A lot of bridges have their pilings set on mini islands, terrifically reinforced piles of stone and concrete that extend for quite some distance around the actual support. I don't know why some are built without that, it always weirds me out seeing the spindly legs going straight into the water, and this is why.

Edit to add: Check out Fort Carroll, precisely such an artificial island just a few hundred yards away in the very same harbor. It was built in the 1840's as a military position to defend the harbor, and has fallen into disuse. Now just imagine if the bridge sat on a couple of those, instead of the foundations it had. Ship would've barely dented the wall.