Right click on the image, then select “View Image,” to view it full size.
You could use a steel trestle like this one, instead of a wooden one to give you more options.
(http://www.railpictures.net/images/d1/9/9/3/7993.1247616929.jpg)
Rhyman has done something close to what you want to do.
He follow the Rio Grande Southern RR and methods.
His bridge 44B has a span over a creek using a double bent.
You would need to turn that entire double bent 90 degrees to do what you want.
http://www.rhyman.org/articles/new-bridge-44b-at-red-rock-creek
Ophir Colorado bridge 45A used a similar structure to replace a Howe Truss bridge with trestles in 1914-1915. I believe the dimensions of the “cross” timbers was 14 x 30" on 14" trestle timbers instead of the usual 12"
http://www.ghostdepot.com/rg/mainline/san%20juan%20branch/ophir%20loop.htm
RGS bridge standards use 3 on 12 batter on curves and 2 on 12 on straights.
http://www.riograndesouthern.com/RGSTechPages/_bdwhite/rgstec1.htm
Great help everyone. Good stuff, thanks.
Charley
John Le Forestier said:
Well, Jake, I’m not sure that if I were an engineer I would approve of that, but hey, it’s your railroad! The magenta bents, that you have called sub supports, merely sitting on beams, regardless of their size, are a serious problem, and would never get approval, except perhaps in a Bangladesh clothing factory, and then the owner would get arrested…
If it were me, I’d prolly build a couple of stone arches over the lower track to act as bridge supports, and run bridges between them to the tunnel.
Attractive as we may find them, I really don’t think trestle-style structures are the correct thing here. Trestles were most often used over dry gulches, or the dry part of river crossings, and later these locations would be filled in by the railroad with material from a nearby cut until the trestle was partly or completely buried, thus the trestle over time would be converted to fill. There are many large railroad fills in existence today that conceal complete trestles buried within them!
Clearly, completing that kind of earthwork would not be the intention of your railroad in the location described to us here.
I fully agree with you, except the part about wood trestle not being used over flowing rivers. Necessity sometime dictated it be done. The sub-supports can and have actually been used in real life. Here is a picture.
img[img]
This is the Butterfly trestle on the Rio Grande Southern, not to far outside Ophir (I think). The ideal situation is steel supports as they are much stronger and last longer, but wood is a viable option. I was merely trying to design soemthing based off the parameters the OP requested. I used the Butterfly design as a basis for my design.
Again, my design is plausible although not ideal. However, as the OP stated he didnt want to change his track plan.
Jake Smith said:
I fully agree with you, except the part about wood trestle not being used over flowing rivers. Necessity sometime dictated it be done. The sub-supports can and have actually been used in real life. Here is a picture.
img[img]
This is the Butterfly trestle on the Rio Grande Southern, not to far outside Ophir (I think). The ideal situation is steel supports as they are much stronger and last longer, but wood is a viable option. I was merely trying to design soemthing based off the parameters the OP requested. I used the Butterfly design as a basis for my design.
Again, my design is plausible although not ideal. However, as the OP stated he didnt want to change his track plan.
Yea, that’s just south of Ophir, near Trout Lake. It was still standing when I was out there.
The Park Service, has rebuilt and stabilized it, but it is barricaded off to prevent anyone from walking on it.
Fr.Fred