# The Traffic Signs Regulations and General Directions 2016, Paragraph 2

Extent: E+W+S

(1) Where the road marking at item 9 is placed in a lay-by, studs may also be placed.
(2) The studs must incorporate—
(a) green reflectors;
(b) green retroreflecting material; or
(c) a light source that emits, during the hours of darkness, a steady green light,
or any combination.
(3) The studs must be placed in the gaps between the broken line that indicates the edge of the lay‑by to drivers of approaching vehicles.
(4) The external part of the stud that is visible when the stud is in place must be—
(a) green
(b) white;
(c) of a natural metallic finish;
(d) of another neutral colour; or
(e) clear,
or any combination (but see sub-paragraph (5) for an exception).
(5) The external part of a stud that is visible when the stud is in place temporarily during road works must be fluorescent green-yellow except to the extent—
(a) it consists of green reflectors or retroreflecting material; or
(b) it is necessary for it to be a different colour or clear in order for the stud to emit green light.

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Source: https://www.legislation.gov.uk/uksi/2016/362/schedule/7/part/3/paragraph/2 (the official version)
Page: https://openlegislation.uk/traffic-signs-regulations-and-general-directions-2016/schedule-7/part-3/paragraph-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.