The term 'road topping' refers to a type of material used to cover roads and other surfaces. The most common type of road topping is TAR, which is a black, sticky substance made from coal, petroleum, or wood TAR. TAR is often mixed with gravel or sand to create a more durable surface. It is also used to seal cracks in asphalt and concrete surfaces. TAR is a popular choice for road topping because it is relatively inexpensive and easy to apply.