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.0 INTRODUCTION TO ENGINEERING SURVEY 1.1 Definition of Engineering Survey The term engineering surveying is a general expression for any survey work carried out in connection with the construction of civil engineering and building projects. Surveyors involved in site surveying are responsible for all aspects of dimensional control on such schemes. The main purposes of engineering surveying are * At the concept and design stage to provide large-scale topographical surveys and the other measurements upon which projects are designed. Since this data forms the basis for an entire project, the reliability of the design depends to a great extent on the precision and thoroughness with which the original site survey is carried out. In most cases, the initial survey will be in digital form and computerized equipment will be used to collect and process data. * At the construction stage to provide the precise control from which it is possible to position the works and most importantly, to ensure that engineering projects are built in their correct relative and absolute positions (this is known as setting out). In addition to these, data for the measurement of the works is also collected to enable volumes of material to be estimated during construction proceeds. Engineering survey such as detail survey is usually based on horizontal and vertical control frameworks, which consist of fixed points called control stations. Horizontal control, as its title suggests, defines point on an arbitrary two-dimensional horizontal plane, which covers area of interest. Vertical control, although usually treated separately from horizontal control as far as fieldwork and calculations are concerned, is the third dimension added to the chosen horizontal datum.