I have a ~32inch span I was planning to bridge the first 150 feet with the nice ME deck plate girder bridge (already built). The last 12 inches are over the approach my yard throat and my reversing loop/mainline (used for continuous running). I am trying to decide between a deck truss (warren) kitbashed Atlas for 12 inches (2 kits required to make 1…) or a warren through truss… any thoughts? I like the look of the deck girder, but since this spans an area where trains could REALLY crash to the cement, I am thinking through truss, and extending a scratch built hand rail and walkway on the plate girder outside. I would love your thoughts regarding this… would it look un-prototypical (I am NOT a rivet counter)? Any of you done this and have pictures? Let me know…
Atlas have a nice new bridge out soon… A big through truss.
I wouldn’t join two trusses end on to make a long one as the depth of the sides would not represent a girder sufficient for the span.
As far as looking reasonably realistic the question you have to answer is “why is one bridge and under girder and the next an over girder”? Come up with a good reason and you have an okay bridge combination. From pics I’ve seen quite a few through trusses in the US are approached by deck girders.
It would help if someone like Mark B. would offer an opinion since he is an engineer, but I have seen pictures with some odd combos, so …take yer pick. Make something up! Make it unique.
Personally, I would use a Warren truss because I have one left over from the previous layout. Aren’t the Atlas ones about 10"?
Thanks, Dave. That is what I am leaning towards…, but just wanted ideas… As for the Altas, it is cool looking… a bit long for me…hmmm need like a 12-15 inch bridge.
Where did you see the new Atlas bridge? Is it to take the place of the 18-inch “Chord Bridge,” which is no longer on the web site? I’ve got one of those, and I think it’s something Atlas needs. All their other bridges are 9-inch.
I use an Atlas chord bridge that I use it mounted on top of my swing up, spanning a 36 door. It has contained a couble of very bad derails over the years. Would be easy to shorten if you wish. Just a thought…John
Yeah the problem I have is I need like 12 inches. By modifying the deck bridge I would just add a panel. The problem with their deck truss bridge is that it is not symetrical, meaning the middle panel is larger than the ends. This is a PAIN if you want to kitbash or make skewed, which was part of my plan [:(]
You probably don’t want a 12"-span truss next to a 20"-span plate girder, unless they can be weathered to represent two widely divergent construction dates (as in the newer plate girder replaced an older truss in the same location). In terms of modern engineering & construction practices, a plate girder is more economical to build and maintain for short and intermediate spans, although trusses remain the way to go for long spans (like crossing major rivers and such). Up through the first half of the 20th century, when steel was expensive and labor was cheap, a truss design was more economical in more cases. So, barring some extenuating circumstance like clearance restrictions, you’re not likely to find many instances of a short truss adjacent a long plate girder on the prototype.
Is the 20" plate girder span one continous span? Or a series of shorter spans supported with piers? Plate girders spans are usually only 30 to 50 feet, although newer ones can approach 70 feet.
For the truss section, have you looked at the Walthers or the Central Valley kits? If they don’t work, the CV bridge girders are a good way to scratchbuild what you need.
That is EXACTLY what I am building (except trains, not water, going under my bridge). The span is 90 feet, so I am thinking a through truss would be more prototypical according to some of the input.
Lead up to the area of question is 5 x 50’ deck girder bridges (ME 150’ kit)… this gets me to the area of question, about 12-15" (90 scale feet) over my yard throat and run-arround, of which 12 need to be a single span (pretty hard to squeeze a support in). What I was wondering, is if a warren through truss bridge or a or warren (or pratt) deck bridge would be more prototypical… I have seen both in prototype (see previous post), just not sure on the spans they would be able to cover without mid support.
I’m thinking that a deck truss bridge would be cheaper (for a real railroad) than a through truss. For one thing, the bridge is narrower–less steel. And when there is that consequent less steel, there’s still less, because you don’t need the bridge to be as strong because there’s less dead weight. I hope that just made sense.
Anyway, I think that’s why deck trusses are generally preferred unlesss there’s a clearance problem underneath. When the bridge passes over waterways, besides the clearance for boats/ships, you’ve also got to deal with flood waters and the consequent trash hitting the lower part of a deck bridge.
I think the above would also apply to girder bridges.
It seems everyone has forgotten this major point. I may be missing something here, but I would build it plate girder leading into a warren truss exiting on plate girder. All supports for the bridges being UP to cover any derailments. Plate girders may be easier to kitbash, so, maybe reversing that to cover that odd length?? I am using a warren truss bridge in a spot just to be certain any trains dont fall off a (straight away) area in the back of the layout. Of course the 9" length is ok for mine.[;)]
Of course, I guess CSX can tell you if a train is going to leave the tracks, then leave the tracks it shall!!![:-^]
Hmmm… great replies guys… thanks for the info! I may do a little of both… a deck girder (warren) with a hefty safety rail (well, brass with piano wire?)… I like that look better. I may modify my area underneath so there is a “safety net” of scenerey below rather than open space…
Why is everyone worried about damage to locomotives from derailments? Derailments anywhere other than at a mis-aligned turnout indicate serious track issues. If you are concerned about tracking on a bridge, slow to yard speed on it, and keep an eye on things. Better yet, do a patient and good job of fixing the bridge into place, and then to laying solid trackwork atop it.
That said, I would also favour the Warren through between two girders…looks prototypical, I think.
So I decided to build the warren truss deck bridge tonight… I combined 2 atlas kits, making the two 3 panel warren deck bridges into one 5 panel deck bridge… here is the frame (unpainted without rail)… I figured I would try since all it cost me is 8 bucks and 3 or so hours of time…
And a close up… I added one support (courtesy of central valley); I also added some old rivet plates cut off an old ?bachman bridge… NOW, I know why I have all that old junk lying around!
In that instance, Mr. B., a tiny bit of plastic ain’t gonna do it. Steel, maybe aluminum, but not a plastic bridge. A rethink in the idea of the span is in order if that type of problem is a serious consideration.
