be not less than 595 nor more than 705 millimetres and for each of the vertical pairs shall be not less than 945 nor more than 955 millimetres;
(e) when the four lamps are erected over the carriageway, the distance between the said centres for each or the horizontal pairs shall be not less than 1045 nor more than 1055 millimetres and for each of the vertical pairs not less than 545 nor more than 555 millimetres;
(f) when the sign is operated, each lamp shall show the said light at a rate or flashing of not less than on nor more than 90 flashes per minute, and in such a manner that the lights or one of the horizontal pairs are always shown when the lights or the other horizontal pair are not shown;
(g) the height or the centres of the lenses comprising the lower of the horizontal pairs from the surface or the carriageway in the immediate vicinity shall be in the case of signs placed beside the carriageway not less than 1.8 nor more than 3.2 metres and in the case of signs placed over the carriageway not less than 5.5 nor more than 6.8 metres;
(h) no lettering of any kind shall be used upon any of the lenses.
(4) The light signals prescribed by paragraph (3) shall convey to traffic the warning that the display of a large sign shown in a diagram in Part I of Schedule 6 is due to the existence of temporary hazardous conditions on or near the motorway.
(5) where the circumstances so require, the indications given by the signs shown in Part I of Schedule 6 may be varied as in this paragraph provided, that is to say—
(a) any indication given by such a sign may he varied in the respect (if any) in which it is shown below the diagram relating to that sign that the indication may be varied;
(b) in the sign shown in diagram 6001, the numerals may be varied to accord with the circumstances.
40.—(1) Subject to the provisions of these Regulations, a lamp showing either a steady or an intermittent light may be used to indicate to traffic the limits of a temporary obstruction of a road and shall be or the size,colour and type prescribed by paragraph 2.
(2) (a) The colour of the light shown by the said lamp whether steady or intermittent shall be amber.
(b) Each lens or the lamp shall be—
(i)if the light so shown is emitted from the lamp in only one, two or three horizontal directions, of such a shape and size that the perimeter of its horizontally projected area on to any vertical plane shall be capable of lying wholly inside a circle having a diameter of 150 millimetres and wholly outside a circle having a diameter or 100 millimetres, and
(ii)if the light so shown is emitted from the lamp in every horizontal direction, of such a shape and size that the perimeter of its horizontally projected area on to any vertical plane shall be capable or lying wholly within a square having sides or 125 millimetres in length and wholly outside a square having sides of 40 millimetres in length.
(2) Each such lamp shall be illuminated separately and by a single source of light.
