Geotechnical investigation is carried out as feasibility study before road construction with the aim of studying the competence of the subgrade where the road will rest on and for competence of the selected materials for the road construction. The soil mass on which a structure is to be built is heterogeneous in character and no theory can simulate field conditions. Soil deposits in nature exist in an extremely erratic manner producing thereby an infinite variety of possible combinations which would affect the choice and design of foundations (Das, 1994). During the design, the designer has to make use of the properties of soils, the theories pertaining to the design and his own practical experience to adjust to suit field conditions; so as to prevent failure. The properties desired in soils for foundations under roads and airfields are: adequate strength; resistance to frost action (in areas where frost is a factor); acceptable compression and expansion; adequate drainage and good compaction. Some of these properties may be supplied by proper construction methods. For instance, materials having good drainage characteristics are desirable, but if such materials are not available locally, adequate drainage may be obtained by installing a properly designed water-collecting system. Strength requirements for base course materials are high, and only good quality materials are acceptable. However, low strengths in subgrade materials may be compensated for in many cases by increasing the thickness of overlying base materials or using a geotextile. Proper design of road and airfield pavements requires the evaluation of soil properties in more detail than possible by use of the general soils classification system. However, the grouping of soils in the classification system gives an initial indication of their behavior in road and airfield construction, which is useful in site or route selection and borrow source reconnaissance (Casangrade, 1948).