What Does Macadam Mean?

The word macadam is used as a noun for a kind of the road surface that is made of layers of broken stones. Usually the surface is being made by mixing stones with tar.
     
This kind of surface is usually not used on roads but most of the times you can find its use while making pavements. At few places the surface is used on roads as well but it is becoming extinct and you can find the surface as roads at underdeveloped places only.
    
The surfaces this kind of roads provides are usually not very smooth to ride vehicles and as the purpose of the road itself is to provide smooth ride to vehicles the surface must not be used for roads where vehicles are expected to be driven.