How about a floating pontoon bridge that you snap apart when a big ship comes by?
Sounds efficient.
My parents had a place on Sunset Beach, NC for about 20 years. Up until about 7-8 years ago, the only way on and off the island was a one-lane pontoon swing bridge over the Intercoastal waterway. For smaller crafts there were a number of scheduled times of the day it would open and they could come through. For larger commercial crafts they would open it. It made getting on and off the island a pain. Some people actually loved that because it tended to keep the island from getting too crowded.
Of course, it started to become dilapidated and every big storm/hurricane threatened to float it away. So the built a huge concrete bridge now to get on and off the island.
But yeah, pontoon bridges were/are totally a thing.