(1)A toll order authorising the charging of tolls by the highway authority shall in every case specify the maximum tolls which may be charged for the use of the road or any length of the road in respect of which tolls are charged.
(2)The order may specify different maxima for different descriptions of traffic (which need not correspond with the classes of traffic prescribed by the special road scheme) and may provide for the amounts to be varied in accordance with a formula specified in the order.