Like I’ve said, John, you’ve got to get the two bridge leafs to come down very slowly to a complete stop in order to trigger the tongue locks. This is what holds the two leafs of the bridge firmly in place. Otherwise, the bridge leafs will start bouncing, and once they start bouncing, you’ll never stop them from goin’ straight up in the air.
2010, James Newport-Chiakulas, Bridges to Justice: Love, Murder, & Politics in Chicago, iUniverse, page 55