Need help in building a curved bridge

Can someone give me a idea to bridge a curve with track underneath it. I really don't want to build a tunnel, just want a curved bridge in the area where I have a track floating right now. Please provide some input on this, it would be greatly appreciate it. If there are any curved bridges, other that a Marklin bridge that I could use. I can provide pictures if needed. Once again, any input would be greatly appreciated.

Eric, This question is always tricky. While exceptions are always the rule, for the most part 'bridges' are not curved. Generally if they are metal they are a linkage of straights with wedges on the outer curve. It is difficult to make metal bend and be able to withstand the stresses. Also the basic definition of a bridge is an object suspended between two points. Not easy for a single curved long span. That said, a bridge is a bridge is bridge. Most "curved" bridges were wooden trestles. More modern curved bridges tend to be concrete. You don't see the straight metal sections as they are covered. I personally have never seen a curved metal girder bridge, but they probably exist and have pie-shaped wedges in the outside curve. Hope this helps. Cheers, Jim CCRR:)

Thanks for the information Jim. I might have to enclose it and put a hill or ridge over the area.

Eric, No one said you can't use the Marklin curves. Half the Z scales in the world probably do. Cheers, Jim CCRR:unsure:

The question though is finding them. I can build the supports but, need the decks, if not I am going to Kit bash something.

In Pittsburgh PA, you will find numerous curved railroad bridges. They are are everywhere. One of the more famous ones is the one below. It has approaches from two sides curving in towards the main bridge. But what is interesting is that the curved part of the bridge are actually straight sections cut at an angle to create the elongated curve. This could easily be duplicated on your layout but using short straight bridges and angling their ends to create the curve. Also note, this is a massive double line bridge! You can see the other curved section going off on the left.



The photos is from RailPictures.net"

www.railpictures.net/viewphoto.php?id=306514&nseq=815


Rob

Rob, see: RailPictures.net Photo Usage Policy
I suggest you edit out hotlinked picture and leave just the link ...

Chris

Chris,

Good point in the Railpictures user policy. I do give them credit when I post photos from their pages. I think it is important to keep the images in-situ with conversation, which is why I also give them full credit.

Rob

Hello Jim,
Socalz44 wrote:

Eric, No one said you can't use the Marklin curves. Half the Z scales in the world probably do.

You're right that about half of the Z-world uses the Maerklin curved bridges. I do so too...
...there's just one downside to them: they are only available in 145mm radii. All other radii bridges in Z-scale are either kitbashed or entirely scratch build.

Socalz44 wrote:

More modern curved bridges tend to be concrete. You don't see the straight metal sections as they are covered. I personally have never seen a curved metal girder bridge, but they probably exist and have pie-shaped wedges in the outside curve.

You can find lots of curved metal bridges, but virtually all of them used for highways.

netfiles.uiuc.edu/jfhajjar/www/home/Curved%20Girder%20Bridge.jpg

Modern construction techniques can produce a truly curved deck railroad bridge, but they are extraordinarily rare (indeed, non-existent until this century, AFAIK), and the curve is also extremely gentle. This example is found in Iran:

www.waagner-biro.at/uploads/tx_waagnerbiroreferenzen/RAFSANJAN_IRAN06.JPG

Much more typical truly curved railroad bridges will be stone viaducts, such as this one:

s0.geograph.org.uk/photos/26/13/261327_4d3eb978.jpg

Or, as Jim mentioned, wooden trestles...

www.canadianarchitect.com/common_scripts/xtq_images/212049-104731.jpg

Part of the problem is that, in the model world, curves are radically tighter than they are in the real world, where subtle changes in the angle of straight components create a gentle curve that can fool the eye into thinking everything is curved, as in Rob's example. Here's another, more typical curved deck girder bridge:

aroundtheville.files.wordpress.com/2009/11/curved-section-of-rr-track.jpg

Or this one:

img.photobucket.com/albums/v238/CDF/Rail%20image/52026837_6c22b7fb22.jpg

Camera angles can exaggerate the effect, as in this shot:

pete-n-pam.com/main%20pics/page12pics/carriages%20on%20bridge.jpg

Unfortunately, Märklin's curved bridges could never support anything in real life, not even themselves--they'd simply fall over. Not only are the curves impossibly tight, but the support structure is far too shallow and lightweight. Sorry to disappoint, but it's all to do with physics.

ztrack wrote:

Good point in the Railpictures user policy. I do give them credit when I post photos from their pages. I think it is important to keep the images in-situ with conversation, which is why I also give them full credit.

