Awesome bridge Graham!! I love the look of it in #2. If it were mine, I'd crop the entire left side off, just to the left of the green truck, making it a vertical shot... with those wonderful road lines and then the curve of the bridge, it's really a very cool shot!
I love the cropped version (#4)! But what matters is if you do? For me it's as I expected it would be, with the lines of the photo, both road and bridge really dominating the shot. Now it almost looks like a gigantic caterpillar crawling toward the highway! 8^)