“Special mobile equipment” shall mean a vehicle not designed for the transportation of persons or property upon a highway and only incidentally driven or moved over a way, including but not limited to ditch-digging apparatus, well-boring apparatus and road construction and maintenance machinery such as asphalt spreaders, bituminous mixers, bucket loaders, tractors other than truck tractors, ditchers, leveling graders, finishing machines, motor graders, road rollers, scarifiers, earth moving carryalls and scrapers, power shovels and drag lines, and self-propelled cranes and earth moving equipment. The term does not include house trailers, dump trucks, truck-mounted transit mixers, cranes or shovels, or other vehicles designed for the transportation of persons or property to which machinery has been attached.