Hello everyone:
The club is contemplating adding a curved double track bridge across a fairly wide river valley. The bridge will be approx. 40" long with a 39.5 degree radius. I would like to do it in three sections if possible (i.e. two supports plus the abutments) but that is not essential. I recognize that this will not be a simple kit build. I am prepared to do some kitbashing and/or scratch building as necessary, but if I can simply modify existing components that would be my preferred choice.
Any suggestions as to how to do this and what components to use?
Thanks,
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Two short spans connected at an angle. They don't make bridges, at least for railroads (that I have seen yet) with curved deck stringers.
You'll have to make the decks wide enough to accommodate the sweep along the curve of locomotive pilots, cab roof extensions, cyclinder covers, the middles of long passenger or other cars, etc.
You could do what a friend of mine did.
He is a CNC Machinist, and his w*^kplace needed to test a new program out. As the tester, he drew in the computer and milled a 18" double track Warren Truss bridge. (They needed to see if the new program could do smaller sized milling, and a HO scale bridge contained enough small parts to fit the bill.) He did the bottom as one piece, then each side as another.
Each side had a milled in slot that mated perfectly with the bottom piece, making assembly quick and easy.
Weathering would be a breeze, just get it in some damp environment for a little while and it will naturally begin to rust! (He painted it with red auto primer.)
The plus side, was, they got the test results they were looking for, (It easily passed the needed specs) and he got a double track bridge (minus scale sized rivets, but no big deal there), and got paid to do it!
So, you could have a scale sized ("operator" style, as ScaleTrains puts it) steel railroad bridge, made out of actual steel!
But as most of us don't have access to a full CNC machine, (although maybe a possibility? Some shops will "contract out" smaller sized jobs, just like this, during slow times. I know for a fact my friends shop does just that. He said if I ever wanted one, do it either mid-spring or right around holiday time, as that is this shops slowest time. Might be worth checking into.) I would go for some ME or CV components and kitbash it.
Ricky W.
HO scale Proto-freelancer.
My Railroad rules:
1: It's my railroad, my rules.
2: It's for having fun and enjoyment.
3: Any objections, consult above rules.
selectorTwo short spans connected at an angle.
Hi selector:
I already had that part figured out, at least in theory anyhow, but how do you mitre two truss bridges so that they join at an angle? Cutting the ends of the truss bridges at an angle doesn't seem realistic to me. I think it would compromise the structural integrity in the real world, or am I wrong. Would it be realistic to build one side of a truss bridge shorter than the other? That would cause the cross framing to all be at different angles. That doesn't seem realistic to me either.
It would be easier to mitre deck girder bridges, and that is what we plan to do for several of our single track bridges, but how do I build a double track deck girder bridge? Is this a scratchbuild or is it realistic to put two deck girder bridges side by side?
hon30critter...Would it be realistic to build one side of a truss bridge shorter than the other? That would cause the cross framing to all be at different angles. That doesn't seem realistic to me either....
Skewed truss bridges aren't all that uncommon, and their cross bracing may also be skewed. If it has to be a truss-type bridge, I'd do it as a deck bridge, which could alleviate some of the clearance problems mentioned by selector.Building it as three spans means that the bridge has to be fairly wide to accommodate the curve, though.This one, over 20 Mile Creek (difficult to photograph from this close, but you can see the whole thing from the QEW at Jordan (if you have the nerve to stop on that highway) was a double track deck truss, single-tracked when CN installed CTC on this line (the girder is atop one of the support towers)...
However, it's not curved...
I'd guess that three deck spans using girders could work, too (it would allow you to not worry too much about the arrangement of the interior bracing, unless visible from below), but girders would need to be fairly deep, I think, to accommodate the width needed for the curve. My tendency would be to make perhaps four shorter spans, whether they were deck trusses or deck girders, as I think that it might look more prototypical and more interesting to the viewer.However, my first choice would be for a concrete arch, perhaps not as elaborate as this one...
...but you could make almost the entire construction from a single 4'x8' sheet of .060" sheet styrene (with plenty left over for other jobs). With a ballasted deck, no worries at all about bracing, or angled cuts, either.
Wayne
doctorwayne However, my first choice would be for a concrete arch, perhaps not as elaborate as this one...
Hmmm...
Thanks Wayne
hon30critter doctorwayne However, my first choice would be for a concrete arch, perhaps not as elaborate as this one... Hmmm... Thanks Wayne Dave
https://www.american-rails.com/thomas-viaduct.html
Thomas Viaduct has been in continuous service since 1835. Can you imagine an engineer explaining why the B&O needed a 26 foot-wide bridge back then, which still carries double track today! Not only is it curved but it is built on a slight grade.
https://en.wikipedia.org/wiki/Thomas_Viaduct
Count me in on the stone or concrete arch. Another of my favorites is Rockville bridge on the old PRR main line.
Regards, Ed
"One difference between pessimists and optimists is that while pessimists are more often right, optimists have far more fun."
https://www.american-rails.com/thomas-viaduct.html Thomas Viaduct has been in continuous service since 1835. Can you imagine an engineer explaining why the B&O needed a 26 foot-wide bridge back then, which still carries double track today! Not only is it curved but it is built on a slight grade. https://en.wikipedia.org/wiki/Thomas_Viaduct Count me in on the stone or concrete arch. Another of my favorites is Rockville bridge on the old PRR main line. Regards, Ed
Thanks for that reference to Thomas viaduct. I have plans to use some of that bridge sencery on my new layout
http://cs.trains.com/mrr/f/11/t/265819.aspx?page=4#3083645
Brian
My Layout Plan
Interesting new Plan Consideration
Doctor Wayne has answered you most capably, as is always the case.
You might try a cut-off disk, a larger one with the air holes to help with angles. A truss of any model quality will be a bit of work, but if you tackle it patiently, and in several short sessions, you could do it. Otherwise, a through or deck girder might be a better solution. No matter what, a girder would almost certainly not be for a double-wide deck, not for the weights involved in the bridge structure itself and not for the loads.
I have seen through girders doubled up with their inner girders up close to one another, but never mutually supporting in any way. If one of the twin spans fails...................
Here is a very good example of an angled deck girder. Photo is mine, taken at Lytton, British Columbia, Canada, where the Thompson and Fraser Rivers meet.
This is the same place, taken some few years earlier when a wreck required extensive rebuilding of the bridge. It shows the angles better. The heavy girder in orange at the top of this photo is part of a road bridge. I was standing under it on both occasions, but worked harder at squatting for the older varnish photo.
selector The heavy girder in orange at the top of this photo is part of a road bridge. I was standing under it on both occasions, but worked harder at squatting for the older varnish photo.
The heavy girder in orange at the top of this photo is part of a road bridge. I was standing under it on both occasions, but worked harder at squatting for the older varnish photo.
Very commendable. It's important to set priorities.
Robert
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