(1) In this Act:
"heavy vehicle" means—
(a) a motor vehicle, or trailer, with a GVM greater than 4.5t, and includes—
(i) a special purpose vehicle with a GVM greater than 4.5t, and
(ii) a passenger-carrying vehicle with a GVM greater than 4.5t; and
(b) a motor vehicle prescribed by regulation.
(2) In this section:
"passenger-carrying vehicle" means a vehicle if the primary purpose for which the vehicle was built, or permanently modified, was the carriage of passengers.
"special purpose vehicle"—
(a) means a vehicle if the primary purpose for which the vehicle was built, or permanently modified, was not the carriage of goods or passengers; and
(b) includes a vehicle prescribed by regulation; but
(c) does not include a vehicle exempted by regulation.