railroad bridge. curved. suggestions?


tankist

tankist

Active Member
at the moment my 2 bridges are just plywood planks with track glued (reliable operation was my primary consern). i have several ideas how to make those bit more realistic. however i'm for your ideas and input as well.

not sure exactly what i was going for, i guess i was under impression of old RR bridge in St' Paul , MN, i visited but both bridges are "see through" - i made a cutout in the middle of plywood plank. that can be closed if so needed. i was thinking canibalaising some C83 flex or even C55 N scale flex track to create guard rail in the middle for both.


short bridge.
that one i guess i could "straighten" out. from what i see prototype bridge for curved track is usually straight but wider to accommodate the curve. then either add shallow truss from below or above. or make it into "tub bridge": add two sides, close from the bottom and fill with ballast...

DSC89591-vi.jpg



long bridge
that one the only idea i have is to call it a concrete box girder bridge. shave and paint the ties gray concrete. clearance from below is critical so o wouldn't extend it down more then few milimeters (for the girder)

DSC_8957vi-vi.jpg





your input is welcome
 
If the small one isn't that long, then you could get some plate girders from Atlas and glue/attach them to the deck to make a curved plate girder bridge. Atlas Flat Car girder load from MB Klein are 7" long and I've got some spares that I can send you, no charge.

I don't know what to do with the second one, other than a trestle. I had thought about using a double-track truss bridge (minus the double track), but whatever you do, it will be custom.
 
The short bridge can be done easily with some plate girders, You just need to widen to the cleances a bit on the sides to the trains don't strike the bridge.

The longer one (how long is it? I can't tell from the picture) would be ideal for a wood trestle, except for the fact the upper track seems to follow the curve of the lower track almost exactly, which means there's no place to put the trestle bents. The only other alternative is a through truss bridge. Is there some way you can straighten the cuve on the long section? If so, the Central Valley 150' through truss bridge would be ideal, assuming you have anough side clearance and the rock faces.
 
realize that on plate girder bridges, the plates are always straight between supports, so that's why the suggestion to make them wider than normal to accomodate the curved tracks.
 
thank you guys. now i realize that instead of the long bridge what i should have done is probably a tunnel... i will look into trestles bu i don't think there is room for supports.

Trey, thank you for the offer. if you have a pair of these idling i will gladly take them to try. PMing you my address and let me know your PP to send shipping charge
 
What era will this be?

Just a few miles from where I live, they widened US 23 into four lanes and one section goes over a RR track. They used what looks like a large steel culvert that the track runs through and the highway crosses the valley on a large fill. For the long bridge, you could put the lower track through something like that and create a fill to carry the upper track.

For an earlier era you could make it look like cut stone or poured concrete.

For the short one, just space the bridge sides far enough apart to let the trains through.
 
Alco has a pretty good idea. I'd make a square culvert out of 1/2" styrene, run the bottom track through that, and then backfill over it and run the top track across the top of the fill. This is what the SP did when they had to cross the UP/ASTF track on Cajon Pass when they were bulding the Palmdale Cutoff.
 
A short tunnel for the lower track would look pretty cool, (just for where the longer curve goes overhead), and having the short bridge there would look cool too.
 
yep, i really really like the idea of tunnel/culvert covered with fill. its going to hurt removing already shaped rocks but at the end of it this solution seems most realistic.
thank you guys.
 
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Do you have to remove the molded rocks? I'd think you'd just need to attach a roof that the long curve can sit on.

The plate girders are en route. I sent 4, in case you want to splice two of them together to make them longer or have another bridge opportunity.
 
If it's not to late. This is a concrete bridge I scratch built. It was designed with the NH concrete bridge at Woodlawn, NY in mind. Maybe you could do the same thing except have the side support walls smaller.

NYC_George
 
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