17Classification of traffic for purposes of special roads
(1)Different classes of traffic may be prescribed by a scheme under section 16 above in relation to different parts of the special road to which the scheme relates.
(2)The classes of traffic prescribed by any such scheme shall be prescribed by reference to the classes set out in Schedule 4 to this Act.
(3)The Minister of Transport may by order amend the said Schedule 4 by varying the composition of any class of traffic specified therein or adding a further class of traffic to those so specified, and references in schemes under the said section 16 made (whether by the Minister of Transport or a local highway authority) before the date on which the order comes into operation to any class of traffic to which the order relates are to be construed as references to that class as varied by the order or, if the order so provides, as including references to an additional class created thereby, as the case may be.