Another thing I forgot to mention- terrorism and emergency situations. It's been said that a bomb going off on the deck of a bridge won't do a whole lot of damage- most of the blast goes up and into the air. That's why trucks are banned from the George Washington Bridge's lower deck, and several NYC bridges now have armour on the lower parts of their suspender ropes, where they are most vulnerable.
About working with the environment- can you imagine San Francisco without the Golden Gate?
I think that in some cases like the shanghai situation, tunnels work better. But for a large crossing like the mouth of Halifax Harbour, I'm still all for the bridge. Just as long as we make it beautiful, however. It seems that here in Halifax, the heritage groups get all up in arms over anything new and different.
I feel that the best suspension bridges are the ones which are not just functional, but also show signs that somebody tried for a little something more than pure functionality. Whether it's the art deco lines of the Golden Gate, or the sleek, graceful modern lines of the Verrazano, looks matter too. I feel that the entrance to our harbour deserves something beautiful, something that we can be proud of.
Look at this:
http://www.bridgemeister.com/pic.php?pid=1403
This bridge was only half the size of the ones we have here in Halifax right now, and in a remote part of El Salvador. But still, she was beautiful. A little gem of a bridge. If we ever do seek to span the Halifax Harbour again, I have but one request of the designers. Learn from little Cuscatlan Bridge's example, and make ours beautiful too. Halifax may not be New York or San Francisco. But surely we deserve a new icon to be proud of.