Paragraph 6 I1

The triangle must be legibly and permanently marked with the specification number of the British Standard for an Advance Warning Triangle to indicate a temporary obstruction, namely BS AU47: 1965^f1 or the specification number of a corresponding EEA standard.

The surface coloured red and marked A must be reflectorised.

Not more than 15 square centimetre of the surface marked A may be obscured by constructional components.

The surface coloured red and marked B must be fluorescent.

The surface marked C must be either—

Not more than 10 square centimetre of the surface marked A may be obscured by constructional components.

Corners of a triangle must be radiused.

All sides of a triangle must be of the same length.

The reflectorised areas of the surface may be internally illuminated provided that such illumination is steady, presents a uniform appearance throughout that area and does not impair the retroreflecting properties of that area of the surface.

The triangle must not be illuminated through external illumination.