By the Middle Fork of the Powder River looking south-south-easterly at the Barnum Rd. (Johnson Co. Rd. 78) bridge. Kaycee, WY
Photo taken by Panoramio User elifino57
License: Creative Commons Attribution-NonCommercial-ShareAlike (CC BY-NC-SA)
View this photo at panoramio.com
BH Photo #266709
Actually, it kind of looks like they slapped those trusses on the side of a stringer bridge. And the deck surface sits kind of high in the trusses. It looks rather strange.
I've got a guess what they did in 1989/1990, but no clue why.
Both bridges just look wrong in streetview.
NBI gives a 1990 date for this bridge. Obviously, this is a historic bridge, so perhaps the bridge was moved here in 1990?
This link shows the bridge photo Dave found in full size
http://static.panoramio.com/photos/original/68647689.jpg
I think I see floor beams under there, suggesting the truss still functions. However, the unusual appearance may be because the deck stringers rest on top of the floor beams. Sometimes deck stringers were originally riveted to the web of floor beams, which would lower the roadway, and make the truss look normal. Not sure if this bridge was originally like that, its all speculation with only one photo to go on.