# The Traffic Signs Regulations and General Directions 2016, Paragraph 11

Extent: E+W+S

(1) When the marking is used, studs must also be placed.
(2) The studs must incorporate—
(a) white reflectors;
(b) white retroreflecting material; or
(c) a light source that emits, during the hours of darkness, a steady white light,
or any combination.
(3) The studs must be fitted in opposite pairs within the width of each of the two lines that run longitudinally to the flow of traffic and the studs must be placed not less than 3 metres nor more than 4.5 metres apart.
(4) The external part of the stud that is visible when the stud is in place must be—
(a) white;
(b) of a natural metallic finish;
(c) of another neutral colour; or
(d) 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 white 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 white light.

---
Source: https://www.legislation.gov.uk/uksi/2016/362/schedule/9/part/8/paragraph/11 (the official version)
Page: https://openlegislation.uk/traffic-signs-regulations-and-general-directions-2016/schedule-9/part-8/paragraph-11
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.