2. A special road train operating permit may be issued to authorize the operation of the following road trains on the condition that they meet the characteristics specified in sections 3 and 3.1:(1) an A train double: a road train composed of a tractor, a semi-trailer and a tandem-axle single drawbar dolly that converts the second semi-trailer into a trailer;
(2) a B train double: a road train composed of a tractor, a semi-trailer and a second semi-trailer resting on a fifth wheel mounted at the rear of the first semi-trailer;
(3) a C train double: a road train composed of a tractor, a semi-trailer and a tandem-axle double drawbar dolly that converts the second semi-trailer into a trailer; and
(4) a train double: a road train composed of a tractor, a semi-trailer and a tandem-axle dolly.