Thank you for the responses. An apology is in order from me for not being more specific about my plans to incorporate the Bollman Truss design on a curve. I intend to use 3 straight sections of deck truss configuration to span the 30" of distance on my layout. The Bollman, like many truss designs, lends itself to a deck-type as well as a more "built-up" structure with side and overhead support. I have scratch built a 25" deck-type trestle on a 24" radius curve, and it contains 6 straight sections supported by complex cribbed bents, based on a structure I saw in Model Railroader a few years ago. Once I get familiar with importing images from my digital camera to the forum, I'll include it in a future post. I suspected the cost of design software would be too expensive to be justified for this application.
Will.
gandydancer19 There are no single bridges on a curve. All curved bridges are made up of short sections of straight bridges built wider. Then when put together, there is room to curve the track on them.
There are no single bridges on a curve. All curved bridges are made up of short sections of straight bridges built wider. Then when put together, there is room to curve the track on them.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
I would suspect that any program that would be out there that would allow you to design a bridge would either be proprietary, or cost more than you'd want to spend. However, if you Google Bollman Truss you're going to get a lot of information. An example is: http://www.google.com/search?q=bollman+truss+drawings&hl=en&qscrl=1&rlz=1T4GGHP_enUS443US443&tbm=isch&tbo=u&source=univ&sa=X&ei=-KgmUbqGDeiA0AGQ_YDQBA&sqi=2&ved=0CEAQsAQ&biw=1024&bih=654 Another example is: http://mysite.du.edu/~jcalvert/tech/bolltrus.htm.
From the model railroading stand point, if you were to look at the examples, make a guesstimate as to the member sizes, and scratchbuilt a bridge, I suspect that most model railroaders would be awed by such a structure. Any real bridge engineer that happened to come over to your house and started to find fault would just not be invited back.
I would like to scratch build a multiple-span Bollman Truss bridge, on a curve. I would like to hear from any forum members who have used a software program to aid in the design of bridges for model railroads. I am aware of the existence of layout design programs, but suspect that this is a specialized area of design.