Photo taken by Janis Ford Feb 2007
BH Photo #216737
These are what is known as a Bailey truss.
I agree with you, Gene. Take a look at the 50th Street Menomonee River Bridge at http://bridgehunter.com/wi/milwaukee/P40065800000000/ to see a nearly identical structure.
Thats one of those surplus WW2 era. modular bridges.