# The Traffic Signs (Temporary Obstructions) Regulations 1997, Paragraph 4


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 shall not be directly illuminated externally.

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Source: https://www.legislation.gov.uk/uksi/1997/3053/schedule/3/part/1/paragraph/4 (the official version)
Page: https://openlegislation.uk/traffic-signs-temporary-obstructions-regulations-1997/schedule-3/part-1/paragraph-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.