9. When the train either occupies a track circuit or operates a treadle the audible warning devices and the traffic light signals shall begin to operate and the barriers shall be lowered in accordance with the following sequence—
(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 shall begin to show;
(c)4 to 8 seconds later, the barriers shall begin to descend and shall take a further 6 to 8 seconds to reach the lowered position;
(d)not less than 27 seconds shall elapse between the time when the amber lights first show and the time when the train reaches the crossing;
(e)the intermittent red lights shall continue to show and the audible warning device shall continue to sound until the barriers have begun to rise and all said lights and devices shall be switched off before the barriers have risen to an angle of 45 degrees above the horizontal. However, if the barriers have not fully risen within 7.5 seconds of having started to rise then the red road lights will be illuminated until both barriers are proved fully up.