20Definition of “heavy commercial vehicle” for the purposes of section 19
(1)In section 19 of this Act, “heavy commercial vehicle” means any goods vehicle which has an operating weight exceeding 7.5 tonnes.
(2)The operating weight of a goods vehicle for the purposes of this section is—
(a)in the case of a motor vehicle not drawing a trailer or in the case of a trailer, its maximum laden weight,
(b)in the case of an articulated vehicle, its maximum laden weight (if it has one) and otherwise the aggregate maximum laden weight of all the individual vehicles forming part of that articulated vehicle, and
(c)in the case of a motor vehicle (other than an articulated vehicle) drawing one or more trailers, the aggregate maximum laden weight of the motor vehicle and the trailer or trailers attached to it.
(3)In this section “articulated vehicle” means a motor vehicle with a trailer so attached to it as to be partially superimposed upon it; and references to the maximum laden weight of a vehicle are references to the total laden weight which must not be exceeded in the case of that vehicle if it is to be used in Great Britain without contravening any regulations for the time being in force under section 41 of this Act.
(4)In this section, and in the definition of “goods vehicle” in section 192 of this Act as it applies for the purposes of this section, “trailer” means any vehicle other than a motor vehicle.
(5)The Secretary of State may by regulations amend subsections (1) and (2) above (whether as originally enacted or as previously amended under this subsection)—
(a)by substituting weights of a different description for any of the weights there mentioned, or
(b)in the case of subsection (1) above, by substituting a weight of a different description or amount, or a weight different both in description and amount, for the weight there mentioned.
(6)Different regulations may be made under subsection (5) above as respects different classes of vehicles or as respects the same class of vehicles in different circumstances and as respects different times of the day or night and as respects different localities.
(7)Regulations under subsection (5) above shall not so amend subsection (1) above that there is any case in which a goods vehicle whose operating weight (ascertained in accordance with subsection (2) above as originally enacted) does not exceed 7.5 tonnes is a heavy commercial vehicle for any of the purposes of section 19 of this Act.