SUB-SOIL DRAINAGE AND MOISTURE CONTROL IS NECESSARY TO PROTECT THE ROAD SURFACE.

The hilly areas are affected because of the classification of various types of soils coming in the alignment and the useful life of a road depends upon the type of construction, or road structure, intensity and nature of traffic, bearing capacity of the soil /sub grade, climate conditions and the maintenance. The poor specifications of design and scope may also affect adverse and bring the structure to abnormal position of the carrying capacity for which proper function of traffic loads and the weight of the road way above the base is required to be maintained after taking into consideration the all prone and prospects for the future duty and responsibility to be taken from the type of road construction. Sub soil drainage and the moisture control is too required to protect the road surface and stability. As the moisture content increases the strength of the sub base decreases. This effect of the moisture content is more marked in the case of clayey soils than with the granular soils such as the sand and the gravels. The control of the moisture contents of the sub base of the road structure is an essential feature of the good roads. The main object is to maintain the sub base under uniform condition, as possible by preventing the moisture entering the road bed rather than by drawing all water from it. Road drainage is necessary for removal of water from the road surface as well as from the sub base which must be kept clean and well in grade to function properly. For concrete roads, the drains should not be laid in a herring bone fashion.