Covering with macadam is a process of paving roads and other surfaces with a mixture of crushed stone, sand, and tar. It is a type of road surfacing that is used to create a hard, durable surface for roads and other areas. Macadam is a cost-effective and long-lasting solution for road surfacing, and it is often used in areas with heavy traffic. The process of covering with macadam involves laying down a layer of crushed stone, followed by a layer of sand, and then a layer of tar. The layers are then compacted together to form a strong, durable surface.