Construction

Since a major portion of the goods manufactured in a country are transported on roads, construction of an efficient road network plays an important part in the economy of the country. Poorly maintained roads result in loss of manhours as well as wastage of fuel due to frequent vehicle breakdowns and traffic jams. Economic factors play an important role in determining road routes, though political considerations are also important in many countries.

For construction of a road, many legal, environmental, planning and design factors have to be considered. After the necessary approval has been obtained, a surveyor decides the actual alignment of the road. The area is first excavated, filling material is added and compacted. The filling material usually consists of gravel or broken rock below a particular size and should be free of clay. After each layer of filling, the road should be proof rolled. 

The material of the filling also depends on the vehicles which will use the road. If the road is an interstate highway on which container trailers and other heavy vehicles ply, the load bearing capacity should be higher.