(a) When approaching a lift bridge, float operators intending to pass under the bridge can contact the bridge operator via marine band radio 13, or by three distinct blasts or soundings of a horn, whistle, or other signaling device. Such contact or signal must be given at least 1,000 feet from the bridge. Bridge operators will reply with navigation lights, horn or whistle. Green lights indicate that the bridge is raised and ready and the float may advance. Red lights indicate that the float must wait. Where the bridge operator responds by horn or whistle, three distinct blasts indicate the float may advance. Six rapid blasts mean that the float shall come to an immediate stop and await further instructions.

(b) No float operator shall proceed under a movable bridge until the bridge is fully raised and the bridge operator has given the signal to proceed.