Bridge options and advice

[James Costello]

Plastruct has some preformed lattice work sections available as well.

[nkalanaga]

I forgot about Plastruct's, probably because I seldom see their parts in my local shops, just tubes and beams.  That would make the job even easier.  With commercial girders it might actually be easier to build ones own than to modify a commercial bridge, and one would know that it fit.

[ryan_wilkerson]

http://www.rslaserkits.com makes some laser cut girder bridge kits using micro plywood and laser board…  they are all single track, but they offer a few different angles.

Thanks Dave, I like those. I will likely need those for another module that will use a pair of them. http://www.rslaserkits.com/N-Details.html

[ryan_wilkerson]

Bob, your bridges looks really good. Thanks for the recommendation and attaching the photos too.
-Ryan

I used the new Atlas bridge kit to kitbash the one of the Lincoln Highway Overpass bridges on my Echo LDE.  I was pleasantly surprised by the excellent detail on the kit and using it was much easier than using Micro Engineering deck bridge parts, which the other bridge (being a different kind of bridge) is kitbashed from.
Photo (1) New Atlas bridge kit used for Lincoln Highway Overpass Bridge nearest camera:
Photo (2) Another view showing how I cut down and relocated the side girders to conform to the prototype's proportions:
Photo (3) Prototype Bridges Side View:
Photo (4) Prototype Bridges Top View:
So, if I were you, and I was going to build the bridges you've shown us, I would definitely use the new Atlas bridge kit as a source of quality parts.
Cheerio!
Bob Gilmore

[ryan_wilkerson]

Thanks OldEastRR for the explanation on how you accomplished the skew while keeping the structural strength. I like the Atlas kit as a start, it's not very expensive and looks close to the prototype with some mods.
I'll get a couple and see how it goes.
-Ryan

There is a very simple, easy way to make a skewed through girder bridge using the Atlas Through Girder sets. (P/Ns #2080/1/2). The kit is designed to snap together (two sides to the deck). So it has 4 slots along the edges of the bridge deck and 4 tabs along the inside lower edge of the girder sides that snap into each other.
If you cut new slots in the ends on one side of the bridge deck, you will be able to position the plate girder in an offset position. You can shift the side one, two or three deck girder sections over from the other side, giving you several angles of skew to choose from.
Once you decide the offset, merely saw new slots in the ends of the deck girders to accept the side in its new configuration. If you are careful and make a rounded end on the slot to match the factory slots (use a small drill bit) you'll be able to snap the kit together as securely as an unmodified kit. In the case of a double-track bridge, you need to modify the deck ends of the other main to match whatever skew configuration you'll need for the whole bridge.
This is a much easier method that kitbashing or scratchbuilding. I know people will think it weird but it does work.

[ryan_wilkerson]

I've noticed that too and hadn't gotten around to asking anyone. Thanks for bring that up Max.
...and thanks Lemosteam for the explanation.

I wonder if someone could make a separate etched metal vertical rib detail that could be placed at whatever spacing is needed for the desired prototype? They are hefty pieces and they stick out quite a bit.
-Ryan

Something struck me looking at that prototype bridge photo.   Notice how the vertical ribs are closer together near
the ends than they are out at the center of the bridge.  Why is that?  I would have thought that the maximum
deflection would occur out at the very center, and that's where you'd want closer-spaced ribs, if anything.
I took a quick gander at some other photos of plate girder bridges.  Some of them share this property, and some do not - having the ribs all spaced equally.

[ryan_wilkerson]

I've always liked your bridge work Mark, very clean builds and look unique.
Thanks for the link to the Interaction Hobbies 64' bridge. I wasn't aware of that one. Any experience with the durability of the "paper" product they use?

I've used both the ME side frames with a scratch built internal bracing and floor (which could easily be skewed by a panel)...
...as well as a laser cut paper product from here...http://www.interactionhobbies.com/N-Scale-64-Foot-Through-Plate-Girder-Bridge_p_12.html
md