Heavy construction machinery, including but not limited to land movers, bulldozers, front-end loaders, graders, packers, power shovels, cranes, pile drivers, forest harvesting and silvicultural activity equipment and ditch and other types of diggers owned by businesses other than those set forth in §§ 58.1-3507, 58.1-3508, and 58.1-3508.1 shall constitute a classification for local taxation separate from other classifications of tangible property. The rate of tax imposed by a county, city, or town on such machinery and tools shall not exceed the rate imposed upon the general class of tangible personal property.