The laboratory tests that will be described throughout this manual provide information useful in the identification and characterization of soil samples and their engineering behavior. However, any laboratory investigation must start with the collection and evaluation of

in situ

soil properties. In the field, engineers gather information about the topography, surface

hydrology, vegetation, and the general geology of the proposed construction site. This information is complemented with a number of drilling and

in situ

testing techniques (e.g., cone penetration, vane shear, dilatometer, geophysical testing, etc.) that permit the collection of disturbed and undisturbed soil specimens and the characterization of the behavior and properties of soil formations. The collected information helps geotechnical engineers generate a complete site plan for a successful construction project. By combining site and laboratory investigations, the project engineer develops five phases of the geotechnical investigation: preliminary studies, field subsurface investigations, laboratory testing, reporting, and recommendations.