The issue is not to do with giving them credit; it's to do with hotlinking to photos. I agree that embedding images in posts is better at illustrating a point, but it is after all their bandwidth as well as their photo...

David K. Smith wrote:

Socalz44 wrote:

Much more typical truly curved railroad bridges will be stone viaducts, such as this one:

s0.geograph.org.uk/photos/26/13/261327_4d3eb978.jpg

and here's the probably most famous curved railroad stone viaduct . In Z it would be a radii of 454mm...

And this seems to me the one that makes most out of the curve. The RhB Brusio loop .

ULie wrote:

And this seems to me the one that makes most out of the curve. The RhB Brusio loop .

Yikes! We worry about 4% grades on curves... that's 7%!

zierke.com/shasta_route/picpages/1-3-75.html

ztrack wrote:

Chris,
Good point in the Railpictures user policy. I do give them credit when I post photos from their pages. I think it is important to keep the images in-situ with conversation, which is why I also give them full credit.
Rob

Rob, I agree with you that it is indeed best to insert image into the post for clarity etc, however ...
I don't think you have read Railpictures Photo Usage Policy, so let me quote you precise passages I am referring to:

...All photos ... are Copyrighted © by their original photographers, and may not be reused in any way without express written permission...
Any unauthorized use of these photos, ... non-commercial use...is strictly forbidden...

...we ask that you do not directly link to photos on this website for use on other websites. This is an unnecessary waste of our bandwidth, and costs us money...

So, unless you have permission, or it is your own photo, I am asking you, please, to remove the picture. If you have permission to use it, than put the picture on either ZCS or your own server, to avoid "borrowing" their bandwidth.

Crediting source is sometimes good enough, but not in the case where owner specifically forbids you to use their material.

Chris

bambuko wrote:

ztrack wrote:

...All photos ... are Copyrighted © by their original photographers, and may not be reused in any way without express written permission...
Any unauthorized use of these photos, ... non-commercial use...is strictly forbidden...

Chris,
This subject has always puzzled me a bit, (lack of understanding).

Does the above quote mean you can't download any rail pictures for your own personal viewing for reference later or sharing them with someone else?

Perhaps you could enlarge a bit on the particulars of this issue.
Thanks

Hello Loren,

as I read it you can of course download them for your personal viewing. Even if you want to store them for later use as a reference while building a layout I see no problem. If you want to share them with others it starts to get tricky. If you just view them at home with your wife and kids I still see no problem, but when you want to publish them in any way: in a thread like this, or as a background on your layout that you show on an event, or in a book that you are writing about making trees (hey couldn't you do that... ) or in a magazine online or printed you need the permission of the owner of the rights on this picture. This permission you have either to get from the owner directly: written permission, or maybe it is given in advance like for some pictures at wikipedia.

Ulie, got it right as far as I am concerned.
Anyway... let's not hijack curved bridge thread
If we want to discuss copyright, netiquette, etc, etc - start another thread please

Chris

Thanks Chris and Uwe,

That's kind of what I figured, but wasn't real sure.

Back to curved bridges.......

All really good points. Was running on the area today to try and figure something out. Right now I am using a piece of incline and I think I can get 2 small bridges in the area. Still working on it. Having a little problem running long trains there due to the curve and incline. That's another problem that I'll be working on or otherwise run shorter trains. It is a learning experience that I am enjoying throughly, once again, thank you everybody for your input.