Paragraph 9
When the “lower” push-button is pressed, or the train either occupies a track circuit or operates a treadle the sequence of events to close the crossing to road traffic shall begin. The sequence of operation shall be—
the amber lights shall immediately show and the audible warning shall begin. The lights shall show for approximately 3 seconds;
immediately the amber lights are extinguished the intermittent red lights shall show;
4 to 6 seconds later the left hand side barriers on each approach to the crossing shall begin to descend and shall take a further 6 to 10 seconds to reach the lowered position;
the right hand side barriers on each approach to the crossing shall then begin to descend taking 6 to 10 seconds to reach the lowered position;
the audible warning shall stop when all barriers are fully lowered.