Hong Kong Regulations

ROAD TRAFFIC (TRAFFIC CONTROL) REGULATIONS - REGULATION 15

Occasional traffic signs

Where a traffic sign is placed under these regulations on or near a road for
the purpose of conveying a warning or information from time to time to
vehicular traffic or in connection with a prohibition, restriction or
requirement which relates to such traffic but does not apply at all times, the
sign shall be illuminated by means of internal or external lighting during
such times only as, for the purpose of conveying that warning or information
or in connection with that prohibition, restriction or requirement, it is
necessary that the sign shall be visible from a reasonable distance to drivers
of approaching vehicles.