Pin Connection. This is for the main arms of the bridges (there are four). The connection would allow them to rotate. Now that I think about it I may need to design a stop so the bridge doesnt fold up completely.
Cast Steel Shear Connection/Walkway. This connection allows for the walkway to fold up flush with itself which would not have been possible if the metal grate was placed on top of the connections.
Ballast Wheels - This is the device which would attach the ballasts to the arms and allow them to move as the water level rises and falls.