Paragraph 27 B. Conditions and Requirements to be observed by the Operator.
Visual indicators shall be provided at each control point. The indicators shall show when—
(a)
the main power supply is available,
(b)
all the lifting barriers are fully raised,
(c)
all the lifting barriers are fully lowered, and
(d)
at least one of the intermittent red lights of each of the traffic lights on each side of the railway is showing along the carriageway.