Macadam is a type of road construction pioneered by an engineer around 1820. Macadam consists basically of compacted layers of small stones cemented into a hard surface by means of stone dust and water . But, the main pavement surfaces in use today are asphalt and concrete coverings.The method of road building uses a layer of well drained and compacted soil to support the load weight of the roadway. While the top layer acts as a wearing surface built only to shed water. (so basically 2 layers)