38. The significance of the light signals prescribed by regulation 37(1) shall be as follows—
(a)when placed beside the carriageway of a road, they shall convey the prohibition that vehicular traffic on that carriageway (other than vehicles being used in the circumstances described in regulation 36(1)(b)) shall not proceed beyond the signals; and
(b)when displayed on a gantry over the carriageway, they shall convey the prohibition that vehicular traffic (other than vehicles being used in the circumstances described in regulation 36(1)(b)) proceeding in the traffic lane immediately below the signals shall not proceed beyond them in that lane,
and for the purposes of this regulation light signals which are mounted on a post situated beside the carriageway but which are projected over it or part of it shall be treated as light signals placed beside the carriageway of that road.