If there is a current running, its speed may increase as it squeezes through the constricted channel under the bridge. At some bridges, a crosscurrent will pull or push boats toward the wooden fenders. Commercial vessels may not be able to stop or maneuver in the narrow ICW channel, so always give them plenty of room at bridges. Bascule bridges are also very common, particularly in Florida. With a bascule a portion of the roadway will hinge straight up into a vertical, or near vertical, position.
Double bascules have two portions of roadway hinged up from opposite sides of the channel.
Sometimes two sets of double bascules will service a divided highway, but all of the bridge portions should open together. However, if the bridge is undergoing repairs one or more sections may not open. These bridges tend to open faster than swing bridges, but still require several minutes. Lift bridges have two towers with the moveable roadway slung between them. The center portion of the bridge lifts vertically until there is enough clearance for your boat.