5.—(1) A local excavation vehicle that is a heavy motor car must not tow any trailer.
(2) But sub-paragraph (1) does not apply to a heavy motor car forming part of an articulated vehicle.
6.—(1) This paragraph applies to a motor vehicle towing a trailer where—
(a)the motor vehicle or trailer is a local excavation vehicle; or
(b)the motor vehicle and trailer together comprise an articulated vehicle that is a local excavation vehicle.
(2) A motor vehicle to which this paragraph applies must not tow any other trailer.