Page:The Traffic Signs Regulations and General Directions 1975 (UKSI 1975-1536).pdf/24

 (2) The size, colour and type of light signals prescribed by this paragraph shall be as follows:—

(a) three lights shall be used, one red, one amber and one green;

(b) the lamps showing the coloured lights aforesaid shall be arranged vertically, the lamp showing a red light being the uppermost and that showing a green light the lowermost;

(c) each lamp shall be separately illuminated and the effective diameter of the lens thereof shall be not less than 195 nor more than 220 millimetres unless the lens is a lens of the kind shown in diagram 3001 when alternatively the said diameter may be not less than 290 nor more than 310 millimetres;

(d) the height of the centre of the amber lens from the surface of the carriageway in the immediate vicinity shall be in the case of signals placed at the side of the carriageway or on a street refuge not less than 2.4 nor more than 4 metres and in the case of signals placed elsewhere and over the carriageway not less than 6.1 nor more than 9 metres;

(e) the centres of adjacent lenses shall be not less than 305 nor more than 360 millimetres apart;

(f) no lettering shall be used upon the lenses or in connection with a light signal;

(g) the sequence of the signal lights shown for the purpose of controlling vehicular traffic shall be as follows:—

(i) red, (ii) amber and red together,

(iii) green,

(iv) amber.

(3) The size, colour and type of light signals prescribed by this paragraph shall be as follows:—

(a) Four lamps each showing an intermittent red light shall be used.

(b) The lamps shall be so fitted as to enclose a rectangular area bounded by the one pair of sides extending horizontally in relation to the ground and terminating as to each side in the centres of each pair of lenses in these Regulations called "the horizontal pairs") and by the other pair of sides extending vertically in relation to the ground and terminating as to each side in the centres of each pair of lenses in these Regulations called "the vertical pairs").

(c) When the four lamps are erected beside the carriageway, the distance between the centres of the lenses for each of the horizontal pairs shall be not less than 945 nor more than 955 millimetres and for each of the vertical pairs shall be not less than 695 nor more than 705 millimetres in accordance with the arrangement shown in diagram 6032.

(d) When the four lamps are erected over the carriageway, the distance between the said centres for each of the horizontal pairs shall be not less than 1395 nor more than 1405 millimetres and for each of the vertical pairs not less than 545 nor more than 555 millimetres in accordance with the arrangement shown in diagram 6031.

(e) Subject to the provisions of the next following sub-paragraph, each lamp shall be separately illuminated and the effective diameter of the lens thereof shall be not less than 120 nor more than 130 millimetres.

(f) When the signal is operated, each lamp shall show its intermittent red light at a rate of flashing of not less than 60 nor more than 90 flashes per minute, and in such a manner that the lights of one of the vertical pairs are always shown when the lights of the other vertical pair are not shown.