I have three areas of track that are curved and I need to install bridges in those areas. Who makes bridges/trestles that are curved? How do you match the radius of your track with the radius of the bridge?
Thanks in advance for the help and advice!
Viper
AFAIK there are no manufacturers of curved bridges, so you have a few options:
-Dan
Builder of Bowser steam! Railimages Site
http://www.walthers.com/exec/productinfo/345-2016
Walthers has this one on sale if you want wood.
ME makes steel viaduct bridges that can be built straight or curved. The instructions give you steps to do it either way.
I just bought a curved wooden trestle kit (can't remember the brand and I'm at work now..DOH! ). edit...***! once again lothar beat me to it
There are kits available.
As for the bridge deck curve you would have to make a template that fits the curvature of the particular section of track where it will be. Just build the bridge deck to match your template. You can build the bridge deck with track and then join the bridge track to the existing one or build the deck w/o track and fit it up to the already laid track. Keep in mind though tie spacing on trestle bridges is much tighter than normal spacing on roadbed or earth.
-G-
loathar wrote: http://www.walthers.com/exec/productinfo/345-2016Walthers has this one on sale if you want wood.
Thats a real nice trestle, but the OP never said what scale he's in so that HO scale trestle may not work for him.
With the exception of the newly-developed 'bent box girder' bridge mentioned above, ALL bridges are straight. Even a 'curved' timber trestle has straight under-track stringers, meeting at an angle at each bent.
If you don't want a timber trestle (prototype railroads do their best to avoid them) just use a straight bridge design (single or multiple span) wide enough to allow your track to curve, and make sure that any angles in the bridge structure (where two spans meet) are adequately supported by proper piers. It's easiest to use ballasted-deck bridges, either deck girder or through girder, since laying curved rails on an open deck is a nuisance - and simply putting flex on an open deck doesn't look realistic.
Chuck (modeling Central Japan in September, 1964 - with lots of bridges, some on curves)
Great help everyone. I now know what to do. You all have been wonderful. Now it is off to create my bridges.
This bridge was built in the 1930's... I believe it is a series of straight spans set in an arc, though...
Check Kato Unitrak, I believe they make a curved viaduct system. You're stuck with their radius, though.
Lee
Route of the Alpha Jets www.wmrywesternlines.net
pcarrell wrote: loathar wrote: http://www.walthers.com/exec/productinfo/345-2016Walthers has this one on sale if you want wood.Thats a real nice trestle, but the OP never said what scale he's in so that HO scale trestle may not work for him.
No problem. JV Models makes that bridge in N, HO and O scale. That should about cover it.
loathar wrote: pcarrell wrote: loathar wrote: http://www.walthers.com/exec/productinfo/345-2016Walthers has this one on sale if you want wood.Thats a real nice trestle, but the OP never said what scale he's in so that HO scale trestle may not work for him. No problem. JV Models makes that bridge in N, HO and O scale. That should about cover it.
I thought I recognized it in N scale, but I wasn't sure.
I cut a piece of 3/4" ply subroadbed to fit a curve, added cork roadbed and track. I used Atlas Plate Girder Loads which I cut and glued together and painted black. I then hot glued the completed girders to the sides of the plywood sub roadbed and voila, a curved girder bridge. I will finish off ballasting the track and adding a pier under the middle of the bridge.
Jay
C-415 Build: https://imageshack.com/a/tShC/1
Other builds: https://imageshack.com/my/albums
I have two major curved bridges on the Yuba River Sub--the first is a viaduct on a 36" radius and a descending 2% grade made from two Micro-Scale steel viaduct kits (which comes with instructions on how to adapt the structure to curved track) and the second is a model of a truss bridge that I saw in a photo either on the Chesapeake and Ohio or the Pennsylvania (can't remember which) in which a single track curve was laid in the middle of a double-track truss. I copied that for the particular truss bridge because of clearance problems between upper and lower tracks which would not have allowed either a girder bridge or a tunnel.
Works for me, though.
Tom
Tom View my layout photos! http://s299.photobucket.com/albums/mm310/TWhite-014/Rio%20Grande%20Yuba%20River%20Sub One can NEVER have too many Articulateds!
I was and than k everyone for the ideas. I have what I need to get started. Great Forum. Bless you all!
My layout has a curved bridge, but I made it knowing that I was violating some pretty important engineering principals. Before you make yours you might want to know about them.
The portion of a bridge that actually transmits the weight of a load to the ground is located within the rectangle between the end supports of the span represented by the shaded area in this illustration:
The problem with a curved bridge is when the load goes outside of the rectangle (really trapezoid) - red X. That places a twisting force on the bridge. Building a structure that can withstand the force and stay attached to the supports is a rather difficult thing to do in the real world, so engineers make bridges straight. If a curved bridge is mandatory, it is a series of straight spans, set at angles as in a trestle:
All that said, we model railroaders take numerous liberties with civil engineering and don't sweat it. I think even John Allen had a slightly curved bridge on the G&D. So I say go for it, but if someone ever tells you a span can't be curved, be prepared to admit your use of modeler's license.
Phil, I'm not a rocket scientist; they are my students.
shayfan84325 wrote: All that said, we model railroaders take numerous liberties with civil engineering and don't sweat it.
Speak for yourself, there, Shayfan. I finance my hobby by working days as a structural engineer, and even though virtually every aspect of my layout cries out "UNPROTOTYPICAL!" I could never live with myself if I built a railroad bridge with curved beams!
"I am lapidary but not eristic when I use big words." - William F. Buckley
I haven't been sleeping. I'm afraid I'll dream I'm in a coma and then wake up unconscious. -Stephen Wright
mononguy63 wrote: shayfan84325 wrote: All that said, we model railroaders take numerous liberties with civil engineering and don't sweat it. Speak for yourself, there, Shayfan. I finance my hobby by working days as a structural engineer, and even though virtually every aspect of my layout cries out "UNPROTOTYPICAL!" I could never live with myself if I built a railroad bridge with curved beams!
Sorry. I didn't mean to offend you or anyone else. I meant that as a population thing, not that every model railroader bends the rules of engineering, but that many of us do and we chalk it up to making things work within our limitations. From my experience, most folks don't understand why bridges can't be built with curved spans - in fact, no one has ever commented on it when they see mine (I do use it as an opportunity to educate folks, because you can actually see mine twist when a heavy loco traverses it). My bridge is named Impossible Bridge because of the liberty I took making it curved.
My situation was that I had to choose between a tight radius curve, expanding my layout room, or a curved bridge. It seemed the most reasonable, if not realistic, solution.
We all have standards we won't compromise - I respect you and your standards for structural design integrity.
So, was my explanation accurate?
No offense taken, Phil. I'm just poking a little fun with my own neuroses
You had a very good explanation in layman's terms. I'd love to launch on a long dissertation on torsional stress and restraints, but, to quote R.M. Nixon, "That would be wrong."