This is a great shot, but my initial thought is that the trees in the midground to background and going up the hill almost overwhelm the image and detract from the bridge itself. I thought about maybe cropping it to landscape, but then you'd lose too much. Maybe masking the bridge and river and adding some gaussian blur to the trees to make them fade a little and not provide some dominance...
That's exactly what my wife said, I've burned them in a lot to try and demphasise them, you can imagine how bright they looked originally. Cropping horizontally didn't help for some reason. I think a good part of the problem is that the bridge was stained greeny-brown, there just isn't enough tonal seperation for it to stand out enough, in colour as well as B&W.