# The Traffic Signs (Temporary Obstructions) Regulations 1997, Paragraph 1


The areas marked A B and C in the diagram indicate areas of the surface on the face of the triangle as follows:
A—Red reflectorised surface.
B—Red fluorescent surface (having an area of not less than 315 square centimetres).
C—Red edging which may be omitted.

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Source: https://www.legislation.gov.uk/uksi/1997/3053/schedule/3/part/2/paragraph/1 (the official version)
Page: https://openlegislation.uk/traffic-signs-temporary-obstructions-regulations-1997/schedule-3/part-2/paragraph-1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.