(6) The sign shown in diagram 830, 830.1, 830.3, 831 or 832 may be placed on or near a road in connection with a traffic census, if and only if the taking of that census on that road has been approved—
(a) by the traffic authority for the road;
(b) by the chief officer of police of the police area in which the road is situated; and
(c) by or on behalf of the Secretary of State.
(7) The sign shown in diagram 950 may be placed in combination with the plate shown in diagram 950.1—
(a) when the plate is varied to “Cycle event”, only while a cycle rally or similar event is in progress;
(b) in any other case except when the plate is varied to “Cycles crossing”, only while the training or testing of child cyclists is in progress.
Placing of signs varied to show metric units
40.—(1) Where the indication given by the sign shown in diagram 629.1 is varied in accordance with regulation 17 and item 2 of Schedule 16, that sign may be placed only in combination with another sign of the same type whose indication has not been so varied.
(2) Paragraph (1) shall also apply when the sign shown in diagram 629.1 is incorporated as a symbol into another sign.
Mounting and backing of signs
41.—(1) Subject to paragraphs (2) and (3), where a sign (other than a sign referred to in paragraph (4), (5) or in direction 43 or 44) in a diagram in Schedules 1 to 5 and 7, Part II of Schedule 10 or Schedule 12, or a sign of the type prescribed by regulation 53, is mounted on a post or other support specially provided for the purpose (“the post”), that part of the post which extends above ground level shall be of any single colour or in its natural colour.
(2) Where the post is not likely to be readily visible to pedestrians or cyclists, a yellow or white band not less than 140 nor more than 160 millimetres deep may be provided on the post, the lower edge of the band being not less than 1500 nor more than 1700 millimetres above ground level.
(3) Where the support provided for a portable sign comprises several components, instead of complying with paragraphs (1) and (2), the components need not all be of the same colour provided that each is of a single colour or in its natural colour.
(4) Where a beacon or lamp of a kind prescribed by regulation 54 or 55 is mounted on a structure specially provided for the purpose, the structure shall be coloured grey, red, white or yellow, or in alternate bands of red and white or of black and white.
(5) The post provided for the mounting of the sign shown in diagram 7031 shall be coloured in alternate black and yellow bands each 300 millimetres deep with a black band uppermost below the bottom of the sign face, and the yellow bands may be reflectorised.
(6) The sign shown in diagram 7104 or 7105 may be mounted on an object of the size, colour and type of the sign shown in diagram 7101.1.
(7) An identification code for maintenance purposes may be indicated, in characters not exceeding 25 millimetres in height, on the post on which a sign is mounted.
42.—(1) The back of any sign shown in a diagram in Schedules 1 to 5, 7, Part II of Schedule 10 or in Schedule 12, or prescribed by regulation 53, other than the sign shown in diagram 651, 970, 971, 972, 973.2, 973.3, 2610, 2610.1, 2610.2, 7101.1, 7102, 7103, 7104 or 7105 shall be coloured—
(a) black if the sign is mounted on the same post as that on which light signals prescribed by regulation 33(1) (or those signals as varied in accordance with regulation 34) or light signals prescribed by regulation 33(2) and regulation 35 are mounted; or
(b) grey, black or in a non-reflective metallic finish in any other case, except that—
(i) information about sites for placing and the ownership of the sign and an identification code for maintenance purposes may be indicated on the back of
the sign in characters not exceeding 25 millimetres in height, where they are
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