4. The back of any crossing sign shown in a diagram in Schedule 1 and any post or other structure specially provided for mounting the sign shall be coloured black or grey.
5.—(1) Any variation in a dimension specified in Schedule 1 shall be treated as permitted by these Regulations if the variation is not more than 5% more or less than the dimension specified.
(2) In the diagrams in Schedule 1 the dimensions given are expressed in millimetres.
6.—(1) Where the circumstances so require the indication given by a crossing sign shown in a diagram in Schedule 1 may be varied in the respect (if any) shown below the diagram relating to that sign.
(2) Where a crossing sign in a diagram in Schedule 1 contains an indication as to the penalty relating to a failure to obey the requirements on that sign, the indication of the penalty may be varied when necessary to accord with changes in the legislation governing the nature and level of penalty.
7.—(1) Subject to paragraphs (2) and (3) of this regulation all parts other than the back of every crossing sign shown in a diagram in Schedule 1 shall be illuminated by means of retro reflecting material.
(2) No retro reflecting material shall be applied to—
(a)any part of a crossing sign coloured black; or
(b)the red and green lights in the crossing signs shown in diagrams 107 and 108 and prescribed in regulation 8.
(3) Retro reflecting material need not be applied to a crossing sign at a crossing that is not used by motor vehicles.
8.—(1) The crossing signs shown in diagrams 107 and 108 shall contain red and green lamps which are internally illuminated by a steady light in such a manner that—
(a)when one light is illuminated the other is not illuminated;
(b)the green lamp is and remains illuminated for so long as no railway vehicle is approaching the vicinity of the crossing from either direction; and
(c)the red lamp is and remains illuminated for so long as the green lamp is not illuminated.
(2) The lenses of the lamps shall be—
(a)circular and not less than 60 millimetres in diameter; or
(b)rectangular with each side measuring not less than 60 millimetres; and the distance between the edges of the lenses of the green lamp and the red lamp shall be not less than 40 millimetres.
(3) The information, warnings, requirements and prohibitions conveyed by the lamps described in paragraphs (1) and (2) shall be as follows—
(a)the red lamp when illuminated shall convey the warning that a railway vehicle is approaching the vicinity of the crossing and the prohibition that persons must not proceed across the crossing;
(b)the green lamp when illuminated shall convey the information that no railway vehicle is approaching the vicinity of the crossing and persons may proceed across the crossing;
(c)if neither the red nor green lamp is illuminated persons should either telephone the crossing operator or proceed across the crossing with caution after having ascertained that no railway vehicle approaching the vicinity of the crossing in accordance with the instructions shown on the sign.