Cross section of a typical road

When we cut the road from vertically side then we can see the different sections of road. This action is called as cross section of road. We can define easily the different parts of road by cross section. Road structure means the different parts of road which they are made on process just like sub-grade is the lowest part and first step of road that is the natural earth level. 
Second part of road is sub-base course. It is not important part of road. If the sub-grade will be weak then we make sub-base for the strength of road. 
Third part of road is base course that is important part of road and last part of road is surfacing. This is the top part of road. There are some parts of road and its explanation of parts are under here. 

1. Sub-grade
2. Sub-base course
3. Base course
4. Surface course


Sub-grade: Sub-grade is the natural earthen level which on road is constructed. Generally its surface is kept 2 feet high from earthen level. So that the rain cannot stand on road surface. If the road need to make on cutting part so sub-grade will be made under earth surface. Mostly strength of road depends on sub-grade’s durability.

Sub-Base course: This part of road is not important but when sub-grade is weak then we make base for the strength of road by lay stone aggregates or use other suitable materials for providing a new layer that is called sub-base.

Base course: This is the important part of road that bears the load of traffic. All traffics load is converted on this part of road and this part weight mold the on base or on sub-grade. Mostly the strength of road depends on this part of durability. Generally this part of road has been contained on strong aggregate.

Surfacing course: This is the top part of road which that makes equal level of road surface. Similarly the water of road should not be observed on the surface.  This part of road protects the other parts of road. For example, base, sub-base and sub-grade.