers) were added after assembly and were made by turning them on a wood lathe and sawing them in half. The ply was then covered in Plasticard stonework from Wills with hand laid up stones on the towers. If you would like to see pictures email me at snipped-for-privacy@btinternet.com.

Alistair

Define "bridge", under- or overbridge? Material?

MBQ

Well it depends on the type of bridge. Girder bridges cannot be built 'bent' so they go round corners in a series of straight lines. They have to be wider than straight bridges because the track will be curved on the deck. Stone, brick, and concrete bridges can be built curved and there are plenty examples around. I'm afraid you are not going to find any kits, so scratchbuilding is your only course. I have a large curved viaduct (the famous one at Calvine on the old HR, done from the original drawings) on my layout . This was made in 4mm ply with the internal abutments made as solid wood and the deck also 4mm ply, with 1/16" ply on the insides of the arches. The external abutments (fake Scottish castellated towers) were added after assembly and were made by turning them on a wood lathe and sawing them in half. The ply was then covered in Plasticard stonework from Wills with hand laid up stones on the towers. If you would like to see pictures email me at snipped-for-privacy@btinternet.com.

Alistair

Thank you gentlemen. I think I can see a rethink ahead!

Here's a video showing just such a thing being installed in Melbourne, Australia. But then again what would we know, down in the colonies.... :-)

John

That's a highway bridge.

cheers, wolf k.

There's at least a couple of curved bridges in NZ..

Hapuwhenua (went over this many times as a kid)

Manuherikia But as previously pointed out, they are a series of straight section, arranged in a curve

One the most famous arched Railway bridges in Europe to be constructed on a curve is the Landwasser viaduct in Switzerland. However this shot

shows that this too is actually straight sections set at angles to get the curve. Piers can be built thicker on one side relatively easily but constructing an arch that has further to span on one side than the other is quite a complicated excerise .You are basically constructing a segment of a horizontal cone.

G.Harman

Concrete Bob's viaduct at Glenfinnan on the West Highland line is genuinely curved.

Of course concrete is probably the easiest medium.

Kids will know it from the Harry Potter movies, where the flying car dodged the train.

Nope. It's a triangular connection allowing trains coming from Sydney to head directly to the western line without needing to reverse at Tottenham yard. Here's a recent aerial picture:

John

OK, nice work.

wolf k.

a) the site javascript, and doesn't know how to reload when javascript is enabled; b) the site doesn't take you to the page listed above, but requires some sort of sign, which I didn't bother with.

But I still think the the bridge shown in the video is a nice job. ;-)

wolf k.

Sorry - that site works for me pretty well, although it is new and a bit rought around the edges. For what it's worth, here's a screenshot of the image - reduced in size - showing the curved bridge. Most of the spans are pre-stressed concrete (I think) and are straight, but I guess they couldn't locate the necessary piers for the section over the road, so this is a specially made curved steel span. I read a bunch of information about this just in the last week, but I cannot recall where. If I had read it back in the 60s or 70s I would be able to find it instantly, such is my memory these days....

John

It worked with me when I pressed the "continue" button to indicate I accepted the terms and conditions.

Nope. It's a triangular connection allowing trains coming from Sydney to head directly to the western line without needing to reverse at Tottenham yard. Here's a recent aerial picture:

But, zoom out and you'll see there is a huge triangle with Sunshine at the top left, Footscray at the top right, and Newport at the bottom. What have I missed?

John

This is sound advice but I have a problem with the curved viaduct I am building, it's around 450mm from ground level to parapet and few kits are that tall (plus I want textured effects anyway), so the Plastikard method is looking good. I do, however, have to come up with a way of manufacturing the arches. Suggestions have included plastikard with grooves made using dividers and a knife (for the radial brickwork), and thin flexible ply with a very fine skim of clay, similarly treated. I think the clay is a better bet but can't see how I can do the carving in time to get it done while the clay is still soft enough to curve the ply into place. Guy

Well spotted, but remember, this is Australia here, the land of multiple gauges. The new line is to standard gauge, the existing leg on the western side is broad gauge, and crosses an intensively used double track BG line on the flat. This line carries suburban and regional passenger service, which is not really compatible with having

1800m long freight trains crossing periodically.

John

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.