Paragraph 47 Placing of light signals prescribed in regulation 32
Portable light signals may be placed for the control of vehicular traffic only at a site approved by the traffic authority except—
(a)
where the signals are being operated and maintained by and are under the regular supervision of a constable during the progress of a temporary scheme of traffic control;
(b)
on a length of road along which—
(i)
there is no junction carrying vehicular traffic to or from it; and
(ii)
the width of the carriageway is temporarily restricted so as to carry only one line of traffic;
(c)
at a level crossing when work in relation to that crossing is being carried out; or
(d)
on a road adjacent to the temporary site of road, building or engineering works used for the movement of vehicles, materials, plant or equipment within the site of the works.