Here is another example: http://bridgehunter.com/ks/marshall/irish-creek/
It is listed as being built in 1940. So far, I think it is the only one of its kind that we have discovered outside of Nebraska. Keep in mind that Marshall Co., KS borders Nebraska, so this may indeed be a very localized design.
I agree that the rivets suggest this. It's a standard I-beam not a built up plate, so it's a pony girder(?) not really a beam.
Unusual but a good design for short, lighhtly loaded spans.
Looking at the side of the girder in Photo 9, it appears this structure is a girder and floor beam structure. With two girders running parallel to the road and numerous floor beams running perpendicular. One can see the rivets in the bottom half of the girders that likely connect to the perpendicular floor beams.
This is an interesting little structure, can say I have seen anything like this out here in the Wild West.
What's it like underneath? Are there the two girders parallel to the road and beams perpendicular, or are there a series of beams, all parallel to the road?
Once again I come across this kind of bridge. I have seen only three, including this one, and all in NE. What gives?
The appearance is different but the structure type the same, with this example in Michigan: http://www.historicbridges.org/bridges/browser/?bridgebrowse...