Paragraph 43
When a train either occupies a track circuit or operates a treadle the sequence of events to close the crossing to road traffic shall automatically begin. The sequence shall be:–
(a)
the amber lights shall show and the audible warning shall begin. The lights shall show for approximately 3 seconds;
(b)
immediately the amber lights are extinguished the intermittent red lights of the traffic light signals and the pedestrian warning lamps shall show;
(c)
4 to 6 seconds later the barriers shall begin to descend and shall take a further 6 to 10 seconds to reach the lowered position.