Two of the 3 biggest floating bridges in the state of Washington are examples.Hood Canal bridge and Lake Washington bridge. The Evergreen Point bridge (also over Lake Washington) is supposedly the longest floating bridge in the world. It had some incidents but no actual sinkings (either the old or new one). I have driven across the old one when there’s a stiff southern wind. There were waves breaking against the bridge and landing on my car. Scary.
BTW, having a drawbridge in the middle of a floating bridge is a neat engineering trick.
Given the boat traffic and currents, definitely not an option for Italy.
Note that yet another big transit project in the USA currently underway (as of April of this year) is a high speed rail line from Las Vegas to LA.