9.—(1) The overall height of a bus shall not exceed 4.57 m.
(2) Save as provided in paragraph (3), no person shall use or cause or permit to be used on a road any semi-trailer if—
(a)any part of the structure of the vehicle is more than 4.2 m from the ground when the vehicle is on level ground; and
(b)the total laden weight of the semi-trailer and the vehicle by which it is drawn exceeds 32,520 kg.
(3) For the purpose of paragraph (2) the structure of a vehicle includes any detachable structure attached to the vehicle for the purpose of containing any load, but does not include any load which is not a detachable structure or any sheeting or other readily flexible means of covering or securing a load.
The provisions of paragraph (2) do not apply in respect of any vehicle while it is being loaded or unloaded.