Thanks Batman!
Gary
hon30critter Brent: Nice bridge! Dave
Brent:
Nice bridge!
Dave
Thank's Dave. It was in the wee hours of the morning and about thirteen pages in on a Google search that I found an engineering company that specialized in rail bridges. I am sure an engineer would balk at my creation, however, it hasn't collapsed under the massive weight of my 2-10-4 (yet). It looks pretty close to the photo's I found on their website so I am happy.
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
I had a situation where the track had to cross on a hill and a curve with no support available underneath. I spent a long time on websites of bridge engineering companies before I found the solution. The longest unsupported steel girder rail bridge was 172'. This was longer than what I needed to build, so I was lucky there. I then found out that to make the curve work, the bridge would be built wider to accommodate the curved track.
So here is my version of what I found on one of the engineering companies websites.
You could make side by side bridges to handle your double track.
Tnanks ACY
For truly scratchbuilt bridges, you could use any material of sufficient strength. Brass, wood, or styrene are the first that come to mind.
For a kitbashed structure, I would suggest deck girders from Walthers, Micro Engineering, Campbell, or any number of other manufacturers. Components for truss bridges could be obtained from Central Valley. I know of at least one modeler who made a truss bridge from Central Valley components. His prototype did not lend itself to the girder support that was engineered into the Central Valley truss bridge. His prototype had to rely on greater strength in the components, so he built a brass core inside the plastic Central Valley girders. This brass core provided the strength he needed, while retaining the look of open girders. This bridge was pictured in Model Railroad Planning 1997, page 28.
Tom
Where do you guys get the bridge scratch building supplies?
The bridges' decks are always tangential, or straight. They abut another section and deck at an angle on piers built to accommodate the engineering necessary to support the angle deck ends. This is because the girders or trusses that support the decks have to be straight along their major axis. There are, to my knowledge, no curved girders of any length designed to carry hundreds of tons.
While the decks are straight, the ties and rails can follow any path that affords the necessary clearances to the rolling stock from the deck's edge or other structures.
Our host, Model Railroader, recently had a fairly comprehensive article on bridge construction. Large wooden trestles are somewhat rare in the modern age, especially on heavy duty double track mainlines, although I suppose there may be a few in service somewhere. In general, the bridge supporting the track is straight. Some newer lightweight bridges for highway or rapid transit lines use curved girders; but I don't think you'll find any curved girders in use on mainline trackage, at least in North America. If the track is curved, the bridge that supports it will be composed of several relatively short straight segments, with a solid support at the points where those segments join. Most of the time, these will be deck plate girder bridges. Longer ones might be deck truss bridges. A through bridge of any kind could have problems with overhang. However, there are exceptions. The former PRR mainline features a steel double track through truss bridge over the Tuscarawas River at Massillon, Ohio. Those through trusses are unusually wide to allow for the curved track. If memory serves me correctly, I believe there are three spans. To build such a bridge, you would probably have to scratchbuild.
For your location, the most logical would appear to be two parallel steel bridges, with a series of short steel deck plate girder bridges atop steel (or concrete, or stone) towers. Micro Engineering components might be used, or you might consider the recently announced Walthers deck plate girder bridges.
This is the area I want to put the bridge https://www.dropbox.com/s/oxk93vf3n6v2oii/2014-02-07%2008.54.18.jpg?dl=0
Wood tresel about 50 HO ft high.
Scratch built or you may be able to modify a kit. It is going to be wider than a standard bridge.
What type of bridge?
Steve
Im considering installing a double track curved bridge on my layout. The curve is a 28" radius.
What is the best way to proceed? Kit? Scratch build?
All help appreciated