that arrow in an angle of 45 degrees towards the upright position or alternatively so as to be a direction lying at any angle from a position in which that arrow faces in the opposite direction from that so shown to an angle 45 degrees towards the upright position.
(8) When both arrows shown in the said diagram 3011 are illuminated and extinguished independently of each other the direction of each such arrow may be varied so as to be a direction which lies at any angle between 90 degrees either to the left or to the right of the upright position.
33.—(1) Portable light signals may be used for the control of vehicular traffic in the circumstances specified at (a) to (c) of this paragraph—
(a) on a road where owing to roadworks being in progress thereon or for some other reason, the width of the carriageway of that road is temporarily restricted so that it will carry only one line of traffic.
33.—(1) at a level crossing where a road is crossed by a railway when work in relation to that crossing is being carried out, or
33.—(1) during the progress of temporary schemes of traffic control, if the signals are being operated and maintained by and under the regular supervision of the police or have been erected at a site approved in writing by the highway authority
33.—(2) Such light signals shall comply with the provisions of sub-paragraphs (a). (b),(c},(d),(f) and (g) of paragraph (2) of Regulation 31 or of the said paragraph (2) as varied by Regulation 32.
34.—(1) The significance of the light signals prescribed by Regulation 31(2) or by Regulation 33 shall be as follows:—
(a) except as provided in the next following sub-paragraphs the red signal shall convey the prohibition that vehicular traffic shall not proceed beyond the stop line on the carriageway provided in conjunction with the signals or, if that line is not for the time being visible or there is no stop line, beyond the post or other structure on or in which the primary signals are mounted;
(b) on an occasion when a vehicle is being used for fire brigade, ambulance or police purposes and the observance of the prohibition conveyed by the red signal as provided by the last preceding sub-paragraph would be likely to hinder the use or that vehicle for the purpose for which it is being used on that occasion, then the said sub-paragraph shall not apply to that vehicle; but instead the prohibition conveyed to that vehicle by the red signal shall be that that vehicle shall not proceed beyond the stop line, or as the case may be as provided by the said sub-paragraph, beyond the said post or other structure in such a manner or at such a time—
(i)as is likely to cause danger to a driver of any other vehicle proceeding on or from another road or on or from another part of the same road in accordance with the indications of the light signals operating there in association with the said red signal or as to necessitate the driver of any other such vehicle to change its speed or course in order to avoid an accident, or
