I've visited this bridge, it functions as a truss. Photo #16 shows the transverse floorbeams which indicate that the trusses are indeed functioning to handle live loads. The longitudinal deck stringers bear on the floorbeams.
Are the trusses on this even load-bearing? The "floorbeam" system on this looks more like load-bearing stringers to me.
Okay, I see now. Sorry, I scrolled through too fast and thought the pictures of the approaches were main spans.