The Old Swing Bridge
The canal builders knew they had to build a bridge for traffic to cross the canal.
Their solution was to make a bridge that rotate the spans out of the way for the boat traffic.
So the cars and trucks would have to wait while boats went through the locks.
There is a matching rotating span on the other side of the locks, and when they
rotated to let the traffic across, the spans would meet in the middle.
The Bridge Of The Americas replaced this bridge which is no longer used.