This little span is located north of Pawnee between Pawnee and Ralston. This type of bridge is very unique in that the endposts actually form the abutment or foundation for the bridge.
In the picture below, you can see this more clearly, the endposts extending down under the bridge. This bridge is built with short approach spans. This was a good practice when building this type of bridge. Without approaches, this type of bridge was very prone to failure because the pressure of earth pushing on the posts would cause the lower chord to buckle and fail under load. This type of bridge was popular in the first two decades of the 20th century.